Zoonotic diseases

Zoonoses are diseases and infections including viruses, bacteria, parasites and fungi that are transmitted between animals and people. Innumerable case reports and epidemiologic studies have documented the occupational health hazards of zoonotic diseases from laboratory animals or their tissues in the conduct of biomedical research, teaching and testing.

The medical consequences of these infections have been as diverse as the group of involved etiologies themselves, ranging from no outward symptoms to severe illness and death. Animals carrying these infections may appear healthy even while carrying and shedding these organisms.

Methods of transmission from animals to people (and vice-versa) include both direct and indirect contact involving contaminated respiratory secretions, saliva, blood and other tissues, urine and feces, among others. Penetrating bites, scratches, and splashes of contaminated materials to the face of animal workers are therefore important to prevent. Spread to human beings in this context can also be minimized by proper selection and use of personal protective equipment (gloves, gowns, masks, eye/face protection, etc.), by proper work practices, and where possible by implementation of engineering controls such as safety needles, physical barriers and ventilation systems exhausted away from the hazard source. Indirect contact with contaminated surfaces or research instruments including sharps and soiled caging are likewise highly important contamination sources. Many zoonotic diseases are vector-borne, where bites from contaminated ticks, mosquitos, sandflies, mites, fleas and other invertebrates are important mechanisms of transmission so prevention of insect bites through proper clothing and proper use of insect repellents is important where they are present. Consumption of contaminated food or beverages is also an extremely important source of exposure and one of the reasons why eating and drinking in or near animal use areas is not allowed.

Most animals maintained in the University’s laboratory animal facilities are obtained by commercial vendors that have successfully eliminated all or most zoonotic agents from their colonies and ongoing health screening programs verify their absence. However, the broad variety of University faculty research programs involve many species, captive and wild, around the world, each with their own actual or potential set of zoonotic diseases. Animal users should become informed about this topic, how to recognize infection, and where to seek evaluation and treatment as soon as possible.

Animal handlers are at increased risk for work-related allergies, most commonly to rodents and rabbits, and sensitized persons with ongoing uncontrolled exposures can sometimes experience asthma and even anaphylaxis on occasion. A risk assessment with respiratory protection requirements exists for identifying and limiting exposure to these allergens. This has been developed specifically for the University and core features of this hazard have been imbedded into the occupational health program for animal workers.

Below is a list of some of the most pertinent resources available to the research community:

• CDC National Center for Emerging and Zoonotic Infectious Diseases: Disease information, prevention, and program areas
• CDC: Zoonotic diseases
• The Center for Food Security & Public Health: Animal diseases
• University of California, Davis: Zoonosis information by species
• University of California, Davis: Zoonotic diseases and risk assessment
• "Zoonoses or Everything I Didn't Want to Know About Wildlife Diseases"