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Zoonoses
Zoonoses are diseases of animals
that are transmissible to humans. They
may be a significant exposure hazard in some laboratories where animals
are used for research. Fortunately, many laboratory animal species
today are bred to be free of zoonoses that were once more common in
these
animals. However, there remain zoonotic agents associated with laboratory
animals, some which can be life-threatening. Field research with wild species
also remains a clear source of zoonoses exposure. Prevention of exposure
to these animal-related illnesses requires knowledge of the zoonoses related
to the animals with which you will be working. In the sections that
follow, the zoonotic agents listed for each animal species are those that may
be present in the animals being used. If you are e
xposed through bite,
scratch, aerosol droplet, mucosal secretion, feces or urine, there is the potential
for you to become infected, and medical consultation through Employee Health
at McCosh Health Center is
highly recommended.
Zoonoses - Mice & Rats (top)
 Mice
Laboratory Mice:
 Modern
laboratory mice are bred to exclude all zoonotic agents. Also,
mice received at Princeton University from foreign countries have
been tested during quarantine for a large number of infectious
and zoonotic agents. Therefore, unless the laboratory mice
are exposed to wild mice (those coming from the natural habitat
outside the laboratory), there is limited concern for disease from
these research mice. However, there is always concern about
secondary infections that can occur with bites and scratches. Common
skin, intestinal, and soil bacteria present on you or the animal
can infect the scratch or bite wound and cause these secondary
infections. Therefore, you should handle all mice with
care and always cleanse any wound immediately with soap and water
or antiseptic and seek medical consultation for severe wounds.
Wild Mice:
Wild mice or laboratory mice that have been exposed
to wild mice may have the potential of carrying a
variety of zoonotic bacteria
and viruses
that can be passed on to those handling them. Tests are completed on wild
mice and those coming from foreign countries when they are received
in Princeton labs to screen for these zoonotic agents. Although
this provides reasonable assurance that mice will be free of zoonotic infections,
the screening does not guarantee infection-free mice. Therefore,
because of the serious consequences of becoming infected, you must always
follow
good personal hygiene and animal handling procedures and use the provided
PPE to
protect yourself from exposure.
Mice that have originated from the wild, or have
had contact with wild mice, or are from foreign countries could
be infected with
one or more of the illness
agents described here:
HANTAVIRUS
Hantavirus is transmitted through inhalation
of dried rodent feces and urine when such material is raised into
the air
from disturbed bedding
or nesting
material. Transmission can also occur through rodent bites and contamination
of broken skin or mucous membranes. The infection progresses from flu-like
symptoms to respiratory complications and has resulted in death over 50%
of the cases, particularly when medical care was not quickly
obtained. You can prevent exposure through the use of provided
PPE, good personal hygiene, and wet, properly ventilated handling of
waste bedding
material.
LYMPHOCYTIC CHORIOMENINGITIS (LCM) VIRUS
LCM virus is
transmitted to humans by inhalation, broken skin or mucous membrane
exposure to blood, urine, feces,
and other body secretions
from
infected mice. The infection results in flu-like symptoms
1 to 3 weeks after exposure. More severe symptoms of
meningitis and encephalitis can result. There is a special
risk of exposure during pregnancy because
the fetus can become infected. Because mice are well-screened
and provided from virus-free sources, the potential for exposure
in Princeton University
animal facilities is very limited. Again, use of proper
PPE, such as disposable gloves and lab coat along with careful
hand washing
will further
reduce the likelihood
of exposure.
 Rats
Modern laboratory rats are bred to exclude all zoonotic
agents. Therefore,
unless the laboratory rats are exposed to wild rodents (those coming from
the natural habitat outside the laboratory), there is limited concern for disease
from these research rats. However, there is always concern about secondary
infections that can occur with bites and scratches. Common skin, intestinal,
and soil bacteria present on you or the animal can infect the scratch or
bite wound and cause these secondary infections. Therefore,
you should handle all rats with care and always cleanse any wound
immediately
with
soap and water
or antiseptic and seek medical consultation
for severe wounds
Historically, rats have been known to carry the bacteria that causes Rat-Bite
Fever. However, these bacteria have not been found in laboratory
rats for decades due to the special efforts of commercial suppliers
to eliminate this bacteria from breeding colonies.
