Unit 16 -- Part 2 Public Health Concerns Zoonoses  
 

Definition: Stedman's Medical Dictionary defines zoonosis as an infection or infestation shared in nature by man and animals. Just as there are a number of different types of infectious agents responsible for animal diseases, there are a number of types of zoonoses. Below are the classes of zoonoses and examples of infectious agents within these classes.

1. Bacteria

Tuberculosis
Brucellosis (Undulant fever, Malta fever)
Plague
Leptospirosis
Listeriosis
Q fever

2. Viruses

"Equine" encephalidities (VEE, WEE, EEE)
Rabies
Morbillivirus (Australia)
Hanta virus

3. Parasites

Trichinosis
Visceral larval migrans
Cryptosporidiosis

(for another, very extensive list of zoonoses with lots of references, see Daniel Shapiro's Zoonosis Web Page.)

There are a number of ways to prevent zoonotic diseases from spreading to the human population.

One way of preventing humans from contracting zoonotic diseases is by distancing the human population from the animal source of the infectious agent. An example of this is use of rodent control to prevent homes from becoming infested with mice and rats that can carry a number of the agents, such as bubonic plague, leptospirosis and hanta virus.

A second means of preventing humans from contracting zoonotic diseases is by decreasing the prevalance of that disease in the animal population. An example of this is the animal eradication programs for TB and Brucellosis that have decreased the incidence of this disease in humans also. Vaccination of domestic dogs and cats has nearly eliminated the spread of rabies to humans in the United States. Knowing what specific zoonotic diseases could be carried by the animals with which you come in contact will allow you to "zero in" on the most likely agents.  Use of risk analysis is helpful in identifying disease agents and means of decreasing them or the exposure to them by animal workers.

A third means of preventing humans from contracting zoonotic diseases is by practicing good hygiene. Washing hands after handling animals, and wearing protective clothing (boots, coveralls, gloves, goggles and face masks) when handling animals known or suspected to carry zoonotic agents will minimize the chance of spread of the agents to their handlers.

Seeking prompt and accurate diagnosis of the cause of animal sickness and death is a necessary first step in recognizing and preventing the spread of zoonotic diseases!

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