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Biodefense Reference Library
Foreign Animal and Zoonotic Disease Center
One Medicine: One Health (Zoonotic Disease)
Online Course
Presented
by
Stephen M. Apatow,
Director of Research and Development
Humanitarian Resource
Institute Biodefense Reference Library
Foreign Animal and Zoonotic Disease Center
[Vitae][Email]
ZOONOTIC DISEASES
VIRAL
CONTAGIOUS ECTHYMA
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Orf, Contagious pustular dermatitis, Contagious Pustular Stomatitis,
Ecthyma Contagiosum)
AGENT:
Genus Parapoxvirus of Family Poxviridae.
RESERVOIR
AND INCIDENCE
Sheep and goats worldwide.
TRANSMISSION:
Crusted areas on muzzle, eyelids, oral cavity, feet, or external
genitalia are laden with virus. Transmitted easily from animals to man by
contact. The virus is highly resistant to adverse environments and persists
for many years.
DISEASE
IN ANIMALS:
Necrosis in the skin and mucous membranes of the gastrointestinal
and urogenital tracts. Intense pain can interfere with eating.
DISEASE
IN MAN:
Large painful nodules usually distributed on the hands. Weeping
red surfaces. These resolve with minimum scarring 1-2 months later.
DIAGNOSIS:
Diagnosis is made by a history of contact with sheep, goats, or
wild ungulates; by EM demonstration of the poxvirus in the lesion; cell culture;
or serologically.
PREVENTION/CONTROL:
Wear rubber gloves when handling infected sheep and when working
in an environment near infected sheep.
MONKEY POX
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
Centers for Disease Control: Monkeypox: Updates/Advisories
Humanitarian Resource Institute: Monkeypox:
Biodefense and Epidemiological Tracking
AGENT:
Orthopoxvirus Disease in humans is indistinguishable from smallpox,
(Variola) i.e., serologic & clinical syndrome.
RESERVOIR
AND INCIDENCE
Animals: Nine reported outbreaks in captive NHP's, primarily rhesus
and cynomolgus. Has also been reported in languors, baboons, chimpanzees,
orangutans, marmosets, gorillas, gibbons, and squirrel monkeys. The virus
has been isolated from a wild squirrel. Man: The first human case of Monkey
Pox was reported in 1970. Between 1970 and 1986, over 400 cases had been reported
from tropical rain forested areas of West and Central Africa.
TRANSMISSION:
Transmission can be via direct contact, aerosol, ingestion, or
parenteral administration. Person to person transmission can occur.
DISEASE
IN NONHUMAN PRIMATES:
Usually exhibit a high morbidity and low mortality. Clinical signs
may be inapparent or an animal may exhibit fever, lymphadenopathy, and cutaneous
eruptions of the extremities, trunk, lips, or face. Cynos seem to be most
severely affected. Death is uncommon except in infant monkeys.
DISEASE
IN MAN:
Signs in man include fever, sore throat, headache, and a vesiculopustular
rash of peripheral distribution which clears up in 5 to 25 days. Severe
complications include bronchopneumonia, vomiting, and diarrhea. Case fatality
rate 10-15%. Although the disease is not common in man it is important from
the standpoint of differentiating it from smallpox.
DIAGNOSIS:
Based on progression of lesions, histopathology and virus isolation.
On histological examination epidermal cells contain eosinophilic cytoplasmic
and intranuclear inclusions. ELISA
TREATMENT:
Symptomatic.
PREVENTION/CONTROL:
Sanitation, isolation. Vaccination with vaccinia virus is protective
in both man and nonhuman primates.
YABAPOX
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
AGENT:
Poxvirus
RESERVOIR
AND INCIDENCE
Affects mangabeys, rhesus, cynos, vervets, stumptails, and patas
monkeys. Latent infection in African species that can infect Asian primates
and U.S. born African primates.
TRANSMISSION:
Need further clarification of the epidemiology of this disease.
Role of insect vectors has not been determined. Aerosol transmission has been
proven experimentally. *Transmission to humans from monkeys has not been
recorded. The virus can affect man usually after accidental skin puncture.
DISEASE
IN NONHUMAN PRIMATES:
Subcutaneous benign tumors (Histiocytomas) that may reach several
cm. in diameter. They usually regress spontaneously in 3 to 6 weeks.
DISEASE
IN MAN:
Lesions similar to those seen in monkeys
PREVENTION/CONTROL:
Usual care should be exercised by animal handlers, including wearing
of protective clothing.
TANAPOX
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Benign Epidermal Monkeypox, BEMP)
AGENT:
Tanapox virus.
RESERVOIR
AND INCIDENCE
Monkeys. In 1966 23 human cases were reported in the U.S. among
personnel who worked with monkeys affected at 3 primate centers. A serologic
study carried out on 263 monkeys of Asian origin (Macaca) revealed a 15% rate;
in 55 African Green Monkeys, the rate was 76%.
TRANSMISSION:
Aerosols or vectors. Human cases in the laboratory have resulted
from contamination of abrasions or scratches.
DISEASE
IN NONHUMAN PRIMATES:
Lesions occur primarily on the face, consisting of raised areas
with a central scab. Papules ulcerate, scab and heal.
DISEASE
IN HUMANS:
There is a fever for a few days, with headache and prostration
and a single skin vesicle. Cytoplasmic inclusions are seen in skin lesions.
Within 3 weeks of onset, the lesion spontaneously regresses.
DIAGNOSIS:
EM of skin scrapings or viral isolation.
TREATMENT:
Symptomatic.
PREVENTION/CONTROL:
Mosquito control. Asian and African monkeys should be housed separately.
Wear protective clothes.
HERPESVIRUSES
There are more than 35 Herpesviruses of NHPs most of which are
NOT zoonotic.
HERPES B
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Herpesvirus simiae, Simian B Disease)
AGENT:
Double-stranded DNA Virus. Direct zoonosis. For each Herpesvirus
there exists a host for which the virus is almost uniformly fatal and reservoir
hosts in which the virus exists in subclinical or latent infection. a. H.
suis latent in swine, fatal in cattle. b. H. simplex I latent in man, fatal
in Aotus, Gibbon, Marmoset (especially). c. H. saimiri I latent in Saimiri
sciureus, fatal in Marmosets, Aotus (also known as Herpes T, Herpes M, Herpes
Tamarinus). d. H. saimiri II latent in Saimiri sciureus, fatal in Marmosets,
Aotus (this is an oncogenic virus, causing Malignant Melanoma of Reticulum
Cell Type). e. H. simiae latent in rhesus and other macaques, fatal in man
(also known as Herpes B Virus). f. Liverpool Vervet Monkey Virus: reservoir
host ???, fatal in Cercopithecus aethiops. The Herpesviruses are serologically
distinct but do share some antigenic properties. Herpes B Virus has been
shown to have some antigenic relationship to Herpesvirus simplex by serum
neutralization tests. However, antibody from Herpesvirus simplex does not
confer immunity to Herpes B Virus.
RESERVOIR
AND INCIDENCE
Incidence of infection of the reservoir host is normally high but
you rarely see clinical disease. Clinical disease is usually confined to
the very young or to the immunologically compromised. On occasion lethal infection
occurs in the reservoir host: in humans, generalized Herpes simplex is often
fatal in infants; in swine, Herpes suis is fatal in piglets. Natural infection
does not result in elimination of the virus or in immunity but produces a
latent infection or carrier, which always makes vaccination of reservoirs
impractical. Herpesvirus B was first described in 1934 by Sabin/Wright. The
virus was recovered from a laboratory worker who had been bitten 18 days previously
by an apparently healthy rhesus. Since 1934, there have been 24 reported
cases, all fatal, except four. Of the four, only one is reasonably free of
severe neurological deficits. (Patients have remained in coma for as long
as 40 months prior to succumbing to the disease.) Incubation is considered
to be 10-20 days from exposure to the virus; however, in the Pensacola cases,
clinical disease occurred within 4-5 days of exposure. Contact with macaques
does not constitute exposure. The susceptibility of man to clinical B infection
is low although mortality is high.
TRANSMISSION:
direct contact, including sexual transmission, aerosols, and fomites.
THE DISEASE
IN NHP:
The reservoir hosts for Herpesvirus simiae are monkeys of the genus
Macaca. Monkeys incriminated include M. mulatta (rhesus), M. fascicularis
(cyno), M. fuscata (Japanese macaque), and M. arctoides (Stump-tail macaque).
B virus may produce mild cold-sore type lesions, primarily at mucocutaneous
junctions, mucous membranes, and tongue. But, it has been demonstrated that
infection is not confined to the mouth but can also be found in the genitalia.
These lesions are similar to those caused by Herpesvirus simplex I in man.
Two factors have been associated with antibody increases with age; 80-100%
of imported adult rhesus may have antibody compared to 20% imported juveniles.
The second factor was type of caging. Animals housed together had significantly
higher titers than individually-caged animals. Clinical disease may develop
at the time of primary infection but it is not known if lesions invariably
follow infection. However, periodic shedding of the virus may occur without
the presence of visible lesions. Once a monkey is infected with B Virus,
it should be considered infective for life.
THE DISEASE
IN MAN:
Human infection is characterized by encephalitis with diplopia;
nystagmus, patch paresthesia of head, neck and upper extremities. Acute abdominal
pain, fever and diarrhea have also been observed prior to neurologic symptoms.
Patients may also have a vesicular rash and/or keratoconjunctivitis. The
histopathological changes resemble those of fatal, systemic Herpesvirus simplex
in infants: encephalitis, myelitis and foci of necrosis in liver, spleen,
lymph nodes and adrenals. The case fatality rate is 70%.
DIAGNOSIS:
ELISA and viral isolation.
TREATMENT:
Acyclovir.
PREVENTION/CONTROL:
Control includes personal hygiene, protective clothing and common
sense in handling monkeys. The virus is susceptible to oxidizing agents, soap,
and water. Guidelines for prevention and treatment have been developed. The
reader is referred to the reference by Holmes, GP, et al for further details.
Emphasis can not be too strong concerning the use of protective clothing
when entering a room with macaques. A perfectly healthy monkey may be lethal
to you.
Arthropod borne ARBOVIRUSES:
Centers for Disease Control: Arboviral Encephalitides
Perspectives
Arthropod-borne
viruses, i.e., arboviruses, are viruses that are maintained in nature through
biological transmission between susceptible vertebrate hosts by blood feeding
arthropods (mosquitoes, psychodids, ceratopogonids, and ticks). Vertebrate
infection occurs when the infected arthropod takes a blood meal. The term
'arbovirus' has no taxonomic significance. Arboviruses that cause human
encephalitis are members of three virus families: the Togaviridae (genus
Alphavirus),
Flaviviridae, and Bunyaviridae.
All arboviral
encephalitides are zoonotic, being maintained in complex life cycles
involving a nonhuman primary vertebrate host and a primary arthropod vector.
