Zoonotic diseases (also called Zoonosis) can pass from animals to humans. Although, most diseases are species specific. Most diseases pose no threat to humans and are treatable. Rabies while rare, is a dangerous disease and any zoonotic disease can pose a dangerous threat to those with poor immune systems.
This article’s purpose is to provide a short, simple guide to Zoonosis and is not all-inclusive and focuses on cat-related Zoonosis. Many people have had Zoonosis-related diseases and never realized it!
Ringworm is a fungus not a worm. Some Persian cats can be nonsystematic carriers (meaning it does not have any symptoms of Ringworm but sheds the spores and keep infecting other cats in the household or keeps giving it to owners). Nearly 40% of cats may have Ringworm without any symptoms. Vets who treat cats with Ringworm, are familiar with seeing owners with red, scaly, itchy patches of skin. Humans with Ringworm normally have circular scaly patches. To diagnose Ringworm in cats, a culture is done.
Proper treatment of Ringworm is essential to remove it from the household. Fungal spores can fly off the cat and land some distance away or get into the home’s ventilation system, on furniture, clothes, etc. Treatment for cats with Ringworm is with oral medication and dips or baths. Human treatment is usually by antifungal creams. When a cat owner gets Ringworm they often think it is eczema and seek treatment. As with other skin diseases, it may be itchy and continued scratching may cause scarring.
Secondary infectious agents often follow viral or bacterial infections. Bacteria may be present in diarrhea which results in cross-infection (solid stools buried in litter are less infectious). Common zoonotic bacteria respond well to antibiotics. Some cat breeders routinely dose their cats with antibiotics in an attempt to reduce disease in the cattery. However, the overuse of antibiotics leads to an increase in antibiotic-resistant strains of bacteria.
Various conditions can cause feline conjunctivitis (eye infection) including bacterial or viral infections. Conjunctivitis caused by a foreign body may lead to a secondary bacterial infection. Since some of these germs can also infect humans, it is wise to follow basic hygiene precautions when handling cats with conjunctivitis. Conjunctivitis is easily treatable in cats (and humans) with eye drops and eye ointments – often containing the same active ingredients.
Carefully clean cat bite wounds with antiseptic or antibiotic cleansers and apply an antibiotic ointment. Immediately see your veterinarian if there are signs of wound inflammation, persistent swelling or fever which may need antibiotics. Most healthy adults will recover without treatment; but you may not wish to risk your health.
Salmonella bacteria is more common in the feces of cats fed raw meat or those that catch wild birds. Infection follows a fecal-oral route (you clean the litter box and scratch your lip without first washing your hands).
Cat Scratch Disease (Cat Scratch Fever)
The bacteria, Bartonella henselae, causes cat scratch fever. It does not usually cause fever. Fleas carry the bacteria from cat to cat. Cat Scratch Disease causes systemic illness and lymph node lesions and can be serious in individuals with poor immune systems. Antibiotics usually cures the disease in healthy young adults. Long-term antibiotic treatment is necessary for sick cats. However, some cat suffer long-term infection no matter the treatment.
Cats pick up Toxoplasma infection by eating infected prey. In humans, Toxoplasmosis symptoms may be flu-like, usually there are no symptoms. Infection is more serious in individuals with poor immune systems. Pregnant women with Toxoplasmosis may have a baby with congenital issues.
Protect cats from infection by preventing access to birds, rodents, uncooked meat, and unpasteurized dairy products. Food preparation areas can be infectious to cats! Women who are pregnant (or trying to get pregnant) should avoid handling free-roaming cats to avoid contamination. This includes keeping indoor-outdoor cats off bedding, pillows and kitchen counters. Avoid cuddling a cat with diarrhea or bowel incontinence or one which has an illness.
Infected cats can transfer the tuberculosis causing mycobacteria to humans. It is dangerous to humans with poor immune systems. Since there is no effective treatment for cats to reduce the risk to humans, veterinarians recommend euthanasia for these cats. Tuberculosis is rare in cats.
Most viruses are species specific. Feline Immunodeficiency Virus (“FIV”), Feline Infectious Peritonitis (“FIP”), and Feline Leukemia Virus (“FeLV”) cannot cause illness in people. A cat cannot get the human common cold. There is indication that canine coronavirus may cause FIP in cats, and humans can infect cats with the flu virus. There are few feline viral infections which can cause illness in humans.
Diarrhea can occur in many species; however is usually temporary and treatable with medications. Rotaviruses can cross species; sick cats are not infectious to humans. However, when cleaning up diarrhea and disinfecting affected areas (litter boxes, floors, carpets), it is advisable to wear rubber gloves as a precaution.
Cats can transfer certain parasites to humans. Fleas are the most common and cause itchy, sometimes inflamed, spots. Some people are more prone to fleabites than others and some react worse than others. Humans may pick up a tick in long grass that has fallen off its former host. Ticks stay on cats until well-fed or until the owner or veterinarian removes it.
Transfer of some feline intestinal parasites to humans is possible. Roundworm eggs infect humans, particularly children, through a fecal to oral route. Tapeworm eggs are not directly infectious to people.
Good hygiene practices work for most Zoonosis. Disinfecting contaminated areas, washing hands after handling contaminated items (including cats and litter boxes) and wearing rubber gloves to prevent infectious matter entering skin wounds. Most Zoonosis results from cat to live prey contact, therefore, all cats should always stay indoors.