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Zoonoses - Rabbits, Birds and Fish
 Rabbits
Modern laboratory rabbits contain few infectious pathogens.
Of concern are scratches that can be inflicted with their
strong
hind legs and sharp
claws or from bites. Secondary infection with common skin, intestinal,
and soil bacteria present on you or the animal can result, so always cleanse
wounds immediately with soap and water or antiseptic and seek medical consultation
for severe wounds.
Historically, laboratory rabbits have been known to harbor the
bacteria
for human Tularemia (Rabbit Fever). Although this zoonotic agent
remains present in wild rabbit populations, modern laboratory rabbits are free
of this illness bacteria.
 Birds
The birds used in research colonies are either caught in the
wild
or acquired from established flocks. In general, birds are not supplied
disease-free, and usually contain a number of microbial agents. Of zoonotic
concern are the diarrheal bacteria, such as Salmonella that cause intestinal
illness and the bacteria that causes psittacosis, which can cause a more severe
type of infection
SALMONELLA
Salmonella bacteria
is a common contaminate of fecal droppings
and eggs. When ingested by humans,
this bacteria
has the potential for causing severe
intestinal disease. Use of good personal hygiene measures, including
effective and
thorough hand washing along with the proper
PPE, such as disposable gloves and
lab coat, will greatly
reduce the
likelihood of infection when handling
birds and materials in their environment.
PSITTACOSIS
The bacteria Chlamydia
psittaci is the
cause of psittacosis,
and it is found most widely in large, imported
psittacine birds (i.e. parrots,
parakeets, cockatoos, macaws). Human infection is most
often the result of exposure to these imported birds. The
risk of exposure from domestic birds is very low. However,
because this bacteria is highly infectious, there is some
potential that any bird or mammal
may
be infected. Acute infection in animals causes
such symptoms as reddening of the eyes (conjunctivitis),
difficulty breathing pneumonia),
swollen painful joints (arthritis), and reproductive problems. After
the acute infection, those animals that survive enter a period
without symptoms during
which stress can cause the animal to shed the bacteria. (Stress
can result from such things as the importation process or
birds being handled in their new
environment.) Humans can be infected when
coming in contact with the bird’s body secretions, or feces. In
humans, the symptoms include fever, headache, muscle pain,
chills. If left untreated, the infection may cause pneumonia, liver, heart, and brain inflammation.
USDA regulations require that testing
be performed on all psittacine birds imported
from foreign countries during an initial 60 day quarantine
period. Such birds are quarantined in specially ventilated
rooms while testing is done and infected birds require
elimination from the
colony. This
testing is done for such birds housed in Princeton University
facilities, so infected birds should not pose a significant
exposure hazard. If
you are handling birds, use of protective apparel and thorough
hand washing will reduce the risk of any potential exposure.
Fish and Amphibians
Fish and amphibians used in research colonies
are mostly wild-caught or raised on commercial
farms. These animals often contain
parasites and bacteria. Of zoonotic concern
are gram negative bacteria that will cause secondary
infection of contaminated
wounds and breaks in the
skin. These bacteria include Aeromonas,
Pseudomonas, Klebsiella, and Mycobacteria. Use
of proper PPE, such as disposable gloves, will help prevent
contamination of
skin surfaces. Likewise, thorough
hand washing is very
important to further reduce potential for infection.
Zoonoses - Bats
 Bats
Laboratory-housed bats have been procured from established lab colonies where they had been held for experimental uses for 2 years without any evidence of disease associated with them. The source of these bats greatly reduces the likelihood that they carry rabies, the principle zoonoses of concern related to bats.
Exposure to wild bat roosts and handling of bats in the field presents a greater potential for exposure to rabies and the fungal disease histoplasmosis. Because the wild bats may have a greater potential to carry rabies virus or generate histoplasmosis spores in fecal-contaminated soil, there is greater need for care in handling of the animals and in disturbing and cleaning of fecal-contaminated roosts.
Bat bites and scratches and wound and mucous membrane exposure to bat saliva are the ways in which rabies can be transmitted. Spores of histoplasmosis can be present in soil and debris enriched with bird and bat droppings. When this dry soil is disturbed, spores can become airborne and cause infection by inhalation. In enclosed spaces where these conditions are present, it is important that protective clothing and dust mask be worn and that potentially-contaminated soil and debris that will be disturbed be moistened with water spray to control dust dispersion.
