Feline Toxoplasmosis and Human Health

Toxoplasmosis is caused by a protozoon called Toxoplasma gondii. Most warm-blooded animals may be infected, although infection rarely causes disease. It’s importance in human health is when a previously unexposed woman is infected during pregnancy, the infection can damage the foetus.

What are the signs of toxoplasmosis in cats?

Most cats that are exposed to the organism by eating infected animals (usually rats or mice) quickly develop an immune response, which eliminates the organism.

Rarely, the immune response is not sufficient and the organism forms cysts in various parts of the body. The signs of disease depend on where this damage occurs and include eye problems, respiratory disease, diarrhoea, hepatitis (liver inflammation), and nervous signs.

How is toxoplasmosis diagnosed?

A blood sample can be taken but a positive antibody test does not tell us whether the cat had been exposed in the past and is no longer infected, or if it is now causing disease. Sometimes, 2 tests are taken to see if the level of antibodies is rising, indicating that there has been recent exposure and the cat is developing its immune response. This will only be useful at the beginning of the disease process.

In some cats infection still persists in the form of tiny cysts in body tissues, but does not cause any signs of disease. If this cat’s immune system is suppressed (such as infections with feline AIDS), the infection can become reactivated.

How is toxoplasmosis treated?

Treatment consists of antibiotics.

How does toxoplasmosis affect humans?

20-40% of the adult human population have been exposed to Toxoplasma organisms and have developed immunity to reinfection. If a woman has previously been exposed to the organism, there is no risk of transmission to a foetus if she becomes pregnant. The only risk occurs if exposure occurs during pregnancy in a woman who has not been previously exposed.

Prevention of toxoplasmosis infection in humans

  • Discourage pet cats from hunting. Since eating rodents infects cats, pet cats that do not hunt will not be exposed and do not pose a risk to their owners. Even if a cat does become exposed, it only sheds infective eggs in its faeces for about 10 days
  • Avoid eating and handling raw meat. Humans are more likely to be exposed to the organism by eating infected meat, usually sheep, pigs and kangaroos. Therefore avoiding infection involves cooking all meat thoroughly and washing hands and utensils after handling raw meat
  • Wear gloves when gardening and cleaning litter trays. Since humans can be infected by exposure to eggs shed by cats, use gloves when gardening, and when emptying cat litter trays. Trays can be disinfected with boiling water. Eggs need over 24 hours to become infectious after being passed in the faeces, so cleaning litter trays daily. Cover sandpits to prevent cats from using them as litter trays
– Last updated 16 November 2012
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