These cycles usually remain undetected until humans encroach on a natural
focus, or the virus escapes this focus via a secondary vector or vertebrate
host as the result of some ecologic change. Humans and domestic animals can
develop clinical illness but usually are "dead-end" hosts because they do
not produce significant viremia, and do not contribute to the transmission
cycle. Many arboviruses that cause encephalitis have a variety of different
vertebrate hosts and some are transmitted by more than one vector. Maintenance
of the viruses in nature may be facilitated by vertical transmission (e.g.,
the virus is transmitted from the female through the eggs to the offspring).
Arboviral encephalitides
have a global
distribution, but there are four main virus agents of encephalitis in
the United States: eastern equine encephalitis (EEE), western equine encephalitis
(WEE), St. Louis encephalitis (SLE) and La Crosse (LAC) encephalitis, all
of which are transmitted by mosquitoes. Another virus, Powassan, is a minor
cause of encephalitis in the northern United States, and is transmitted by
ticks. A new Powassan-like virus has recently been isolated from deer ticks.
Its relatedness to Powassan virus and its ability to cause disease has not
been well documented. Most cases of arboviral encephalitis occur from June
through September, when arthropods are most active. In milder (i.e., warmer)
parts of the country, where arthropods are active late into the year, cases
can occur into the winter months.
The majority of
human infections are asymptomatic or may result in a nonspecific flu-like
syndrome. Onset may be insidious or sudden with fever, headache, myalgias,
malaise and occasionally prostration. Infection may, however, lead to encephalitis,
with a fatal outcome or permanent neurologic sequelae. Fortunately, only
a small proportion of infected persons progress to frank encephalitis.
Experimental
studies have shown that invasion of the central nervous system (CNS), generally
follows initial virus replication in various peripheral sites and a period
of viremia. Viral transfer from the blood to the CNS through the olfactory
tract has been suggested. Because the arboviral encephalitides are viral
diseases, antibiotics are not effective for treatment and no effective antiviral
drugs have yet been discovered. Treatment is supportive, attempting to deal
with problems such as swelling of the brain, loss of the automatic breathing
activity of the brain and other treatable complications like bacterial pneumonia.
There are no commercially
available human vaccines for these U.S. diseases. There is a Japanese encephalitis
vaccine available in the U.S. A tick-borne encephalitis vaccine is available
in Europe. An equine vaccine is available for EEE, WEE and Venezuelan equine
encephalitis (VEE). Arboviral encephalitis can be prevented in two major
ways: personal protective measures and public health measures to reduce the
population of infected mosquitoes. Personal measures include reducing time
outdoors particularly in early evening hours, wearing long pants and long
sleeved shirts and applying mosquito repellent to exposed skin areas. Public
health measures often require spraying of insecticides to kill juvenile (larvae)
and adult mosquitoes.
Selection of mosquito
control methods depends on what needs to be achieved; but, in most emergency
situations, the preferred method to achieve maximum results over a wide area
is aerial spraying. In many states aerial spraying may be available in certain
locations as a means to control nuisance mosquitoes. Such resources can be
redirected to areas of virus activity. When aerial spraying is not routinely
used, such services are usually contracted for a given time period.
Financing of aerial
spraying costs during large outbreaks is usually provided by state emergency
contingency funds. Federal funding of emergency spraying is rare and almost
always requires a federal disaster declaration. Such disaster declarations
usually occur when the vector-borne disease has the potential to infect large
numbers of people, when a large population is at risk and when the area requiring
treatment is extensive. Special large planes maintained by the United States
Air Force can be called upon to deliver the insecticide(s) chosen for such
emergencies. Federal disaster declarations have relied heavily on risk assessment
by the CDC.
Laboratory diagnosis
of human arboviral encephalitis has changed greatly over the last few years.
In the past, identification of antibody relied on four tests: hemagglutination-inhibition,
complement fixation, plaque reduction neutralization test, and the indirect
fluorescent antibody (IFA) test. Positive identification using these immunoglobulin
M (IgM) - and IgG-based assays requires a four-fold increase in titer between
acute and convalescent serum samples. With the advent of solid-phase antibody-binding
assays, such as enzyme-linked immunosorbent assay (ELISA), the diagnostic
algorithm for identification of viral activity has changed. Rapid serologic
assays such as IgM-capture ELISA (MAC-ELISA) and IgG ELISA may now be employed
soon after infection. Early in infection, IgM antibody is more specific,
while later in infection, IgG antibody is more reactive. Inclusion of monoclonal
antibodies (MAbs) with defined virus specificities in these solid phase
assays has allowed for a level of standardization that was not previously
possible.
Virus isolation
and identification have also been useful in defining viral agents in serum,
cerebrospinal fluid and mosquito vectors. While virus isolation still depends
upon growth of an unknown virus in cell culture or neonatal mice, virus identification
has also been greatly facilitated by the availability of virus-specific
MAbs for use in IFA assays. Similarly, MAbs with avidities sufficiently high
to allow for specific binding to virus antigens in a complex protein mixture
(e.g., mosquito pool suspensions) have enhanced our ability to rapidly identify
virus agents in situ. While polymerase chain reaction (PCR) has been developed
to identify a number of viral agents, such tests have not yet been validated
for routine rapid identification in the clinical setting.
Mosquito-borne
encephalitis offers a rare opportunity in public health to detect the risk
of a disease before it occurs and to intervene to reduce that risk substantially.
The surveillance required to detect risk is being increasingly refined by
the potential utilization of these new technologies which allows for rapid
identification of dangerous viruses in mosquito populations. These rapid
diagnostic techniques used in threat recognition can shorten public health
response time and reduce the geographic spread of infected vectors and thereby
the cost of containing them. The Arbovirus Diseases Branch of NCID's Division
of Vector-Borne Infectious Diseases has responsibility for CDC's programs
in surveillance, diagnosis, research and control of arboviral encephalitides.
La Crosse Encephalitis
La Crosse (LAC)
encephalitis was discovered in La Crosse, Wisconsin in 1963. Since then, the
virus has been identified in several Midwestern and Mid-Atlantic states. During
an average year, about 75 cases of LAC encephalitis are reported to the CDC.
Most cases of LAC encephalitis occur in children under 16 years of age. LAC
virus is a Bunyavirus and is a zoonotic pathogen cycled between the daytime-biting
treehole mosquito, Aedes triseriatus, and vertebrate amplifier hosts (chipmunks,
tree squirrels) in deciduous forest habitats. The virus is maintained over
the winter by transovarial transmission in mosquito eggs. If the female mosquito
is infected, she may lay eggs that carry the virus, and the adults coming
from those eggs may be able to transmit the virus to chipmunks and to humans.
Historically,
most cases of LAC encephalitis occur in the upper Midwestern states (Minnesota,
Wisconsin, Iowa, Illinois, Indiana, and Ohio). Recently, more cases are
being reported from states in the mid-Atlantic (West Virginia, Virginia
and North Carolina) and southeastern (Alabama and Mississippi) regions of
the country. It has long been suspected that LAC encephalitis has a broader
distribution and a higher incidence in the eastern United States, but is
under-reported because the etiologic agent is often not specifically identified.
LAC encephalitis
initially presents as a nonspecific summertime illness with fever, headache,
nausea, vomiting and lethargy. Severe disease occurs most commonly in children
under the age of 16 and is characterized by seizures, coma, paralysis, and
a variety of neurological sequelae after recovery. Death from LAC encephalitis
occurs in less than 1% of clinical cases. In many clinical settings, pediatric
cases presenting with CNS involvement are routinely screened for herpes
or enteroviral etiologies. Since there is no specific treatment for LAC encephalitis,
physicians often do not request the tests required to specifically identify
LAC virus, and the cases are reported as aseptic meningitis or viral encephalitis
of unknown etiology.
Also found in
the United States, Jamestown Canyon and Cache Valley viruses are related to
LAC, but rarely cause encephalitis.
Eastern Equine
Encephalitis
Eastern equine
encephalitis (EEE) is also caused by a virus transmitted to humans and equines
by the bite of an infected mosquito. EEE virus is an alphavirus
that was first identified in the 1930's and currently occurs in focal locations
along the eastern seaboard, the Gulf Coast and some inland Midwestern locations
of the United States. While small outbreaks of human disease have occurred
in the United States, equine epizootics can be a common occurrence during
the summer and fall.
It takes from
4-10 days after the bite of an infected mosquito for an individual to develop
symptoms of EEE. These symptoms begin with a sudden onset of fever, general
muscle pains, and a headache of increasing severity. Many individuals will
progress to more severe symptoms such as seizures and coma. Approximately
one-third of all people with clinical encephalitis caused by EEE will die
from the disease and of those who recover, many will suffer permanent brain
damage with many of those requiring permanent institutional care.
In addition to
humans, EEE virus can produce severe disease in: horses, some birds such as
pheasants, quail, ostriches and emus, and even puppies. Because horses are
outdoors and attract hordes of biting mosquitoes, they are at high risk of
contracting EEE when the virus is present in mosquitoes. Human cases are usually
preceded by those in horses and exceeded in numbers by horse cases which
may be used as a surveillance tool.
EEE virus occurs
in natural cycles involving birds and Culiseta melanura, in some swampy areas
nearly every year during the warm months. Where the virus resides or how
it survives in the winter is unknown. It may be introduced by migratory birds
in the spring or it may remain dormant in some yet undiscovered part of its
life cycle. With the onset of spring, the virus reappears in the birds (native
bird species do not seem to be affected by the virus) and mosquitoes of
the swamp. In this usual cycle of transmission, virus does not escape from
these areas because the mosquito involved prefers to feed upon birds and
does not usually bite humans or other mammals.
For reasons not
fully understood, the virus may escape from enzootic foci in swamp areas in
birds or bridge vectors such as Coquilletidia perturbans and Aedes sollicitans.
These species feed on both birds and mammals and can transmit the virus to
humans, horses, and other hosts. Other mosquito species such as Ae. vexans
and Culex nigripalpus can also transmit EEE virus. When health officials maintain
surveillance for EEE virus activity, this movement out of the swamp can be
detected, and if the level of activity is sufficiently high, can recommend
and undertake measures to reduce the risk to humans.
Western Equine
Encephalitis
The alphavirus
western equine encephalitis (WEE) was first isolated in California in 1930
from the brain of a horse with encephalitis, and remains an important cause
of encephalitis in horses and humans in North America, mainly in western parts
of the USA and Canada. In the western United States, the enzootic cycle of
WEE involves passerine birds, in which the infection is inapparent, and culicine
mosquitoes, principally Cx. tarsalis, a species that is associated with irrigated
agriculture and stream drainages. The virus has also been isolated from a
variety of mammal species. Other important mosquito vector species include
Aedes melanimon in California, Ae. dorsalis in Utah and New Mexico and Ae.
campestris in New Mexico. WEE virus was isolated from field collected larvae
of Ae. dorsalis, providing evidence that vertical transmission may play an
important role in the maintenance cycle of an alphavirus.
Expansion of irrigated
agriculture in the North Platte River Valley during the past several decades
has created habitats and conditions favorable for increases in populations
of granivorous birds such as the house sparrow, Passer domesticus, and mosquitoes
such as Cx. tarsalis, Aedes dorsalis and Aedes melanimon. All of these species
may play a role in WEE virus transmission in irrigated areas. In addition
to Cx. tarsalis, Ae. dorsalis and Ae. melanimon, WEE virus also has been
isolated occasionally from some other mosquito species present in the area.
