Cats can sometimes be reservoirs of diseases that infect humans. Most viruses and organisms that cause illness are species specific, meaning they are specially adapted to the host they infect. When a disease is able to make the leap from a cat to a human, it is referred to as zoonotic. Zoonoses (\zoe-uh-noe-sees\) include the most well known of cat and dog diseases, Rabies. Thanks to mandated vaccination strategies, Rabies cases in domestic dogs and cats have been all but eliminated. Un-vaccinated strays are still at risk from the feral canine and feline populations that act as a reservoir for the virus. Other zoonotic diseases are less well known, but can be equally dangerous to infected people. Appropriate vaccination protocols, parasite screening, and preventive medicine are key to reducing exposures to these preventable diseases.
Cat scratch fever is another familiar zoonotic disease. It is caused by the Bartonella bacteria. Spread by bite wounds and scratches, kittens are more likely to be infected with Bartonella than adult cats. Cats do not exhibit symptoms with this infection, so, it is not possible to predict which bites and scratches may lead to cat scratch fever. The symptoms in humans include swollen lymph nodes, fever, and headache.
There are a few feline intestinal parasites that can infect humans. People can become infected by roundworms by accidental ingestion of contaminated soil. Children are especially at risk. Infection of people by roundworms is usually mild or undetected, but can cause permanent damage if it leads to ocular or visceral larval migrans. These conditions are caused by the larvae migrating through the eyes and organs. While rare, ocular larval migrans can lead to blindness. Pregnant women should especially avoid infection by Toxoplasma. This parasite is contracted by contact with used cat litter, raw meat, and contaminated garden soil and can cause spontaneous abortion of the fetus. Good hygiene practices and routine parasite screening of pets can reduce the risk of human parasitism.
Ringworm isn’t a worm at all. It is a fungal infection of the skin. While the fungus that causes ringworm in cats is somewhat species specific, it can cause rashes and itching on susceptible people. Avoid handling cats that exhibit symptoms of ringworm, it can be spread on clothing and bedding that the infected cat has contacted. Another cat skin parasite, Cheyletiella is a microscopic mange mite that can occasionally cause skin rashes on people.
Ticks are a common parasite that carry rickettsial organisms that can cause debilitating illness in people. While Lyme disease, Rocky Mountain Spotted Fever (RMSF), and Ehrlichia do not usually cause cats to become sick, people can be infected by exposure to the ticks that carry the diseases. These diseases can cause acute and chronic symptoms including fever, joint pain, bleeding, and anemia. It is possible to become infected by handling a tick that carries the organism even if it does not attach to the skin. There are safe monthly topical treatments that will keep your pet free of ticks. Always check yourself and your children for ticks after camping, hunting, and hiking trips.
Leptosporosis causes subclinical (silent) disease in cats. Primarily considered a dog disease, cats may be carriers of the bacteria and spread them to humans. Leptosporosis is passed in the urine of infected animals. The organism can live outside the host in soil and water for months in ideal conditions. In people, it causes kidney and other organ damage.
Immuno-compromised people like those with HIV, cancer patients, and the elderly are especially at risk for feline zoonoses. Children who have not learned proper hygiene are also susceptible. Parasite prevention, vaccination strategies, and wellness examinations can reduce the chance that our cats may become sources of human disease. Awareness and hygiene can reduce the risk of exposure from already infected pets.