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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 of 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.   

Zoonoses - Mice & Rats (top)


    Laboratory Mice:

    betadyneModern laboratory mice are bred and screened to exclude all 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 always cleanse any wound immediately with soap and water or antiseptic and seek medical consultation at Employee Health.

    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 could be infected with:

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 PPE and good personal hygiene.

Lymphocytic Choriomeningitis Virus (LCMV) 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 h always cleanse any wound immediately with soap and water or antiseptic and report all injuries to Employee Health.

    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 - Aquatics

Fish and Amphibians
Amphibians and fish can serve as a source of exposure to zoonotic agents.  Although little published information is available regarding transmission of diseases associated with laboratory fish and amphibian research, several organisms have been identified as potential concerns. Awareness of the hazards, particularly for those who may be immune-compromised, and good hygiene practices can reduce the risk of infection while handling fish and amphibians and their tank water in the animal laboratory.

Potential for Transmission
Pathogens associated with fish and amphibians are transmitted to humans through accidental ingestion of organisms found in fecal material or direct contact of these organisms with broken, abraded or chapped skin.   Persons who are immune-compromised, including those who have a medical condition or are taking medications that affect the immune system, such as steroids or chemotherapy, are at greater risk of developing disease after exposure to these pathogens

Zoonotic Agents of Concern
M. marinum, M. fortuitum,  M. zenopi, M. chelonae and M. abscessus are nontuberculosis mycobacterium species that affect amphibians and fish.   Infections in human are rare and occur primarily after exposure through direct contact of the bacteria with broken or abraded skin. 
After exposure, symptoms may appear in 7-14 days and can include dermatitis, nodules under the skin, lesions or skin loss.  The infection can spread to nearby lymph nodes and has caused arthritis and bone infections. The more serious forms of disease are seen in immune-compromised persons.

Aeromonas spp.
Aeromonas hydrophila  is a bacterium found worldwide in tropical fresh water fish and many amphibian species. In humans, exposure can cause gastroenteritis or localized skin infections.  Immune-compromised individuals are more likely to acquire infections.

Salmonella spp.
Amphibians typically shed salmonellae in feces, making the aquatic environment a possible source of transmission.  The amphibian host may shed the organism in the absence of clinical signs of illness.  Acute gastroenteritis may develop in humans within 6 to 72 hours of ingestion of the bacteria.   Clinical signs of salmonellosis consist of fever, nausea, diarrhea and abdominal pain.  Most persons recover within 2 to 4 days, however, persons with weakened immune systems are more likely than others to develop severe illness.  In the state of New Jersey, healthcare providers are required to report salmonellosis cases to the local health department within 24 hours of diagnosis.

Chlamydophila spp.
Several chlamydial agents have been associated with outbreaks in laboratory amphibian colonies, including Chlamydophila pneumonia and Chlamydophila psittaci.  Route of transmission to humans is through direct contact and possibly the respiratory route.   Humans may develop a mild febrile respiratory illness which can lead to more serious conditions such as bronchopneumonia.

Edwardsiella tarda has been isolated from healthy amphibians.  The bacteria causes gastroenteritis primarily in persons with weakened immune systems and is spread through accidental ingestion or direct contact with broken or wounded skin.

Zoonoses - Field Research

Field Research

Zoonotic disease concerns for field researchers varies considerably depending upon the animal species handled and the geographic location of the field research. Most, if not all, field researchers who are working with vertebrate animals should be familiar with the potential for transmission of rabies. Rabies vaccination will be offered by UHS to field researchers if indicated by the area of travel and the nature of the research.

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 prevented by 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.

Completing the pre-exposure vaccine series does not eliminate the need for post-exposure treatment; it only reduces the post-exposure regimen.

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 a potable water source.

2) Contact iSOS and request assistance with medical follow-up. The Medical Director or Attending Physician at University Health Services is notified of all calls to iSOS by Princeton students, faculty or staff.

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 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 well-established, safe protocols and procedures.
Herpes B

All researchers and husbandry staff who handle macaques, macaque body fluids and cell cultures derived from infected macaques or equipment that has come in contact with infected macaque body fluids, feces and urine must be familiar with precautions required to prevent transmission of herpes B virus.