Two confirmed and several suspect cases of WEE were reported from Wyoming
in 1994. In 1995, two strains of WEE virus were isolated from Culex tarsalis
and neutralizing antibody to WEE virus was demonstrated in sera from pheasants
and house sparrows. During 1997, 35 strains of WEE virus were isolated from
mosquitoes collected in Scotts Bluff County, Nebraska.
Human WEE cases
are usually first seen in June or July. Most WEE infections are asymptomatic
or present as mild, nonspecific illness. Patients with clinically apparent
illness usually have a sudden onset with fever, headache, nausea, vomiting,
anorexia and malaise, followed by altered mental status, weakness and signs
of meningeal irritation. Children, especially those under 1 year old, are
affected more severely than adults and may be left with permanent sequelae,
which is seen in 5 to 30% of young patients. The mortality rate is about
3%.
St. Louis Encephalitis
In the United
States, the leading cause of epidemic flaviviral encephalitis is St. Louis
encephalitis (SLE) virus. SLE is the most common mosquito-transmitted human
pathogen in the U.S. While periodic SLE epidemics have occurred only in the
Midwest and southeast, SLE virus is distributed throughout the lower 48
states. Since 1964, there have been 4,437 confirmed cases of SLE with an
average of 193 cases per year (range 4 - 1,967). However, less than 1% of
SLE viral infections are clinically apparent and the vast majority of infections
remain undiagnosed. Illness ranges in severity from a simple febrile headache
to meningoencephalitis, with an overall case-fatality ratio of 5-15 %. The
disease is generally milder in children than in adults, but in those children
who do have disease, there is a high rate of encephalitis. The elderly are
at highest risk for severe disease and death. During the summer season, SLE
virus is maintained in a mosquito-bird-mosquito cycle, with periodic amplification
by peridomestic birds and Culex mosquitoes. In Florida, the principal vector
is Cx. nigripalpus, in the Midwest, Cx. pipiens pipiens and Cx. p. quinquefasciatus
and in the western United States, Cx. tarsalis and members of the Cx. pipiens
complex.
Powassan Encephalitis
Powassan (POW)
virus is a flavivirus and currently the only well documented tick-borne transmitted
arbovirus occurring in the United States and Canada. Recently a Powassan-like
virus was isolated from the deer tick, Ixodes scapularis. Its relationship
to POW and its ability to cause human disease has not been fully elucidated.
POW's range in the United States is primarily in the upper tier States.
In addition to isolations from man, the virus has been recovered from ticks
(Ixodes marxi, I. cookei and Dermacentor andersoni) and from the tissues
of a skunk (Spiligale putorius). It is a rare cause of acute viral encephalitis.
POW virus was first isolated from the brain of a 5-year-old child who died
in Ontario in 1958. Patients who recover may have residual neurological problems.
Venezuelan
Equine Encephalitis
Like EEE and WEE
viruses, Venezuelan equine encephalitis (VEE) is an alphavirus and causes
encephalitis in horses and humans and is an important veterinary and public
health problem in Central and South America. Occasionally, large regional
epizootics and epidemics can occur resulting in thousands of equine and human
infections. Epizootic strains of VEE virus can infect and be transmitted
by a large number of mosquito species. The natural reservoir host for the
epizootic strains is not known. A large epizootic that began in South America
in 1969 reached Texas in 1971. It was estimated that over 200,000 horses
died in that outbreak, which was controlled by a massive equine vaccination
program using an experimental live attenuated VEE vaccine. There were several
thousand human infections. A more recent VEE epidemic occurred in the fall
of 1995 in Venezuela and Colombia with an estimated 90,000 human infections.
Infection of man with VEE virus is less severe than with EEE and WEE viruses,
and fatalities are rare. Adults usually develop only an influenza-like illness,
and overt encephalitis is usually confined to children. Effective VEE virus
vaccines are available for equines.
Enzootic strains
of VEE virus have a wide geographic distribution in the Americas. These viruses
are maintained in cycles involving forest dwelling rodents and mosquito vectors,
mainly Culex (Melanoconion) species. Occasional cases or small outbreaks
of human disease are associated with there viruses, the most recent outbreaks
were in Venezuela in 1992, Peru in 1994 and Mexico in 1995-96.
Other Arboviral
Encephalitides
Many other arboviral
encephalitides occur throughout the world. Most of these diseases are problems
only for those individuals traveling to countries where the viruses are endemic.
Japanese Encephalitis
Japanese encephalitis
(JE) virus is a flavivirus, related to SLE, and is widespread throughout
Asia. Worldwide, it is the most important cause of arboviral encephalitis
with over 45,000 cases reported annually. In recent years, JE virus has expanded
its geographic distribution with outbreaks in the Pacific. Epidemics occur
in late summer in temperate regions, but the infection is enzootic and occurs
throughout the year in many tropical areas of Asia. The virus is maintained
in a cycle involving culicine mosquitoes and waterbirds. The virus is transmitted
to man by Culex mosquitoes, primarily Cx. tritaeniorhynchus, which breed in
rice fields. Pigs are the main amplifying hosts of JE virus in peridomestic
environments.
The incubation
period of JE is 5 to 14 days. Onset of symptoms is usually sudden, with fever,
headache and vomiting. The illness resolves in 5 to 7 days if there is no
CNS involvement. The mortality in most outbreaks is less than 10%, but is
higher in children and can exceed 30%. Neurologic sequelae in patients who
recover are reported in up to 30% of cases. A formalin-inactivated vaccine
prepared in mice is used widely in Japan, China, India, Korea, Taiwan and
Thailand. This vaccine is currently available for human use in the United
States, for individuals who might be traveling to endemic countries.
Tick-Borne
Encephalitis
Tick-borne encephalitis
(TBE) is caused by two closely related flaviviruses which are distinct biologically.
The eastern subtype causes Russian spring-summer encephalitis (RSSE) and
is transmitted by Ixodes persulcatus, whereas the western subtype is transmitted
by Ixodes ricinus and causes Central European encephalitis (CEE). The name
CEE is somewhat misleading, since the condition can occur throughout much
of Europe. Of the two subtypes, RSSE is the more severe infection, having
a mortality of up to 25% in some outbreaks, whereas mortality in CEE seldom
exceeds 5%.
The incubation
period is 7 to 14 days. Infection usually presents as a mild, influenza-type
illness or as benign, aseptic meningitis, but may result in fatal meningoencephalitis.
Fever is often biphasic, and there may be severe headache and neck rigidity,
with transient paralysis of the limbs, shoulders or less commonly the respiratory
musculature. A few patients are left with residual paralysis. Although the
great majority of TBE infections follow exposure to ticks, infection has occurred
through the ingestion of infected cows' or goats' milk. An inactivated TBE
vaccine is currently available in Europe and Russia.
West Nile Encephalitis
WNV is a flavivirus
belonging taxonomically to the Japanese encephalitis serocomplex that includes
the closely related St. Louis encephalitis (SLE) virus, Kunjin and Murray
Valley encephalitis viruses, as well as others. WNV was first isolated in
the West Nile Province of Uganda in 1937 (2). The first recorded epidemics
occurred in Israel during 1951-1954 and in 1957. Epidemics have been reported
in Europe in the Rhone delta of France in 1962 and in Romania in 1996 (3-5).
The largest recorded epidemic occurred in South Africa in 1974 (6).
An outbreak of
arboviral encephalitis in New York City and neighboring counties in New York
state in late August and September 1999, was initially attributed to St.
Louis encephalitis virus based on positive serologic findings in cerebrospinal
fluid (CSF) and serum samples using a virus-specific IgM-capture enzyme-linked
immunosorbent assay (ELISA). The outbreak has been subsequently confirmed
as caused by West Nile virus based on the identification of virus in human,
avian, and mosquito samples. See also these MMWR articles Outbreak of West
Nile-Like Viral Encephalitis -- New York, 1999. MMWR, 1999:48(38);845-9 and
Update: West Nile-Like Viral Encephalitis -- New York, 1999. MMWR, 1999:48(39);890-2.
A recent outbreak WN encephalitis occurred in Bucharest, Romania in 1996.
The virus that
caused the New York area outbreak has been definitively identified as a strain
of WNV. The genomic sequences identified to date from human brain, virus
isolates from zoo birds, dead crows, and mosquito pools are identical. SLE
and West Nile viruses are antigenically related, and cross reactions are
observed in most serologic tests. The isolation of viruses and genomic sequences
from birds, mosquitoes, and human brain tissue permitted the discovery of
West Nile virus in North America and prompted more specific testing. The
limitations of serologic assays emphasize the importance of isolating the
virus from entomologic, clinical, or veterinary material.
Although it is
not known when and how West Nile virus was introduced into North America,
international travel of infected persons to New York or transport by imported
infected birds may have played a role. WNV can infect a wide range of vertebrates;
in humans it usually produces either asymptomatic infection or mild febrile
disease, but can cause severe and fatal infection in a small percentage
of patients. Within its normal geographic distribution of Africa, the Middle
East, western Asia, and Europe, WNV has not been documented to cause epizootics
in birds; crows and other birds with antibodies to WNV are common, suggesting
that asymptomatic or mild infection usually occurs among birds in those
regions. Similarly, substantial bird virulence of SLE virus has not been
reported. Therefore, an epizootic producing high mortality in crows and other
bird species is unusual for either WNV or SLE virus. For both viruses, migratory
birds may play an important role in the natural transmission cycles and spread.
Like SLE virus, WNV is transmitted principally by Culex species mosquitoes,
but also can be transmitted by Aedes, Anopheles, and other species. The predominance
of urban Culex pipiens mosquitoes trapped during this outbreak suggests an
important role for this species. Enhanced surveillance for early detection
of virus activity in birds and mosquitoes will be crucial to guide control
measures.
Related:
Murray Valley
Encephalitis
Murray Valley
encephalitis (MVE) is endemic in New Guinea and in parts of Australia; and
is related to SLE, WN and JE viruses. Inapparent infections are common, and
the small number of fatalities have mostly been in children.
YELLOW FEVER
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
yellow
fever
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Black Vomit)
AGENT:
RNA virus, Family Togaviridae, (Group B Arbovirus)
RESERVOIR
AND INCIDENCE
All primates susceptible; major Public Health problem in Central
and S. America and Africa.
TRANSMISSION:
Mosquito vector: Aedes and Hemagogues.
DISEASE
IN NONHUMAN PRIMATES:
There is high fever and vomiting, with jaundice, oliguria, and
generalized hemorrhages. Microglobular fatty degeneration of liver cells occurs
with disruption of the hepatic lobule and necrosis of midzonal liver cells,
producing so called "Councilman" bodies. Degeneration and necrosis of the
kidney tubules occurs. There are hemorrhages in tissues.
