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The Occupational Health and Safety Program is designed to inform individuals who work with animals about potential zoonosis (disease of animals transmissible to humans), personal hygiene and other potential hazards associated with animal exposure. This information sheet is directed toward those involved in the care and use of laboratory rats and mice.
Colony-born rodents are generally docile, but may occasionally inflict injury such as a bite or scratch. While rodents may carry organisms that may be potentially infectious to humans, the major health risk to individuals working with rodents is the development of an allergy. The development of disease in the human host often requires a preexisting state that compromises the immune system. If you have an immune-compromising medical condition or you are taking medications that impair your immune system (steroids, immunosuppressive drugs, or chemotherapy) you are at higher risk for contracting a rat or mouse disease and should consult your physician. The following is a list of known and potential rat or mouse zoonosis.
Lymphocytic choriomeningitis (LCM) is an arenavirus commonly associated with hamsters, but does infect mice. LCM is rare in laboratory animal facilities, more common in wild. Tranmission to humans is through contact with tissues including tumor, feces, urine, or aerosolization of any one of these. Disease in humans is generally flu-like symptoms that range from mild to severe.
A bacterium found in many animals, including laboratory rodents. Leptospires are shed in the urine of infected animals. Direct contact with urine or tissues via skin abrasions contact with mucous membranes has been reported. Transmission can also occur through inhalation of infectious droplet aerosols by ingestion. Disease in humans is flu-like symptoms generally mild to severe.
Caused by the bit of a rat infected with Streptobacillus moniliformis or Spirillum minus. Rats may be asymptomatic carriers of these bacteria, which are considered normal flora in the oral pharynx of rats. Transmission is via the bite of an infected rat. Symptoms of disease in humans include fever, lymphadenopathy, swelling at the site of the wound, and may cause arthritis in untreated humans. Incubation period is generally 1-3 days but may be up to 6 weeks.
Hantavirus occurs among wild rodent populations in certain portions of the world. Rats and mice have been implicated in outbreaks of the disease. A Hantavirus infection from rats has occurred in laboratory animal facility workers. Rodents shed the virus in their respiratory secretions, saliva, urine and feces. Transmission to humans is via inhalation of infectious aerosols. The form of the disease that has been documented after laboratory-animal exposure is characterized by fever, headache, myalgia and petechiae and other hemmorhagic symptoms including anemia and gastrointestinal bleeding.
There are several other bacterial diseases that are possibly, though rarely spread through working with rodents. These include Yersinia, and Leptospirosis. Good handwashing and appropriate use of gloves are adequate measures to protect from these diseases.
By far the greatest occupational risk to working with rodents is allergic reaction or developing allergies. Those workers that have other allergies are at particular risk. Animal or animal products such as dander, hair, scales, fur, saliva, and body wastes, urine in particular contain powerful allergens that can cause both respiratory and skin disorders. Common symptoms of allergic reaction are nasal or eye symptoms, skin disorders and asthma.
