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!