DISEASE
IN MAN:
Most cases have fever, severe headache and backache, jaundice and
albuminuria, followed by full recovery with a week, but in severe cases there
is a second episode of fever, prostration, jaundice, renal failure and generalized
hemorrhages. Microglobular fatty degeneration of liver cells occurs with
disruption of the hepatic lobule and necrosis of midzonal liver cells, producing
so called "Councilman" bodies. Degeneration and necrosis of the kidney tubules
occurs. There are hemorrhages in tissues. The case fatality rate among indigenous
populations of endemic regions is <5%, but may exceed 50% among nonindigenous
groups and in epidemics.
DIAGNOSIS:
Virus isolation or serology.
TREATMENT:
Consists of limiting food to high-carbohydrate, high-protein liquids,
IV glucose and saline, analgesics and sedatives, and saline enemas.
PREVENTION/CONTROL:
Monkeys should originate from a yellow fever free area, or be maintained
in a double-screened mosquito-proof enclosure, or have been immunized against
yellow fever. For humans, mosquito control, vaccination, and adherence to
PHS quarantine standards.
HANTAVIRUS PULMONARY SYNDROME
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
hantavirus
pulmonary syndrome
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
INTRODUCTION:
On May 14, 1993, the New Mexico Department of Health was notified
of 2 persons who had died within 5 days of each other. Their illnesses were
characterized by abrupt onset of fever, myalgia, headache, and cough, followed
by the rapid development of respiratory failure. Tests for Yersinia pestis
and other bacterial and viral pathogens were negative. After additional persons
who had recently died following a similar clinical course were reported
by the Indian Health Service, the health services of Arizona, Colorado and
Utah were contacted to seek other possible cases. Blood and tissue specimens
were sent to the Centers for Disease Control and Prevention (CDC). The results
were negative except for signals for the Puumala hantavirus. Relying on molecular
and immunological research performed by the Army, the National Institutes
of Health, and the CDC itself, by June 9th, the CDC was able to prove that
a new hantavirus was the culprit (1). As of November 5th, laboratory evidence
of acute hantavirus infection had been confirmed in 42 persons. Twenty-six
(62%) of these persons have died. Most cases were in the Southwest but some
have been reported as far afield as North Dakota and California (1). This
paper presents a brief overview of hantavirus infections with primary focus
on Hantavirus Pulmonary Syndrome (HPS) and recommended laboratory precautions
to reduce the risk of accidental exposure. Other detailed reviews are available
elsewhere (2-7).
AGENT:
Isolation of the first recognized hantavirus (Hantaan virus) was
reported from the Republic of Korea in 1978. The genus Hantavirus is a member
of the family Bunyaviridae. Hantaviruses are further divided into genotypes.
Representative viruses in each genotype are the Hantaan virus, the Seoul
virus, the Puumala virus, and the Prospect Hill virus. Additional groups exist.
Hantaan, Puumala, and Seoul viruses are known human pathogens; Prospect Hill
has not been associated with disease. The causative agent of HPS represents
a previously unidentified genotype. Since the 1930s, epidemic and sporadic
hantavirus-associated disease has been described throughout Eurasia, especially
in Scandinavia and Northeastern Asia. In the 1950s, thousands of United Nations
military personnel were infected with hantavirus during the Korean conflict;
more recently, transmission has been documented among United States military
personnel training in the Republic of Korea. Hantaviruses have been isolated
from rodents in the United States, and serological studies have documented
human infections with hantaviruses. However, acute disease associated with
infection by pathogenic hantaviruses has not previously been reported in
the Western Hemisphere (8). Previously called the Four Corners Virus and
Muerto Canyon Virus, the causative genotype for HPS is now called Sin Nombre
Virus.
DISEASE
IN HUMANS:
The clinical manifestations previously associated with hantavirus
infections have been characterized by hemorrhagic features and by renal involvement.
In HPS, however, onset of illness has been characterized by a prodrome consisting
of fever, myalgia, and variable respiratory symptoms followed by the abrupt
onset of acute respiratory distress. Other symptoms reported during the
early phase of illness have included headache and gastrointestinal complaints.
Hemoconcentration and thrombocytopenia have developed in a majority of the
cases. The hospital course has been characterized by bilateral pulmonary
infiltration, fever, hypoxia, and hypotension; recovery in survivors has
been without sequelae. It is important to note that no defined set of symptoms
and signs reliably distinguishes HPS from other forms of noncardiogenic pulmonary
edema or adult respiratory distress syndrome (9). Postmortem examination
has routinely revealed serous pleural effusions and heavy edematous lungs.
Microscopic findings have included interstitial infiltrates of mononuclear
cells in the alveolar septa, congestion, septal and alveolar edema with or
without mononuclear cell exudate, focal hyaline membranes, and occasional
alveolar hemorrhage. Large mononuclear cells with the appearance of immunoblasts
have been found in red and periarteriolar white pulp of the spleen, hepatic
portal triads, and other sites. Hantavirus antigens, localized primarily
in endothelial cells, have been detected in most organs, with marked accumulations
in the lungs (9). The incubation period for the known pathogenic hantaviruses,
although highly variable, generally range from 2 to 4 weeks (8). Based on
reported cases, the incubation period for HPS appears to be one to three
weeks (10).
RESERVOIRS:
Rodents are the primary reservoir hosts with each hantavirus appearing
to have a preferential rodent host. The epidemiological characteristics of
outbreaks of human disease and the severity for the infection are determined
mainly by the rodent host. Available data strongly supports the deer mouse
(Peromyscus maniculatus) as the primary reservoir of the newly recognized
hantavirus (11). Serologic evidence of infection has also been found in
pi¤on mice (P. truei) and the brush mice (P. boylii). Other rodent
species that have tested positive so far include the house mouse (Mus musculus),
the harvest mouse (Reithrodontomys sp.), the rock squirrel (Spermophalus
variegatus), the white-throated wood rat (Neotoma albigula), and the western
chipmunk (Tamias spp.). P. maniculatus is highly adaptable and is found in
different habitats, including human residences in rural and semirural areas,
but generally not in urban centers (12). The wood mouse or striped field
mouse (Apodemus sp.) associated hantaviruses also cause severe human disease
with mortality rates between 3 and 7%. Rattus associated disease is less
severe and asymptomatic infections may be more common. The most benign form
of hantaviral disease (HVD), also called Nephropathia epidemica and first
described in Scandinavia, is caused by a hantavirus that infects voles (Clethrionomys
species). Infected voles and human disease occur throughout western Europe
(13). The hantaviruses have been identified in other animals. At the International
Symposium on Hemorrhagic Fever with Renal Syndrome (HFRS), Leningrad, 5-10
May 1991, the presence of hantaviral antigen was reported in 13 species of
birds in eastern parts of the former U.S.S.R. (13). The CDC is also investigating
whether other animals, particularly those that prey on rodents, may carry
the virus. The impetus for this research is a 1987 study suggesting that
cats, which tested positive for two other hantaviruses-the Hantaan and Seoul
types-may help transmit the virus to humans in China. As for the HPS virus,
so far CDC scientists have identified one infected nonrodent species (aside
from humans): the desert cottontail (Sylvilagus auduboni). But virologists
think most nonrodents are "dead-end" hosts that shed little virus and are
unlikely to infect people (14). Laboratory rats, which were a reservoir of
hantavirus, have been responsible for several outbreaks of HVD among animal
caretakers and laboratory workers at research institutions in Korea, China,
the former Soviet Union, Japan, Scandinavia, the U.K., France, the Netherlands
and Belgium (13). Transmission of Hantavirus from laboratory reared mice
and rats has not been documented in the United States.
TRANSMISSION:
Susceptibility of rodents may vary depending on the combination
of rodent species and virus strains; however, Hantaviruses do not cause apparent
illness in their reservoir hosts (15). In rodents, the virus is detected primarily
in the lung and kidney, where it persists despite the presence of serum antibodies.
Infected rodents shed large quantities of virus in saliva, urine, and feces
for many weeks, but the duration and period of maximum infectivity are unknown.
Although the main route of transmission is aerosolization, the demonstrated
presence of infectious virus in saliva of infected rodents and the marked
sensitivity of these animals to hantaviruses following inoculation suggests
that biting may also be an important mode of transmission among rodents (12).
Arthropod vectors are not known to have a role in the transmission of hantaviruses.
Domestic animals may bring infected rodents into contact with humans (12).
Human infection may occur when infective saliva or excreta are inhaled as
aerosols produced directly from the animal. Transmission may also occur when
dried materials contaminated by rodent excreta are disturbed, directly introduced
into broken skin, introduced onto the conjunctivae, or, possibly, ingested
in contaminated food or water. Persons have also become infected after being
bitten by rodents (12). Person-to-person transmission has not been associated
with any of the previously identified hantaviruses nor with the recent outbreak
in the Southwest (16). In the current epidemic, known hantavirus infections
of humans have occurred primarily in adults and are associated with domestic,
occupational, or leisure activities that bring humans into contact with infected
rodents, usually in a rural setting. Cases have been epidemiologically associated
with the following situations: Planting or harvesting field crops Occupying
previously vacant cabins or other dwellings Cleaning barns and other outbuildings
Disturbing rodent-infested areas while hiking or camping Inhabiting dwellings
with indoor rodent populations Residing in or visiting areas in which the
rodent population has shown an increase in density (12). In Europe, isolation
of hantaviruses from immunocytomas and ascites tumors has highlighted additional
risks from working with persistently infected rodents. Tumors, passaged over
the years in hantavirus-infected laboratory rats, transfer the virus when
implanted in hantavirus-free rats. Since, in rodents, hantaviruses are not
transmitted vertically but horizontally, the use of caesarian section and
foster mother techniques have been recommended for laboratories breeding
rodent colonies. Before implantation, tumors should be checked for the presence
of the hantaviruses (this precaution should be followed by laboratory workers
in the U.S. importing tumors, organs, or live rodents from hantavirus endemic
areas) (12).
DIAGNOSIS:
The CDC in consultation with the Council of State and Territorial
Epidemiologists has developed screening criteria for HPS (9). Cases meeting
the screening criteria should be reported to the CDC through state health
departments. These criteria are: Potential case-patients must have one of
the following: a febrile illness (temperature ò101 oF [ò38.3
oC]) occurring in a previously healthy person characterized by unexplained
adult respiratory distress syndrome, or bilateral interstitial pulmonary infiltrates
developing within 1 week of hospitalization with respiratory compromise requiring
supplemental oxygen, OR an unexplained respiratory illness resulting in death
in conjunction with an autopsy examination demonstrating noncardiogenic
pulmonary edema without an identifiable specific cause of death. Potential
case-patients are to be excluded if they have any of the following: a predisposing
underlying medical condition (e.g., severe underlying pulmonary disease,
solid tumors or hematologic malignancies, congenital or acquired immunodeficiency
disorders, or medical conditions [e.g., rheumatoid arthritis or organ transplant
recipients] requiring immunosuppressive drug therapy [e.g., steroids or cytotoxic
chemotherapy]). an acute illness that provides a likely explanation for the
respiratory illness (e.g., recent major trauma, burn, or surgery; recent
seizures or history of aspiration; bacterial sepsis; another respiratory
disorder such as respiratory syncytial virus in young children; influenza;
or legionella pneumonia). Confirmed case-patients must have the following:
at least one specimen (i.e., serum and/or tissue) available for laboratory
testing for evidence of hantavirus infection. AND in a patient with a compatible
clinical illness, diagnosis is confirmed when any of the following criteria
are met: IgM antibodies to hantavirus antigens, fourfold or greater increase
in immunoglobulin G titers to hantavirus antigens in paired serum specimens,
a positive immunohistochemical stain for hantavirus antigen in tissues, or
positive polymerase chain reaction (PCR) for hantavirus ribonucleic acid.
