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Health and Safety for Animal Workers




    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  Mice

    Laboratory Mice:

    betadyneModern 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 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.
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 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 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  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 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.


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 birdís 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


    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 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 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 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 Universityís 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.


    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 infections associated with monkey contact are from infectious bacteria like SalmonellaShigella, 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

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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