RABIES
Rabies is a preventable virus disease that causes an inflammation of the brain, and is almost always fatal once symptoms develop. Rabies is transmitted through the saliva of infected, warm-blooded animals. Worldwide, dogs are the most common source of rabies. In the United States, skunks, raccoons, foxes, coyotes, and bats are the main source of rabies infections. Most people who get rabies have been bitten by an infected animal, but getting the infected saliva from an infected animal into an open wound or mucous membrane of eyes, nose, or mouth can also lead to infection. Rabies is not spread by contact with bat feces, blood, or urine.
Rabies virus infects the central nervous system, causing brain inflammation and ultimately death. Early symptoms of rabies in humans are nonspecific, consisting of fever, headache, and general malaise. As the disease progresses, neurological symptoms appear and may include insomnia, anxiety, confusion, slight or partial paralysis, excitation, hallucinations, agitation, hypersalivation, difficulty swallowing, and hydrophobia (fear of water). Death usually occurs within days of the onset of symptoms.
Rabies can be preventedby avoiding contact with infected animals, and providing pre-exposure and/or post-exposure vaccination to those who have high-risk contact with animals presumed to be infected.
Post-exposure treatment should begin as soon as possible after exposure. It begins with a dose of rabies immune globulin given partially in the wound, if possible, and partially in the deltoid shoulder muscle. This is followed by a series of 5 vaccination injections given over 28 days.
A pre-exposure vaccine regimen consisting of 3 inoculations over 28 days is required for those working with laboratory bats. Completing the pre-exposure vaccine series does not eliminate the need for post-exposure treatment; it only reduces the post-exposure regimen.
The bats housed in the Moffett Animal Facility are from a pre-established laboratory colony held in captivity for two years without evidence of disease. This greatly reduces the likelihood that the bats carry rabies. Wild bat colonies being worked with and monitored at the Stony Ford location present greater risks that rabies might be present.
In the event of a bat bite or mucous membrane exposure to bat saliva, it is critical that the following be done:
1) Immediately wash the wound thoroughly with soap and water. Flush exposed mucous membranes of eye, nose, or mouth for 15 minutes at an eye wash station, sink drench hose, or hose from a potable water source.
2) Proceed to McCosh Health Center for medical evaluation and appropriate post-exposure treatment. (Contact number for McCosh Health Center is 258-3129).
HISTOPLASMOSIS
Histoplasmosis is a disease caused by the fungus Histoplasma capsulatum. The histoplasmosis fungus lives in soil, especially soil and material that is contaminated with and enriched by heavy accumulations of bat or bird droppings. Spores become airborne when contaminated soil is disturbed. Breathing the spores causes infection. The disease is not transmitted from an infected person to someone else.
Infection with histoplasmosis is common, but the disease is rare. Most infected persons have no apparent ill effects and infection clears on its own without treatment. As many as 80 percent of persons living in U.S. areas where the fungus is common have a positive skin test, meaning they have had the infection in the past. However, most of these people do not have a history of histoplasmosis symptoms. When people develop symptoms, it usually involves the lungs and is characterized by weakness, chills, fever, muscle aches, chest pains, and a dry cough. Chronic lung infections can resemble tuberculosis and may progress over months or years.
Infection can be prevented by using the following precautionary measures:
Before disturbing potentially-contaminated soil or debris, thoroughly mist-spray the material to control dispersion of dust and soil into the air. Wear protective, disposable coveralls, gloves and a dust mask.
Zoonoses
- Non-Human
Primates
A
number
of potentially
serious zoonoses
are associated
with non-human
primates. All
macaque monkeys
housed in
Princeton
University
facilities
must be considered
to be infected
with Herpes
Simian B
virus. Marmosets,
although
they do not
carry the
herpes B
virus, can
carry some
of the other
disease agents
discussed
here. The
strength
and unpredictability
of non-human
primates
also poses
a danger
to those
handling
them. It
is critical
that work
with non-human
primates
be done while
wearing the
appropriate
personal
protective
equipment
and with
the well-established,
safe protocols
and procedures.