Currently, diagnosis of the HPS strain of Hantavirus in animals is in its
infancy. IFA based tests offered by national research laboratories may be
used for screening; however, false negatives can occur depending on the antigen
used. PCR remains the method of choice for strain identification. Presently,
one laboratory (Rockefeller University Laboratory Animal Research Center,
[212]327-8522) offers this service with more, hopefully, coming on line in
the future (17).
TREATMENT:
Supportive care and meticulous monitoring of vital signs and fluid
balance are the basis for therapy. Severe hypoxia and overhydration should
be avoided or prevented. Pressors or cardiotonic drugs should be employed
to maintain perfusion without excessive fluid administration (9). In one controlled
study involving HFRS, intravenous administration of the antiviral drug ribavirin
was effective in treating severe cases of hantavirus infection when administered
early in the course of illness (8). The effectiveness of using ribavirin
to treat HPS has not been established, yet.
PREVENTION
AND CONTROL:
Hantaviruses have lipid envelopes that are susceptible to most
disinfectants (e.g., dilute hypochlorite solutions, detergents, ethyl alcohol
(70%), or most general-purpose household disinfectants). How long these viruses
survive after being shed in the environment is uncertain (12). The reservoir
hosts of the hantavirus in the southwestern United States also act as hosts
for the bacterium Yersinia pestis, the etiology agent of plague. Although
fleas and other ectoparasites are not known to play a role in hantavirus
epidemiology, rodent fleas transmit plague. Control of rodents without concurrent
control of fleas may increase the risk of human plague as the rodent fleas
seek an alternative food source. Thus, eradicating the reservoir hosts of
hantaviruses is neither feasible nor desirable. Once the virus has been
cultured, it might be possible to develop a vaccine against the HPS strain.
However, currently, the best available approach for disease control and prevention
is risk reduction through environmental hygiene practices that deter rodents
from colonizing the home and work environment (12). No restriction of travel
to areas affected by this outbreak is considered necessary; however, activities
that may disrupt rodent burrows or result in contact with rodents or aerosolization
or rodent excreta should be avoided. Laboratory workers practicing universal
precautions while processing routine clinical materials (such as blood, urine,
and respiratory specimens) are not considered to be at increased risk for
hantavirus infection. However, laboratory-acquired infections have occurred
among persons who handled infected wild or laboratory rodents. Therefore,
laboratory work that may result in propagation of hantaviruses should be
conducted in a special facility (biosafety level 3) (8). Recommendations
for laboratory animal facilities housing wild-caught rodents include: Access
to rooms should be restricted to only those individuals who have a legitimate
need to be in the room. Colony should be serologically screened for the agent.
Animals should be housed and handled under standard microisolation techniques.
Biological safety cabinets should be used and not laminar flow workbenches.
Until the status of the colony can be ascertained, individuals working with
the rodent should: a. Obtain a baseline serum sample. The serum should be
stored at -20oC. b. Insure that all persons involved are informed of the
symptoms of the disease and given detailed guidance on prevention measures.
c. Seek immediate medical attention if a febrile or respiratory illness develops
within 45 days of the last potential exposure. The attending physician should
be informed of the potential occupational risk of hantavirus infection. d.
Wear an half-face air-purifying (or negative-pressure) respirator or powered
air-purifying respirator with HEPA filter when handling rodents or their
cages. Respirators are not considered protective if facial hair interferes
with the face seal. Respirators should be fitted by trained personnel in
accordance with OSHA standards. e. Wear rubber or plastic gloves when handling
rodents or cages. Gloves should be washed and disinfected before removing
them. f. Wear dedicated outer garments (disposable, if possible), rubber
boots or disposable shoe covers and protective goggles. Personal protective
gear should be decontaminated upon removal. If not disposable, they should
be laundered on site using hot water and detergent. Machine-dry using a high
setting. If no laundry facilities are available, non-disposable items should
be immersed in liquid disinfectant until they can be washed. All potentially
infective waste material (including respirator filters, bedding, caging,
disposable protective garments, and used disposables such as syringes, gauze,
etc.) should be placed in autoclavable plastic bags and sterilized. Needles,
scalpels, pipettes, and other sharp materials should be placed in puncture
proof containers and sterilized. Spread from feral rodents was postulated
as the cause of one source of contamination (18). Therefore, facilities
and individual rooms should be vermin-proof to prevent accidental egress
and ingress of rodents. All openings greater than ¬ inch should be screened
or sealed. Carcasses should be placed in a plastic bag and disposed as biohazard
waste or incinerated. Since feral rodents may transmit the disease, it is
recommended that Hantavirus testing be included in animal health monitoring
programs. Why the Current Epidemic? Because of the rodent connection with
this disease, medical investigators and public health officials sought ecological
information on the deer mouse and other native rodent species. Anecdotal
information from residents in the afflicted areas suggested that rodents
were exceptionally abundant last winter, and scientists speculated that,
if true, the increased potential for rodent-human contact and disease transmission
might account for the sudden epidemic. Biologists with the Sevilleta, New
Mexico Long-Term Ecological Research (LTER) site have long-term data on rodent
communities in the region. At the request of the CDC and the New Mexico Health
Department, LTER researchers provided detailed demographic analyses from
1989-1993 for the 22 rodent species inhabiting the area. The LTER data showed
tenfold population increases in various Peromyscus species and wood rats
(Neotoma spp.) during the spring of 1993. Population increases occurred simultaneously
in grasslands, desert-shrublands, and woodlands. Comparisons of the rodent
data to the region's climatological data indicated that rodent population
dynamics is associated with above-average precipitation during the winter
of 1992-93, in turn leading to abundant food sources (19).
References
- Marshall, E. 1993. Hantavirus outbreak yields
to PCR. Science. 262:832-836.
- LeDuc, J. W., J. E. Childs, and G. E. Glass.
1992. The Hantaviruses, etiologic agents of hemorrhagic fever with renal syndrome.
Annu Rev Public Health. 13:79-98.
- Niklasson, B. S. 1992. Hemorrhagic fever
with renal syndrome, virological and epidemiological aspects. Pediatr Nephrol.
6(2):201-204.
- Cosgriff, T. M. and R. M. Lewis. 1991. Mechanisms
of disease in hemorrhagic fever with renal syndrome. Kidney Int Suppl. 35:S72-79.
- Tkachenko E. A. and H. W. Lee. 1991. Etiology
and epidemiology of hemorrhagic fever with renal syndrome. Kidney Int Suppl.
35:S54-61.
- Beaty, B. J. and C. H. Calisher. 1991. Bunyaviridae--natural
history. Curr Top Microbiol Immunol. 169:27-78.
- Gonzalez-Scarano, F., M. J. Endres, and N.
Nathanson. 1991. Bunyaviridae: Pathogenesis. Curr Top Microbiol Immunol. 169:217-249.
- 1993. Emerging infectious diseases. Outbreak
of acute illness. Wkly Epidemiol Rec. 68(25):186-8.
- 1993. Emerging infectious diseases. Update:
Hantavirus Disease. MMWR. 42(29, 31, and 42).
- Sands, L. 1993. Guidelines for
DIAGNOSIS:
and treatment of unexplained adult respiratory distress syndrome.
Arizona Department of Health Services.
- Nichol, S. T., C. F. Spiropoulou, S. Morzunov, et al. 1993. Genetic
identification of a Hantavirus associated with an outbreak of acute respiratory
illness. Science. 262:914-917.
- 1993. Hantavirus infection-Southwestern United
States: interim recommendations for risk reduction. MMWR. 42(RR-11).
- McKenna, P., G. VanDerGroen, G. Hoofd, et
al. 1992. Eradication of hantavirus infection among laboratory rats by application
of caesarian section and a foster mother techniques. J Infect. 25:181-190.
- Stone, R. 1993. The mouse-pi¤on nut
connection. Science. 262:833.
- Kawamura, K., X. K. Zhang, J. Arikawa, et
al. 1991. Susceptibility of laboratory and wild rodents to Rattus or Apodemus-type
hantaviruses. Acta Virol. 35:54-63.
- Hughes, J. M., C. J. Peters, M. L. Cohen,
et al. 1993. Hantavirus pulmonary syndrome: an emerging infectious disease.
Science. 262:850-851.
- Morse, S. 1994. Personal communication.
- Wong, T. W., Y. C. Chan, E. H. Yap, et al.
1988. Serological evidence of Hantavirus infection in laboratory rats and
personnel. Int J Epidemiol. 17(4):887-890.
- Dybas, C. 1993. NSF-funded researchers find
rodent population explosion may be behind hantavirus epidemic in southwest.
NSF Bulletin #93-59.
HEMORRHAGIC FEVER WITH RENAL SYNDROME [HFRS]
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Korean Hemorrhagic Fever, Nephropathia Epidemica, Epidemic Hemorrhagic
Fever, Hemorrhagic Nephrosonephritis)
AGENT:
Bunyaviridae family, Hantaan virus genus
RESERVOIR
AND INCIDENCE
Recognized originally in troops serving in the Korean war. Named
Hantaan after river in endemic area of Korea. Isolated in 1978 in Apodemus
agrarius, then adapted to tissue culture and laboratory rats. Serologic mapping
indicates that Hantaviruses have infected large numbers of people in the region
from Japan across central and north Asia to the Scandinavian Peninsula, and
southward in Europe to the Balkans. Other Hantaviruses have been identified
in urban rats captured in major Asian and Western cities, including the USA
and Brazil. Hosts of hantavirus are wild Rodents Several antigenic subtypes
exist, each associated with a single rodent species: Apodemus species -
Striped field mouse - A. agrarius (Korea) associated with KHF. Domestic Rattus
norvegicus and Rattus rattus in Korea and Domestic Rattus norvegicus in the
U.S. had virus similar to prototype Hantaan virus yet distinct from it. Microtus
pennsylvanicus: the meadow vole. Reservoir for Prospect Hill virus, most
recently isolated Hantavirus. Isolated at NIH and named for Prospect Hill
in Frederick, MD where the vole was captured that yielded the first isolate.
No human disease associated with this so far but antibody has been identified
among mammalogists in the U.S.(1982). Cletheronomys glareolus: the bank vole.
Reservoir for Puumala virus, cause of Nephropathia epidemica (NE), a mild
form of HFRS found in Scandinavia, Western Soviet Union and much of Europe.
TRANSMISSION:
Aerosol transmission from rodent excreta is presumed. Virus is
present in urine, feces and saliva of persistently infected asymptomatic rodents;
highest virus concentration is found in the lungs. Human to human transmission
does not occur.
