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In recent months, reports have been circulated that seem to indicate that toxoplasmosis can cause things such as brain tumors, schizophrenia and other brain-related illnesses. Further, these reports would seem to indicate that your pet cat could be a threat to you in terms of passing this disease to you. Let’s take a closer look at these assertions and see how true they really are.


What Is Toxoplasmosis?

Toxoplasmosis is a parasitic disease. It is caused by a protozoan (one-celled) parasite. The cat is the definitive host of the organism that causes toxoplasmosis, meaning that cats are required for the disease to continue. Cats are most commonly infected by ingesting contaminated soil or eating infected prey.

However, pet cats are not the most common source of human toxoplasmosis infections. In fact, you are more likely to become infected with toxoplasmosis through gardening activities or through eating improperly cooked meat or unwashed vegetables.

Toxoplasmosis is particularly dangerous for pregnant women, as the disease has the ability to damage the developing fetus. The disease is most dangerous when a woman is infected for the first time during her pregnancy. Toxoplasmosis is also a risk to individuals who are immunosuppressed, as are many other diseases.

Can Toxoplasmosis Cause Brain Tumors, Schizophrenia or Other Brain Diseases?

Maybe, maybe not. The truth is we really don’t have a definitive answer to that question at this point in time. There have been studies reported in the scientific literature that show a correlation between these conditions and being infected with toxoplasmosis. However, these studies fail to show a direct association between the two.

To date, no studies have demonstrated that toxoplasmosis is a direct cause of any of these diseases in people! Though associations have been made, these associations may well be coincidental and there may be many other correlations as yet unreported. The research on this topic is far from conclusive and much more research needs to be completed before we can reach any solid conclusions.

Furthermore, toxoplasmosis is a preventable disease. By taking some simple precautions, cat owners (and non-cat owners) can protect themselves against infection with this disease.

How to Prevent Infection with Toxoplasmosis

These simple steps can help protect you and your family from toxoplasmosis.


  • Cook all meats thoroughly before eating.
  • Wash all fruits and vegetables thoroughly before eating.
  • Wear gloves when gardening or working with soil.
  • Practice good hygiene, including washing your hands thoroughly and often. Always wash your hands before preparing food and before eating. Encourage children in your household to do the same.
  • Clean the litter box daily. Freshly deposited feces are not infectious even if contaminated with toxoplasmosis. It takes at least 48 hours for the organism to develop in the feces to the point where it can infect another animal or person.
  • Wear gloves when maintaining the litter box.
  • Do not dispose of soiled litter in gardens or other areas of your yard where you recreate.
  • If you are pregnant, consider asking someone else in the household to maintain the litter box.
  • Do not allow your cat to hunt. (Keeping your cat indoors is the easiest solution.)
  • Do not feed your cat raw meat. (Just like people, cats can get toxoplasmosis by eating uncooked meat.)
  • Follow a good parasite prevention program for your cat. Remember, toxoplasmosis is not the only parasite that is transmissible to people.


Above all, don’t panic and feel as though you need to get rid of your cat. Common sense, good sanitary practices and proper pet care should keep you and your family safe from toxoplasmosis.

Dr. Lorie Huston



Image: Garden Cat by play4smee / via Flickr

Comments  4

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  • Good Advice
    03/12/2012 06:53am

    It's amazing that people can so easily be convinced of old tales as seems to be in cases such as this. How did we ever survive past childhood without the internet?

    Keep Fluffy inside. Keep Fluffy's box clean. Wash your hands. That's all good advice whether one is afraid of toxo or not.

  • Toxo reproduces asexually
    03/12/2012 11:56am

    You state, "The cat is the definitive host of the organism that causes toxoplasmosis, meaning that cats are required for the disease to continue." It is true that felids are the definitive host; it is only in the gut of cats that T. gondii reproduces sexually. But the parasite reproduces asexually and vertically. Remove every feline from the face of the earth, and T. gondii persists. This "definitive host" argument has been used by conservationists to perpetuate the witch hunt of feral cats. Yet animals in areas where there are no cats (islands, northern Svalbard) have been found to be infected with T. gondii. Birds, rodents and ticks are all vectors for spreading the disease, and any carnivorous animal eating an infected animal perpetuates T. gondii in the environment.

  • 03/12/2012 03:42pm

    Thank you SaveSamoa, I appreciate hearing that they do reproduce asexually too!

    As for Toxo in cats, from my reading, it is very limiting..
    "Cats previously unexposed to T. gondii will usually begin shedding oocysts between three and 10 days after ingestion of infected tissue, and continue shedding for around 10 to 14 days,"
    "The presence of significant IgG antibodies to T. gondii in a healthy cat suggests that the cat has been previously infected and now is most likely immune and not excreting oocysts."
    from http://www.vet.cornell.edu/fhc/brochures/toxo.html

    so unless your cat was exposed recently and you don't scoop the litterbox regularly then to me it seems a non-issue.. not that I'm an expert or anything so I could be wrong.

  • Poop
    03/13/2012 10:39am

    I just wish people would teach their cats to use litter trays. I'm sick of my neighbours cats using my garden to do their bussiness whether they have toxoplasmosis or not. I pick my dog's mess up when I'm out and it annoys me when others don't. I mean we wouldn't go outdoors unless there was no other choice and I'm sure if we had to we would atleast cover it up, not just do it in the neighbours garden. Simple fact is there are many diseases that can be transferred by poop so clear up after all your pets.

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