Simean
(Monkey)
B Virus is
a
herpes
virus
of
Old
World
macaque
monkeys. Common macaque monkeys used at Princeton University include Cynomologous
and Rhesus monkeys. However, all macaques are capable of transmitting this
disease. In monkeys, this disease agent causes symptoms like human cold
sore virus including mouth ulcers during acute infection and long periods of
inactivity. Viral activity in the monkey commonly occurs with stress or other
disease/conditions. Otherwise, the monkeys appear completely healthy
while shedding large amounts of active
virus in the saliva.
When
humans are
infected,
the virus
produces
flu-like
symptoms
that can
lead to death
within 3-14
days. The
virus will
survive on
contaminated
equipment
and a few human cases have been documented after workers were scratched
by
soiled equipment. Fortunately, the virus is susceptible to killing with
bleach solutions
and other
disinfectants
used in the
lab.
EHS
and Employee
Health have
developed
a comprehensive
program for
monkey workers
at Princeton
University
that includes
the designation
of PPE required
for each functional area where monkeys and potentially-contaminated equipment
are handled and detailed procedures for medical response and follow-up
for
injuries associated with monkey care and use. You should be aware
that most of the monkeys that have been tested at Princeton University
have been
positive for B-virus infection indicating they have had previous exposure
to the virus and could be carriers. Therefore, it is critical that
you be familiar with and plan to follow all the established practices and
procedures before beginning work in the monkey laboratory.
TUBERCULOSIS
Tuberculosis is
caused by bacteria that can be given to and acquired from
monkeys. Tuberculosis is
transmitted via water droplets in
the air from
infected monkeys and humans. Humans can contract the disease
by unprotected exposure to infectious droplets generated by the handling
of dirty bedding,
the use of high-pressure water sprayers, the coughing of animals with
respiratory disease, or contaminated feces of animals with
intestinal disease. Likewise, Princeton University’s
resident monkey colony is susceptible to human tuberculosis
that can be transmitted from
infected workers.
The prevention
and control measures
in place involve semi-annual
TB testing of each Old-World
monkey and the use of
PPE that includes
respiratory
protection. All human workers in the primate laboratory are tested
by Employee Health annually for TB. Required PPE for
working with monkeys is listed on postings located in each
of the areas of monkey
activity, including
the
main colony, veterinary quarantine, surgery, and experimental
areas. You must be certain that you understand and follow these
posted requirements.
MEASLES
Healthy
monkeys are susceptible
to measles from
exposure to humans who are shedding the measles
virus.
The infection in monkeys is severe and produces
rash, fever, malaise, and progressive
respiratory distress. Initial studies have demonstrated
the potential for vaccination of monkeys with a
common measles vaccine used in dogs. However,
all monkey populations should be considered susceptible
until proven otherwise. At
Princeton, all personnel who have contact with monkeys
are required to have adequate vaccination. There
are currently no reliable diagnostic tests to indicate
measles infection in monkeys
DIARRHEAL DISEASE
Diarrheal infections associated with monkey contact are
from infectious bacteria like Salmonella, Shigella,
and Campylobacter that
commonly cause foodborne illness in humans. Monkeys have been found
to be common carriers of these illness bacteria which may cause illness
in humans who ingest contaminated materials. In humans, these bacteria
produce an acute intestinal illness which may be severe, but in most cases
is brief and self-limiting. In animals, the illness and discomfort
is much reduced compared to humans, and usually
goes unnoticed. You can prevent transmission by following strict hygiene
procedures and appropriate use of PPE. Frequent and thorough hand washing,
although too often overlooked by workers, is critical to physically remove bacterial
contamination and prevent ingestion exposure. Of
the PPE recommendations, the most important is wearing
gloves during all
procedures and properly disposing
of soiled gloves when work is completed.
Field studies involving
wild animal populations can expose workers to a number of additional
zoonoses
that may be naturally
endemic in some
wild species. For those doing field studies
involving birds, mice, and other wild species,
more careful consideration needs to be given
to conscientious use of PPE, good personal
hygiene, i.e. hand washing, and appropriate
training and application of good animal-handling
techniques
to minimize exposure to infection or injury.
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