DISEASE
IN RODENTS:
Chronic, ASYMPTOMATIC infection. Following infection, rodent is
viremic for about 1 week when virus is disseminated throughout the body. After
viremia antigen is usually abundant in the lungs, spleen and kidneys. Antibody
is produced and persists but does not diminish the abundance of antigen expressed
in organs.
DISEASE
IN MAN:
Symptoms begin with the sudden onset of fever which lasts 1-2 weeks,
accompanied by prostration, anorexia, generalized pains, conjunctivitis,
proteinuria and hypotension, possibly followed by hemorrhages and hematuria
with renal failure. Case fatality rate is 7%.
DIAGNOSIS:
Serology using indirect immunofluorescence or ELISA.
TREATMENT:
IV ribavirin
PREVENTION/CONTROL:
Although most US commercial animal breeders have eliminated these
viruses through barrier breeding and caesarean derivation, small suppliers
and producers of select inbred strains may be at risk of infection. Be aware
of potentially infected animals when receiving shipments from Japan, Belgium
or other countries which may have the agent present in lab. animals (where
virus-free certification cannot be provided). Animals should be serologically
tested in advance of shipment. Test all rodent tissues, tumors, cell lines
received from source that cannot provide virus free certification. Education
and awareness of potential problem. Exclude rodents from housing and other
buildings in endemic areas.
OTHER HEMORRHAGIC FEVERS
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
arenavirus
infections
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Arenaviruses) All have natural persistent infection in rodents
with humans being accidental hosts. Route of transmission to humans is generally
thought to occur thru contamination of food, water, or air by rodent feces
or urine or by inoculation of skin abrasions. Humans are infected primarily
through infected rodents invading human habitats. Contact with infected rodent
feces has produced disease in laboratory personnel.
DIAGNOSIS:
By serology or virus isolation. Control is to reduce opportunity
for exposure to infected rodents. 1. JUNIN VIRUS: produces Argentinian hemorrhagic
fever There is an illness of 1-2 weeks with insidious onset of fever, malaise,
rigors, fatigue, headache, vomiting, constipation or diarrhea, conjunctival
congestion, retro-orbital pain, epistaxis, petechial hemorrhages beneath
skin, palate and gums. Edema of the upper body is possible. In severe cases
hematemesis and melena, encephalopathy, bradycardia and hypertension occur.
Case fatality rate 5-30%. Several hundred cases reported each year in Argentina.
Associated with at least 3 different cricetine rodent species in Argentina
2. MACHUPO VIRUS: produces Bolivian Hemorrhagic fever Signs and case fatality
rate like Junin virus. Case #s have been decreasing rapidly since initiation
of rodent control programs in 1975. Associated with Calomys callosus (Bolivia).
3. LASSA FEVER: Serologically related to Lymphocytic Choriomeningitis, Machupo,
and Junin virus. Fever has insidious onset over 2-3 days and may persist for
up to 4 weeks, with malaise, headache and generalized aching and sore throat.
Vomiting and diarrhea, possibly edema of face and neck, lymphadenopathy with
hemorrhages and renal failure occurs in the second week. The prostration is
out of proportion to fever. Often there is a maculopapular rash. Occurs in
large areas in West Africa. Documented man to man transmission. Found in
common rodent Mastomys natalensis, multimammate rat (West Africa).
LYMPHOCYTIC CHORIOMENINGITIS - LCM
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
AGENT:
Arenavirus Of many latent viruses present in mice, only LCM naturally
infects humans. LCM can easily be transmitted from animals to humans. Isolated
by Armstrong and Lillie during investigation of a St. Louis Encephalitis outbreak
in 1933.
RESERVOIR
AND INCIDENCE
Worldwide in wild mice (M. musculus). This disease is principally
confined to the eastern seaboard and northeastern states in the U.S. Wild
mice infect the lab mouse. Mouse and hamster are the only species in which
long term, asymptomatic infection is known to exist. *LCM virus is present
in experimental mouse tumors which is a second source of infection for humans.
This was first recognized in a transplantable leukemia of C58 mice. The disease
can also be transmitted to laboratory animals via inoculation of infected
tissue culture cells. The infection also occurs in guinea pigs, rabbits, rats,
canines, swine, and primates.
TRANSMISSION:
Infection in mice is maintained by congenital infection followed
by lifelong carriage and excretion of virus in saliva, urine, and feces. Human
infections are probably from contaminated food and dust, the handling of
dead mice, and mouse bites. Bloodsucking arthropod vectors such as ticks,
lice, and mosquitos may transmit the disease. Person to person transmission
does not occur.
DISEASE
IN ANIMALS:
The clinical signs of LCM depend on the host's resistance and age
when infected, although the various categories of the disease are not always
clearly delineated. Animals infected in utero or during the first 48 hours
postpartum may develop a transient viremia but recover completely within
a few weeks. Other animals similarly infected may develop a persistent tolerant
infection (PTI) that continues asymptomatically for 6 or more months. Animals
infected after the first few days, when the virus will be recognized as foreign,
often overcome the infection completely, but an acute, usually fatal syndrome
can develop. Signs of acute infection in mice continue for 1-2 weeks and
include decreased growth, rough hair coat, hunched posture, blepharitis,
weakness, photophobia, tremors, and convulsions. The terminal stage of the
PTI, which occurs over several weeks to 5 to 12 month old mice, is characterized
by weight loss, blepharitis, and impaired reproductive performance and runted
litters. The important necropsy signs are microscopic. Visceral organs,
including the liver, kidneys, lungs, pancreas, blood vessels, and meninges,
are infiltrated by lymphocytes. A glomerulonephritis of probable immune
complex origin is a characteristic feature of terminal PTI.
DISEASE
IN MAN:
The features may include influenza-like illness for up to 2 weeks,
possibly with orchitis. Sometimes meningitis, paralysis and coma follow. Joint
pains occur during convalescence.
DIAGNOSIS:
CF or virus isolation.
PREVENTION/CONTROL:
Serologic monitoring Infection can be eradicated by cesarean derivation
prevent wild mice from entering facilities control ectoparasites and roaches
Restrict flow of traffic into and out of LCM infected colonies Protective
clothing and proper care when handling infected animals or tissues. Basic
hygienic practices Screen tissue culture cell lines and murine tumor lines
and animals periodic serologic testing of high risk personnel
CALIFORNIA ENCEPHALITIS/LA CROSSE ENCEPHALITIS
Centers for Disease Control and Prevention: Division of Vector-Borne
Infectious Diseases
La
Crosse encephalitis
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(USA) (Tahyna virus [Europe]) A mild, febrile, viral disease which
occasionally causes severe encephalitis. It is transmitted by mosquitoes
from small wild mammals, mainly in summer, to persons frequenting woodland
areas of the USA and Canada, and certain European countries such as Yugoslavia
and the USSR. The causative agents are the California encephalitis group
of viruses (Bunyaviridae). There is no vaccine.
RESERVOIR
AND MODE OF TRANSMISSION:
The virus cycles amongst small wild animals (e. chipmunks, squirrels,
rabbits and hares) and a variety of mosquito species. The infection can be
maintained independently over several years by transovarial transmission
in the mosquito. Humans are accidental hosts infected by mosquito bite during
occupational or recreational activities in wooded areas. Accidental infections
from laboratory accidents have occurred.
INCUBATION
PERIOD:
Humans. 5-15 days. Animals. Unknown.
CLINICAL
FEATURES:
Humans. Symptoms lasting about 5-10 days range from fever and headache
with nausea and vomiting to fits and signs of aseptic meningitis, encephalitis
and neurological sequelae. Animals. Unknown but assumed subclinical.
PATHOLOGY:
Humans. Encephalitis. Animals. Unknown.
DIAGNOSIS:
:Humans. The virus may sometimes be isolated from blood or rarely,
from cerebrospinal fluid. Serologic tests of blood or cerebrospinal fluid
may be diagnostic in specific types of encephalitis (by demonstrating virus-specific
IgM or a fourfold change in complement-fixing or neutralizing antibodies).
Animals. Impracticable.
PROGNOSIS:
In humans, fatality is rare but neurological defects may persist.
Animals. Thought to be subclinical.
PREVENTION:
Humans. Prevent mosquito bites. Control the mosquito vector. Apply
laboratory safety procedures. Animals. Impracticable.
TREATMENT:
Humans. Vigorous symptomatic therapy. Such measures include reduction
of intracranial pressure (Mannitol), monitoring of intraventricular pressure,
the control of convulsions, maintenance of the airway, administration of oxygen,
and attention to adequate nutrition during periods of prolonged coma. Animals.
Not applicable.
LEGISLATION:
Humans. Acute encephalitis is notifiable in many countries, including
the USA and the UK. Animals.None.
MARBURG VIRUS
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
Marburg
virus infection
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(African Hemorrhagic Fever, Green or Vervet Monkey Disease)
AGENT:
Agent is classified as a Filovirus. It is an RNA virus, superficially
resembling rhabdoviruses but has bizarre branching and filamentous or tubular
forms shared with no other known virus group on EM.
RESERVOIR
AND INCIDENCE
An acute highly fatal disease first described in Marburg, Germany
in 1967. Brought to Marburg in a shipment of infected African Green Monkeys
from Uganda. 31 people were affected and 7 died in 1967. Exposure to tissue
and blood from African Green monkeys (Cercopithecus aethiops) or secondary
contact with infected humans led to the disease. No disease occurred in
people who handled only intact animals or those who wore gloves and protective
clothing when handling tissues. A second outbreak was reported in Africa
in 1975 involving three people with no verified contact with monkeys. Third
and fourth outbreaks in Kenya 1980 and 1987. Natural reservoir is unknown.
Monkeys thought to be accidental hosts along with man. Antibodies have been
found in African Green monkeys, baboons, and chimpanzees. 100% fatal in experimentally
infected African Green Monkeys, Rhesus, squirrel monkeys, guinea pigs, and
hamsters.
TRANSMISSION:
Direct contact with infected blood or tissues or close contact
with infected patients. Virus has also been found in semen, saliva, and urine.
DISEASE
IN NONHUMAN PRIMATES:
No clinical signs occur in green monkeys, but the disease is usually
fatal after experimental infection of other primate species. Leukopenia and
petechial hemorrhages throughout the body of experimentally infected monkeys,
sometimes with GI hemorrhages.
DISEASE
IN MAN:
5-7 day incubation period. Headache, fever, muscle pain, vomiting,
diarrhea, hemorrhagic diathesis, Conjunctivitis, photophobia, skin rash, and
jaundice. Leukopenia, thrombocytopenia, proteinuria. Shock and death in 25%
of cases. Hemorrhages throughout the body on post mortem examination.
DIAGNOSIS:
IFA, ELISA, Western blot, EM, or virus isolation.
TREATMENT:
Supportive Possibly immune serum
PREVENTION/CONTROL:
Strict quarantine on newly imported, wild-caught primates. Naturally
infected monkeys should become ill or die within several weeks. Hygiene,
sanitation, and protective clothing Isolation of human patients with prevention
of sexual intercourse until semen is free of virus.