  • All macaques are assumed to be capable of shedding Herpes B virus, even if they have no symptoms of the disease.
  • Humans have become infected after exposure to infectious tissues or fluids of monkeys. The ocular, oral, or genital secretions of monkeys, as well as the central nervous system tissues and cerebrospinal fluid of monkeys are potentially infectious. Primary cell cultures derived from macaque kidneys are a potential source of virus.
  • The virus is spread from macaques to humans through splashes of body fluid, such as saliva, conjunctival or genitourinary secretions to the eyes, nose and mouth; macaque bites and scratches; and broken skin contact with macaque body fluids or soiled equipment that has been in contact with macaques.   
  • Exposures can result in the transmission of the Herpes B virus which has a 70% mortality rate in humans if not treated immediately. Onset of disease can occur within 3 to 7 days and up to a month after exposure.  Early symptoms are flu-like and include fever, headache, and skin lesions at the site of exposure. Respiratory involvement and death can occur 1 day to 3 weeks after symptom onset.

Wear personal protective equipment.  Disposable lab coat, gloves, surgical mask, face shield or safety glasses, gown, booties and bonnet are required when working in macaque housing and procedures areas or when handling soiled equipment from these areas.
Long pants and closed toed shoes must be worn under protective equipment.
Hand washing can help prevent transmission of zoonotic organisms. Wash your hands with warm water and soap after removing gloves and upon exiting the animal facility or procedure rooms.
Disinfect equipment and surfaces that have been in contact with macaques and their body fluids.

Emergency Treatment of Exposures
The following exposures require immediate first aid and medical follow-up:

  • Macaque bites or scratches/abrasions from the macaque or the soiled cage
  • Punctures or lacerations by an instrument or needle contaminated by macaque secretions (saliva, secretions from mouth, mucous/genital membranes, conjunctiva)
  • Splashes in the mouth, nose or eye (mucous membranes) with macaque secretions, including feces and urine


  • Splash to eyes, nose or mouth: Irrigate exposed area with running water at an eyewash station or using a drench hose for 15 minutes.
  • Skin wound: Thoroughly wash injured area, using clean warm water and povidone-iodine impregnated brushes, available in monkey bite/scratch kits.  Wash for 15 to 20 minutes.


  • Employee Health: 609-258-5035
  • LAR Vet on-call: 609-258-0626
  • Your supervisor


  • Monday through Friday, 8:00 a.m. to 4:00 p.m.: Proceed to Employee Health, McCosh Health Center
  • After 4 p.m. and weekends:  You must proceed to the Emergency Room at University Medical Center at Princeton with the SOP and After Hours Protocol for Simian B Virus Exposure, from the Monkey Bite/Scratch Kit. 
  • Request transport from the Department of Public Safety if needed (258-3333).


  • Contact Employee Health (609-258-5035) the next business day regardless of whether you are faculty, staff, graduate student or undergraduate.
  • Principal Investigator/Supervisor must notify EHS Biosafety Officer

    Humans can spread diseases, such as measles (rubeola), tuberculosis and influenza, to marmosets.  Personnel who enter areas where marmosets are housed or tested must participate in the Medical Surveillance Program for Animal Workers, which includes proof of measles immunity and annual TB testing. 
    Although the use of personal protective equipment, proper disinfection and hand hygiene can reduce the potential for transmission of viruses, persons who have upper respiratory infections such as the common cold or flu or active herpes simplex lesions (cold sores) should not enter marmoset areas until symptoms have resolved.

    Mycobacterium spp. may be transmitted from humans to monkeys.  The bacteria can be spread through aerosolization of the organism, which can be found in the saliva.    All persons who enter monkey areas must participate in the Medical Surveillance Program for Animal Workers, which includes annual TB testing.  

    Rubeola (measles) can be spread easily from humans to monkeys.  A measles outbreak can devastate a marmoset colony.   The virus is extremely contagious and spreads via the airborne route.  All persons who enter areas where monkeys may be housed, tested or treated must have proof of rubeola immunity, which is included in the Medical Surveillance Program for Animal Workers.

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. 

Preventing Transmission of Zoonotioc Diseases

Wear Protective Clothing: The entrance to every animal area is labeled with the required protective clothing.

Hand washing is the most important measure you can take to prevent transmission of zoonotic organisms.  Wash your hands with warm water and soap after handling animals, soiled bedding or soiled cages.

Report injuries or illnesses to your supervisor and University Health Services.   Cleanse bite and scratch wounds immediately with soap and warm water.  Report animal bites and scratches, mucous membrane exposures and broken skin contact with contaminated equipment to University Health Services. 

Always tell your treating physician about your research.  Regardless of your symptoms, tell your physician about the work you do in the laboratory.  Persons with weakened immune systems should seek advice from University Health Services practitioners on risks associated with exposure to zoonotic agents in the animal laboratory.

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