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“Zoonosis, Part II”

Dr. Lila Miller, DVM, ASPCA


Zoonosis, Part II

Zoonosis is the term used to describe diseases that can be passed from animals to humans and vice versa. This is the second part of a discussion on the subject. The following information is provided for both the general public and shelter workers to help avoid contracting a zoonotic disease.

For shelter workers, the following precautions should be taken to avoid zoonotic diseases.

  • Wear gloves when cleaning and disinfecting cages, food and water bowls, litter pans, etc.
    This is especially important if you have any open wounds on your hands and arms.
    Wash your hands after removing the gloves. There may have been a break in the gloves.
  • Seek prompt medical attention for any scratches, bites or wounds received on the job.
    • Use gloves and the proper equipment when handling dangerous animals to avoid injury.
    • Wash and disinfect any wounds received immediately, and seek professional attention.
    • Avoid self-treatment.
  • Wash hands using iodine based disinfectant soaps.
    • According to the CDC, in order to wash ones’ hands properly, hands should be lathered and rubbed together vigorously for at least 10 -15 seconds, and then rinsed thoroughly under a forceful stream of warm water.
  • Never clean cages in the kitchen or anywhere food is prepared or consumed.
  • Avoid eating food in areas where animals are housed or treated.
  • Avoid keeping food in the refrigerator with veterinary drugs like vaccines or laboratory samples. These are considered biohazards.
  • Avoid letting animals lick your face or wounds.
  • Use extreme care to avoid being bitten or scratched when handling fractious animals.
    • Call for assistance whenever necessary and learn how to use proper restraint equipment such as heavy gloves, nets, tranquilizers, etc.
  • Pregnant women should wear gloves or avoid cleaning litter boxes because of the risk of contracting Toxoplasmosis.
    • The risk is actually minimal and most cases of Toxoplasmosis are not transmitted to humans from cat feces, but from ingestion of contaminated or undercooked meat. Prompt daily cleaning of the litter box disposes of fecal material before it becomes infective. However, to be on the safe side, this duty should be assigned to others.
  • If you do become ill, let your physician know that you work with animals.
  • If you don’t know if a disease or condition is zoonotic or not, assume that it is and treat it accordingly. Wear gloves and masks, isolate the animal, wash hands, and DISINFECT, DISINFECT, DISINFECT!


For the public, the following precautions should be taken to recognize and avoid zoonotic diseases.

It is important to recognize the signs that an animal is sick.

  • Some signs are more obvious than others. Important symptoms of disease may include:
    • Changes in normal behavior, depression, pale gums, loss of appetite, dehydration, fever, vomiting, diarrhea, ocular and nasal discharges, reddened eyes, hair loss or reddened skin, shaking the head, coughing, sneezing, lethargy, straining to urinate or defecate, blood in the stool or urine, lumps or swellings, penile or vaginal discharges, neurological problems like star gazing, head tilt, head pressing, seizuring, etc.

Veterinary advice and care should be sought for animals exhibiting signs of illness.

  • If the animal is a stray with an unknown medical history, extra care should be taken to avoid being bitten or scratched, gloves should be worn and clothing worn during handling the animal should be laundered in hot water and soap with bleach added as a disinfectant.

It is important to understand that diseases are transmitted by a number of different types of organisms, and mechanisms. This knowledge can help us stay healthy.

  • Most diseases are caused by bacteria, parasites, protozoa, viruses, fungi (the causative agent of ringworm) or yeasts. Parasites can be worms, mosquitoes, fleas, tick, mites, lice, etc. Some organisms can survive in the environment for long periods of time, like roundworm eggs and larva that transmit the disease known as visceral larval migrans.
  • Many diseases are transmitted by the fecal-oral route or through breaks in the mucus membranes or skin. (The rabies virus is most commonly transmitted by a bite, but can also penetrate the skin through a wound.) The most commonly encountered diseases are spread by direct contact with infected tissues, aerosolized particles, contaminated feces, urine, saliva, other bodily secretions or discharges, or through contact with fomites. Fomites are objects that are contaminated with disease organisms, such as clothing, hands, or grooming utensils, for example. In shelters, fomites are one of the most common ways diseases are transmitted, and one of the most overlooked mechanisms. They are particularly dangerous when dealing with viruses or fungi that can survive in the environment for long periods of time and are resistant to routine disinfection techniques.

Seek prompt medical attention for any scratches, bites or wounds received by an animal, even your own pet.

Avoid letting animals lick your face or wounds.

If you do become ill and the diagnosis is not straightforward, let your physician know that you live with or handle animals.

The single most effective thing you can do to avoid contracting a disease from an animal or from the shelter environment is to:


In addition, make certain to wash your hands before handling any food or putting your hands in your mouth or up to your face and eyes.

  • As mentioned before, many diseases are spread through the oral route or by penetration through breaks in the skin or mucus membranes. This one simple step of hand washing will prevent the spread of most diseases by avoiding the route of infection. The use of hand sanitizers is also highly recommended, especially in situations where it is unrealistic to expect that people will wash their hands after every animal contact. Hand sanitizers are readily available at any drugstore. This is not foolproof, however, as some disease organisms can penetrate intact skin or are inhaled. (Inhalation is fairly rare).

© 2002 ASPCA

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