EBOLA
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
Ebola hemorrhagic
fever
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(African Hemorrhagic Fever)
AGENT:
Similar to Marburg morphologically similar but antigenically distinct.
Both are RNA Filoviruses and have bizarre branching and filamentous or tubular
forms shared with no other known virus group.
RESERVOIR
AND INCIDENCE
Reservoirs unknown. Monkeys are probably accidental hosts, along
with humans. First recognized in 1976 in Northern Zaire and Southern Sudan,
500 cases with 350 deaths reported.
TRANSMISSION:
Person-to-person transmission occurs by direct contact with infected
blood, secretions, organs or semen. Nosocomial infections have been frequent;
all Zaire cases acquired from contaminated syringes and needles died.
DISEASE
IN MAN:
Fever, headache, malaise, followed by chest discomfort, diarrhea,
and vomiting. Case fatality rate is 50-90%.
DIAGNOSIS:
IFA, ELISA, Western blot, EM, or virus isolation.
TREATMENT:
Supportive Possibly immune serum
PREVENTION/CONTROL:
Strict quarantine on newly imported, wild-caught primates. Naturally
infected monkeys should become ill or die within several weeks. Hygiene ,sanitation,
and protective clothing Isolation of human patients with prevention of sexual
intercourse until semen is free of virus.
RABIES
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
rabies
Office International des Epizooties
Rabies:
Manual of standards Diagnostic Tests and Vaccines 2000
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Hydrophobia, Lyssa)
AGENT:
Rhabdovirus which causes an acute almost invariably fatal disease.
RESERVOIR
AND INCIDENCE
Worldwide distribution (few countries are exceptions) Primary reservoirs
vary geographically, eg. foxes, bats, raccoons, skunks, dogs, cats, cattle,
and others. In the U.S. and Canada, wildlife rabies most frequently involves
skunks, raccoons, and bats. There has been a progressive epizootic among
raccoons in the eastern U.S. for over a decade. Involve wild and domestic
species. Mostly wild species involved, only 10% of cases are in domestic animals
16 cases have been confirmed in nonhuman primates, including chimpanzees,
cebus, cynos, and squirrel monkeys. All source countries of NHP's have endemic
rabies. In Germany, Paarman described 25 Avian cases of Rabies involving
11 chickens, 2 geese, 1 duck, 1 sparrow, 1 owl, 1 crow, 3 hawks, 1 kite,
1 magpie, and 4 buzzards with Negri bodies observed in only three. In the
U.S., the Great Horned Owl may shed the virus in its droppings after consuming
an infected skunk. Rodents and lagomorphs are unlikely to have rabies. In
the U.S., rabies has been reported 13 times in ferrets since 1958, most often
in pet ferrets acquired from pet shops.
TRANSMISSION:
Virus laden saliva via bite, scratch, or abrasion Tissues and fluids
in the laboratory Rabid dogs shed virus in saliva 5-7 days before showing
signs. Cat does so for only 3 days before signs. Aerosol transmission has
been documented in the laboratory and in caves where bats roost (requires
a high concentration of suspended viral particles). Animals showing signs
of rabies are usually shedding large amounts of virus.
DISEASE
IN ANIMALS:
Rabid animals of all species exhibit typical signs of CNS disturbance,
with minor variations peculiar to carnivores, ruminants, bats, and man. The
clinical course, particularly in dogs, can be divided into 3 phases: the
prodromal, the excitative, and the paralytic. The term "furious rabies"
refers to animals in which the excitative phase is predominant, and "dumb
or paralytic rabies" to those in which the excitative phase is extremely
short or absent and the disease progresses quickly to the paralytic phase.
In any animal, the first sign is a change in behavior, which may be indistinguishable
from a GI disorder, injury, foreign body in the mouth, poisoning, or an early
infectious disease. Temperature change is not significant, and driveling
may or may not be noted. Animals usually stop eating and drinking and may
seek solitude. Frequently, the urogenital tract is irritated or stimulated
as evidenced by frequent urination, erection in the male, and sexual desire.
After the prodromal period of 1-3 days, animals either show signs of paralysis
or become vicious. Carnivora, pigs, and occasionally, horses and mules bite
other animals or people at the slightest provocation. Cattle butt any moving
object. The disease progresses rapidly after the onset of paralysis, and
death is virtually certain within 10 days of the first signs. Rabid domestic
cats and bobcats attack suddenly, biting and scratching viciously. Rabid
foxes frequently invade yards or even houses, attacking dogs and people.
The irrationality of behavior that can occur is demonstrated in the fox that
attacks a porcupine; finding a fox with porcupine quills can, in most cases,
support a diagnosis of rabies. Rabid foxes and skunks are responsible for
most pasture cattle losses, and have attacked cattle in barns. The rabid
raccoon is characterized by its loss of fear of man, its frequent aggression
and incoordination, and its activity during the day, being predominantly
a nocturnal animal. In urban areas, they often attack domestic dogs. Bats
flying in the daytime are probably rabid.
DISEASE
IN MAN:
There is usually a history of animal bite. Pain appears at the
site of the bite, followed by paresthesias. The skin is quite sensitive to
changes of temperature, especially air currents. Attempts at drinking cause
extremely painful laryngeal spasm, so that the patient refuses to drink (hydrophobia).
The patient is restless and behaves in a peculiar manner. Muscle spasm, laryngospasm,
and extreme excitability are present. Convulsions occur. Large amounts of
thick tenacious saliva are present.
DIAGNOSIS:
Consider Rabies as a possible problem in any wild caught or random-source
laboratory animal of unknown vaccination history showing central nervous
system signs or symptoms. Virus isolation from body fluid or tissue Fluorescent
antibody (FA) staining of tissues, including cornea, frozen skin, mucosal
scrapings, as well as brain. Highly specific & rapid. Can now detect
different strains (ie skunk vs raccoon origin) via monoclonal antibody analysis
which is specific for one antigenic focus on the viral particle. The identifiable
strains correlate well with species and geographic distributions observed.
This allows identification of source and is an important epidemiologic tool.
(5 strains have been isolated from terrestrial animals; 2 skunk, 1 raccoon,
1 gray fox, 1 red fox, More than 5 have been isolated from bats.)
TREATMENT:
This very severe illness with an almost universally fatal outcome
requires skillful intensive care with attention to the airway, maintenance
of oxygenation, and control of seizures.
PREVENTION/CONTROL:
Virus is destroyed rapidly at greater than 50 C and survives no
more than a few hours at room temperature (Can persist for years in frozen
tissues) Vigorous first aid for bite wounds. Consult Health Authority if suspected
exposure. Postexposure immunization: Up to 50% of human rabies immune globulin
is infiltrated around the wound; the rest is administered IM. Human Diploid
Cell Vaccine (HDCV) is given as 5 injections IM at days 0, 3, 7, 14, and
28. Control disease in domestic animals by vaccination and enforced animal
control measures. Discourage keeping of wild animals as pets. Discourage
the vaccination of wild animal pets for rabies. Vaccination of high risk
personnel.
HEPATITIS A
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
hepatitis
A
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Infectious hepatitis, Epidemic hepatitis, Epidemic jaundice)
AGENT:
Family Picornaviridae, Genus enterovirus
RESERVOIR
AND INCIDENCE
More than 200 cases of hepatitis A virus infection in humans have
been associated with nonhuman primates, principally chimpanzees but also woolly
and patas monkeys, Celebes apes, siamangs, and gorillas. Man, and, rarely
captive chimpanzees are the reservoir host; less frequently, certain other
nonhuman primates. An enzootic focus has been identified in Malaysia, but
there is no suggestion of transmission to man.
TRANSMISSION:
Although transmission of the virus may occur by contaminated needles,
it is usually by the fecal-oral route. Nonhuman primates acquire the disease
from man.
DISEASE
IN NONHUMAN PRIMATES:
Usually do not show clinical signs, although malaise, vomiting,
and jaundice have been reported. Disease is detected by elevated liver enzymes
or diagnostic liver biopsies. Usually a self-limiting disease.
DISEASE
IN MAN:
Fever, malaise, anorexia, headache, muscle pain, abdominal discomfort,
and jaundice. Liver enzymes are elevated along with LDH, bilirubin, and alkaline
phosphatase. Morbidity is variable and mortality is 0.6% Development of
antibody confers lifelong immunity.
DIAGNOSIS:
RIA or ELISA
TREATMENT:
Bed rest, IV fluids if dehydrated.
PREVENTION/CONTROL:
Strictly quarantine newly arrived chimps and allow only limited
human contact for at least 45-60 days. Protective clothing (gown, gloves,
& mask) Routine disinfection of equipment and personal hygiene. Administer
immune serum to handlers of newly imported chimpanzees (0.02ml/kg) every 3
mos. or 0.06 ml/kg every 4 months. Vaccine being developed.
MEASLES
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
measles
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Rubeola, Morbilli)
AGENT:
Family Paramyxoviridae, Genus Morbillivirus. The same genus contains
the viruses of Canine Distemper and Bovine Rinderpest.
RESERVOIR
AND INCIDENCE
Man is the only known reservoir. New world monkeys are more resistant
than old world monkeys but exhibit high mortality when infected.
TRANSMISSION:
Virus is excreted from the mucous membranes of the eye and pharynx
and later from the respiratory and urinary tracts. Virus is shed in the prodromal
phase and continues through the exanthematous phase. Highly contagious!
Can spread from man to monkey, monkey to monkey, man to man, and monkey to
man.
DISEASE
IN NONHUMAN PRIMATES:
Many infections occur subclinically. Rash, fever, facial edema,
giant cell pneumonia, conjunctivitis, nasal discharge.
DISEASE
IN MAN:
Incubation period 10-14 days. Conjunctivitis Koplik spots - bluish
white spots on buccal mucosa 2-3 days after onset Leukopenia Rash in mouth,
cheeks, neck, chest, and body. Can be complicated by middle ear infection,
bronchopneumonia, encephalitis Fetal risk if contracted during pregnancy.
The mortality rate in children in the U.S. is 0.2%, but may be as high as
10% in developing countries.
DIAGNOSIS:
Clinical signs, serology, histopath.
TREATMENT:
Bed rest, acetaminophen, saline eye sponges, nose drops. Vitamin
A (400,000 IU/day) has been shown to reduce pediatric morbidity and mortality.
PREVENTION/CONTROL:
Vaccinate personnel working with nonhuman primates (Live attenuated
measles vaccine) if they do not have: 1. a titer to rubeola (HI >1:4 protective)
2. confirmed history of previous vaccination 3. confirmed prior disease Live
attenuated measles vaccine can be given to macaques but causes disease and
death in marmosets and owl monkeys.
CYTOMEGALOVIRUS DISEASE
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
Cytomegalovirus
infection
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
Most cytomegalovirus infections in healthy individuals are asymptomatic,
with the virus remaining (exact cells of latency are not known). However
the virus is isolable from up to 25% of salivary glands, 10% of uterine cervices,
and 1% of neonatal urine samples. Seroprevalence increases with age and
the number of sexual partners; detectable antibody is present in the serum
of most homosexual men. Transmission is sexual, congenital, through or transplantation,
and person-to-person (e.g., day care centers). Severe disease occurs primarily
in the immunocompromised, especially those with AIDS and transplant patients.
