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CAN YOU CATCH A DISEASE FROM YOUR CAT?
by Lorraine Shelton

    My introduction to zoonoses, diseases that can spread from animals to man, came in the form of an annoying upper respiratory infection that would not clear up. Many years ago I used to buy imported parrots from a quarantine station, bring them home, and tame them for sale as pets. I knew that this practice was slightly injurious to my health, as I sported bruises and scars from parrot bites so severe that a total stranger was prompted to give me the phone number of a battered women's shelter! But I didn't realize that these assaults to my flesh were not the only injuries I could sustain from my daily contact with pet birds.

    My doctor suspected that I had contracted psittacosis, a chlamydial infection of birds that can cause pneumonia in humans. Although easily cured in healthy young adults as myself with a course of antibiotics, this disease can be lifethreatening in immunocompromised persons, such as the very young and the elderly. After hearing this frightening news, I started to treat every incoming parrot for this disease as well as test them prior to sale to make sure I would not spread this disease to an unsuspecting pet owner.

    Since that time I have learned that it is important for my doctor to know my hobbies and my occupation so that he can be aware of diseases that other patients may not be at risk for. And I became aware of the potential for legal liability if one of my customers should become sick following the sale of one of my animals.

    Most zoonoses are very difficult to "catch". The organism that causes psittacosis is the same one that causes the very common chlamydial eye and respiratory infections in cats. However, the spread of this organism from cat to human is much rarer than from bird to human. However, in this day and age it is much more likely that one day we will place a pet into a home with an immunocompromised person. Lowering of the immune system by chemotherapy for cancer, prolonged use of steroids, or HIV infection increases the risk that a pet kitten may spread one of a variety of diseases to an unsuspecting new owner.

    Ringworm is probably the most common zoonosis of cats. It was quite common when I was working in the veterinary hospital to see a kitten come in covered in ringworm lesions, and to find that the owner was also vigorously scratching at suspicious-looking red scaly patches of skin! The ringworm fungus was cultured from 4-35% of asymptomatic cats at four different cat shows and studies of catteries suggest that as many as 40% of all cats may be asymptomatic carriers of ringworm. If you have EVER had ringworm in your cattery, chances are it will pop up again. I advise all cattery owners to inspect their kitten sales contracts carefully and consider putting in a warning about the possibility of ringworm infection. Otherwise, you may see yourself in court someday trying to defend yourself against a demand for reimbursement for the costs of medical treatment for a six year old and all the children in his first grade class. I have not yet heard of a situation where a cattery owner was held liable for severe fungal infection in an AIDS patient, but that is probably only a matter of time.

    Bacterial Infections can be spread from cats to humans. Bacteria are usually secondary infectious agents that follow viral or mycobacterial infections. Animals with diarrhea can be a source of infection to humans, as diarrhea more effectively contaminates the environment with pathogens than does a formed stool buried neatly in kitty litter. Most bacterial zoonoses (campylobacteriosis, streptococci, staphylococci) clear up readily with antibiotics. The most common bacterial zoonosis is the gram-negative organism Pasteurella. Approximately 60-75% of normal cats carry this bacteria in their mouths. Cat bite wounds should be cleaned carefully with antibiotic cleansers such as Nolvasan. An antibiotic ointment should be applied. Inflammation of the wound site or fever following a cat bite indicate that medical attention is required and systemic antibiotics may be indicated.

    Salmonella bacteria can be shed in cat stools and are more common in cats fed raw meat or those that catch wild birds. Hand washing following litterbox cleaning or handling of stools is effective in limiting spread to humans, as infection follows a fecal to oral route. Another gram negative bacteria causes tularemia infections. These are found in cats that catch wild rabbits or rodents and this bacteria may also be spread to humans. This, of course, is not a pathogen we need to worry about in our closed catteries.

    Cat Scratch Disease is one everyone has heard of, but only very recently has the causative agent been identified. The bacteria Rochalimaea henselae was cultured from over 40% of cats surveyed in a population of shelter cats. But more importantly to us as cattery owners, the organism was also found to be carried by cat FLEAS. The disease causes systemic illness and lymph node lesions and can be very serious in immunocompromised individuals. Antibiotic therapy usually cures the disease without complications in healthy young adults. Clearing the bacteria from infected cats requires long term antibiotic treatment, however, and cats may be continuously or intermittently infected indefinitely. Again, caution is urged following cat bites and scratches and the potential for the transmission of this bacteria should be another impetus to keeping the cattery free of fleas. Cat Scratch Disease is a fairly common disease with an incidence of about 0.8 cases per 100,000 population. Again, the risk of causing severe infections in immunocompromised pet owners needs to be considered.

    Parasitic Diseases are also potential zoonoses. Roundworm eggs can infect humans, particularly children, through a fecal to oral route. Tapeworm eggs, on the other hand, are not directly infectious to people. Feline strains of coccidia and giardia do not appear to be infectious to humans. Much media attention has been brought to the zoonotic potential of toxoplasmosis, a type of coccidia that can cause birth defects in unborn babies. However, poorly cooked meat is a much more significant source of infection than pet cats. Oocysts (eggs) must incubate for three days before becoming infectious to people, so regular litterbox sanitation and hand washing following this procedure is adequate to prevent exposure. Pregnant women may be advised to wear gloves when handling cat feces or, better yet, assign another family member to this job.

    Viruses are extremely species specific. Feline Immunodeficiency Virus, Feline Infectious Peritonitis, and Feline Leukemia Virus can not cause illness in people. A cat can not catch your "cold", although there is indication that canine coronavirus infection may potentiate FIP in cats.

    The purpose of this article is not to scare you into thinking that owning cats is hazardous to your health. But every hobby has associated risks, and your physician should be aware of the potential that the illness you have may be related to your hobby. I also want to caution breeders that when they are selling kittens, perhaps questions as to the presence of immunocompromised persons in the potential new home may be appropriate. In any case, a good sales contract should deal with the potential of zoonoses and offer you protection against being sued for large medical bills. I recently declined to sell a kitten into a home with an AIDS patient. It hurt me deeply, as I know the comfort that a pet can give, but I was not willing to risk that one of my kittens could cause severe illness in an immunocompromised person.

    Keeping a cattery clean, free of fleas, and feeding fresh cooked or processed foods can not only keep your cats healthier, but may also keep you healthier as well. Do not ignore cat scratches or bites and make sure your kitten customers are kept well informed so we can make sure that everyone's contact with these wonderful animals is as pleasant as possible!

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