DISEASE
IN MAN:
A. Classification: There are three recognizable syndromes. 1. Perinatal
disease and cytomegalovirus inclusion disease-Intrauterine infection of infants
whose mothers had a primary infection during pregnancy results in a neonatal
syndrome of jaundice, hepatosplenomegaly, thrombocytopenia, periventricular
central nervous system calcifications, mental retardation, motor disability,
and purpura.
DIAGNOSIS:
Confirmed by viruria within the first week after birth or serum
IgM antibodies to cytomegalovirus. Hearing deficits occur in over 15% and
mental retardation in up to 30%. Neonatally acquired disease may resemble
mononucleosis; while it is often asymptomatic, neurologic deficits may ensue
later in life. 2. Acute acquired cytomegalovirus infection--This syndrome,
akin to EBV-associated infectious mononucleosis, is characterized by fever,
malaise, myalgias and arthralgias (but not pharyngitis or respiratory symptoms),
atypical lymphocytes, and abnormal liver function tests. Unlike EBV-associated
infectious mononucleosis, the heterophil antibody is not found. Transmission
can be by sexual contact, by milk, by respiratory droplets (probably) among
nursery or day care center attendants, and by (usually massive) transfusions
of blood. 3. Disease in immunocompromised hosts-Tissue and bone marrow transplant
patients are at increased risk for CMV infection, especially in the first
I 00 days after allograft transplantation. HIV-infected patients may have
a variety of CMV manifestations. Cytomegalovirus is itself immunosuppressive
and may worsen manifestations of HIV infection, including Pneumocystis carinii
pneumonia. a. CMV retinitis-Retinitis due to CMV infection occurs primarily
in AIDS patients. Screening for visual symptoms may be helpful, but ophthalmologic
documentation of neovascular, proliferative lesions ("pizza-pie" retinopathy)
is required for diagnosis. b. Gastrointestinal and hepatobiliary CMV-Serious
gastrointestinal CMV disease occurs in AIDS and after organ transplantation,
cancer chemotherapy, or steroid therapy. Esophagitis presents with odynophagia;
small bowel disease may mimic inflammatory bowel disease or may present as
ulceration or perforation. Colonic CMV disease causes diarrhea, hematochezia.
abdominal pain, fever, and weight loss. Pancreatitis, when not due to pentamidine,
didanosine, or (less often) zalcitabine is often due to cytomegalovirus; hepatobiliary
involvement often includes other pathogens, including Cryptosporidium. Diagnosis
is by mucosal biopsy that shows characteristic CMV histopathologic findings
of intranuclear ("owl's eye") and intracytoplasmic inclusions. c. Pulmonary
CMV-Pulmonary CMV infection occurs in about 15% of bone marrow transplant
recipients: the mortality rate is 80-90% in this group. CMV seronegative
blood products should be used in seronegative recipients of seronegative
transplants. High-titer CMV immunoglobulins may be effective in preventing
CMV pneumonia in the seronegative recipients. d. Neurologic CMV-Polyradiculopathy
and encephalitis have been reported but are not common. When they do occur,
there is often concomitant retinitis, which may be subclinical. Prolonged
ganciclovir may be helpful, and treatment should be continued indefinitely.
DIAGNOSIS:
Cytomegalovirus is isolable from urine, cervical secretions, semen,
saliva, blood, and other tissues, but virus isolation is most useful when
combined with pathologic findings, including large cells with intranuclear
and intracytoplasmic inclusions that resemble owl's eyes: cultures alone are
of little use in diagnosing AIDS-related cytomegalovirus infections. Retinitis
among aids patients is diagnosed clinically. The acute mononucleosis syndrome
is associated with a lymphocytosis, often 2 weeks after the fever. Serologic
tests (IFA and the anticomplement immunofluorescent antibody [ACIF]) are
useful primarily in seroepidemiologic studies. In AIDS patients, titers may
be depressed, and seroconversions are seldom documented, with most seroconversions
having occurred in the past. Antigen detection by virus technology (including
the polymerase chain reaction technique) must be interpreted in the context
of clinical and pathologic findings.
TREATMENT:
Two antiviral agents with efficacy against cytomegalovirus are
ganciclovir, given in a dosage of 5 mg/kg IV every 12 hours for 14-21 days
(maintenance: 5-7 mg/kg/day for 5 days each week, with dose reduction for
renal impairment); and foscarnet, given as a loading dose of 20 mg/kg IV and
then 60 mg/kg every 8 hours over 2 weeks (maintenance: 120 mg/kg/day). The
induction phase is essential for AIDS patients with cytomegalovirus disease
involving critical parts of the retina; for less critical areas, maintenance
therapy can be used from the outset. Both agents are effective in preventing
progression of retinitis, and ganciclovir is useful in cytomegalovirus colitis;
treatment is usually lifelong in patients with AIDS. Complications include
neutropenia with ganciclovir (preventing concomitant zidovudine therapy)
and renal impairment with foscarnet (often manageable with hydration).
CONTROL:
Cytomegalovirus hyperimmune globulin given to seronegative bone
marrow or renal transplant recipients may be prophylactic. Limiting transfusions,
using products filtered to remove leukocytes, and selecting cytomegalovirus-seronegative
donors are all important in reducing the rate of cytomegalovirus transmission.
INFLUENZA
Centers for Disease Control: Influenza:
Updates/Advisories
Humanitarian Resource Institute: Influenza:
Biodefense and Epidemiological Tracking
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Swine and Equine Influenza, Fowl Plague)
AGENT:
The causative agent is influenza type A (Orthomyxoviridae).
RESERVOIR
AND INCIDENCE
Humans, wild and domestic birds, horses and pigs are reservoirs
of influenza viruses, which appear to be species specific. Convalescent carriers
act as reservoir hosts between epidemics. Antigenic shift is probably required
before animal virus becomes epidemic in humans. Sporadic human infections
with swine and avian strains have been reported. Human cases of influenza
have occurred from contamination by aerosols from infected ferrets and vice
versa.
TRANSMISSION:
Transmission is by inhalation of droplets produced by coughing
and sneezing, especially in crowded, enclosed spaces.
DISEASE
IN ANIMALS:
Fever has a sudden onset followed by anorexia, coughing, respiratory
distress and mucoid nasal discharge, with rapid recovery. There is consolidation
in the lung. Copious mucopurulent exudate fills the bronchioles.
DISEASE
IN HUMANS:
Typical symptoms include fever, chills, headache, myalgia, malaise,
coryza, pharyngitis and cough with full recovery within two weeks, although
viral or secondary bacterial pneumonia may develop, especially in the elderly.
DIAGNOSIS:
Virus isolation, CF or HI serology.
TREATMENT:
Bed rest, analgesics, and cough mixtures. Amantadine decreases
duration by 50%. Antibiotics are reserved for bacterial complications. Ribavirin
aerosol has helped severely ill patients.
PREVENTION/CONTROL:
Polyvalent human influenza vaccine provides partial immunity (about
85% efficacy) for a few months to one year. The vaccine's antigenic configuration
changes yearly and is based on prevalent strains of the preceding year.
Chemoprophylaxis with amantadine will markedly reduce the attack rate among
exposed individuals if begun immediately and continued for 10 days. Vaccinate
horses annually. Prohibit imports of live poultry and poultry meat from
countries where fowl plague occurs.
SEVERE ACUTE RESPIRATORY SYNDROME (SARS)
World Health Organization: Severe Acute Respiratory Syndrome
(SARS)
U.S. Centers
for Disease Control: Severe Acute Respiratory Syndrome
(SARS)
SARS, an atypical pneumonia of unknown aetiology, was recognized
at the end of February 2003. The World Health Organization (WHO) is co-ordinating
the international investigation with the assistance of the Global Outbreak
Alert and Response Network and is working closely with health authorities
in the affected countries to provide epidemiological, clinical and logistical
support as required.
PREVENTION/CONTROL:
WHO
biosafety guidelines for handling of SARS specimens: 25 April 2003
NEWCASTLE DISEASE
Office International des Epizooties
Newcastle
disease: Manual of standards Diagnostic Tests and Vaccines 2000
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Pseudo Fowl Pest)
AGENT:
Newcastle disease virus, family Paramyxoviridae
RESERVOIR
AND INCIDENCE
The natural reservoir is wild and domesticated birds.
TRANSMISSION:
Transmission is by inhalation of infectious aerosols. Intensive
conditions favor spread by contact, on inanimate objects and airborne between
poultry houses. Human infections occur mainly amongst laboratory workers and
those who work with infected chickens or who give live vaccine, especially
by aerosol.
DISEASE
IN ANIMALS:
In poultry, respiratory and nervous signs occur, including gasping
and coughing; also drooping of wings, twisting of the head and neck; inappetence
and paralysis. Egg production ceases. Petechial hemorrhages are characteristic,
especially in the preventricular mucosa. Necrosis of the intestinal mucosa
give a "bran" like appearance. Congestion and mucoid exudate appears in the
lungs and bronchi.
DISEASE
IN HUMANS:
Usually symptoms are confined to painful conjunctivitis lasting
a few days, but fever and influenza-like symptoms for up to 3 weeks may follow.
DIAGNOSIS:
Virus isolation or ELISA.
TREATMENT:
Symptomatic.
PREVENTION/CONTROL:
Hygienic precautions are needed when handling infected birds. Avoid
inoculation injuries and ensure laboratory safety. Maintain strict hygiene
in poultry sheds and quarantine of imported live birds, prohibit importation
from infected countries, sterilization of, or prohibition on, waste food
fed to poultry. Vaccination of poultry.
OTHER SPECULATIVE VIRAL ZOONOSES:
ROTAVIRUS:
Centers for Disease Control and Prevention: National Center for
Infectious Diseases
rotavirus
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
Rotaviruses cause gastroenteritis in animals and humans. They are
not strictly species-specific, and experimental cross-infections with human
or animal rotaviruses in several animal species have been confirmed. The
finding of serotypes common to man and various animal species might indicate
that some serotypes can infect both. However, the natural occurrence of cross-infections
between species and the possible role of animals in the epidemiology of the
disease in humans are still unknown.
RETROVIRUSES:
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
The human immunodeficiency viruses (HIVs)-acquired immunodeficiency
syndrome (AIDS) or HAIDS pandemic originated from lentiviruses of nonhuman
primates (thus qualifying as a zoonosis) that moved into humans in Africa.
The HAIDS patients eventually die of opportunistic infections, all potentially
zoonotic. The HAIDS infection remained parochial, first endemically and
then epidemically, until the African urbanization that occurred in each
of the countries postindependence. The latter included wars and the massive
movement of soldiers (virologically naive) from the American continent to
Africa and back. The HAIDS viral ecology coincided with African swine fever
(ASF) in the Americas. Haiti became the focal point for both infections.
Some infected Haitians also became, together with some infected drug addicts
in the United States, a source of contaminated human blood for transfusions
and production of plasma derivatives.
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