Watching a fluffy kitten saunter by or an adult cat stretch out in the sun, and it is hard to resist the urge to reach out and stroke him. Softly stroking a feline triggers the release of oxytocin, the “love” chemical, and may be one of the big reasons we feel so drawn toward cats. Humans and felines have enjoyed each other’s company for centuries. Archeological evidence suggests that feline domestication dates back over 12,000 years to early civilizations in the Fertile Crescent. It is believed that cats became domesticated after the establishment of agrarian societies and the need for secure grain stores. The grain attracted mice, and cats were happy to help out. The cats were delighted by the abundance of prey in the storehouses; people were delighted by the pest control. In the United States, cats are the most popular house pet, with 90 million domesticated cats slinking around 34 percent of U.S. homes.

Cats may produce many benefits for humans, including lower incidents of cardiovascular problems, but they also increase the risk of miscarriage and schizophrenia. The reason cats increase the risk of miscarriage and schizophrenia is because the feces of cats contain toxoplasma gondii. T. gondii is an intracellular parasite that is known to selectively infect muscle and brain tissue in humans. Schizophrenia typically does not manifest until late adolescents or early adulthood, but the disease process has its origin in earlier brain development. Toxoplasma can cause long-term infections and increases retroviral activation. In some cases, schizophrenia may have a connection to toxoplasmosis, studies indicate that individuals with schizophrenia have higher prevalence of antibodies to T. gondii, some adults with acute toxoplasmosis have developed psychotic symptoms similar to schizophrenia, antipsychotic drugs are known to inhibit T. gondii, toxoplasma has been shown to elevate dopamine levels in animals (elevated dopamine is common in individuals with schizophrenia), individuals with schizophrenia may have greater exposure to cats in childhood. However, some studies have failed to find the connection between T. gondii and schizophrenia.

How can the risk of transmission of toxoplasma from a cat to its owner be reduced?

Although the risk of transmission of infection from a cat to its owner is very low, this can be reduced further and/or its consequences minimized by adopting the following recommendations:

1. People in ‘high risk’ groups should not have contact with the cat’s litter tray. Where possible, only non-pregnant and immunocompetent people (i.e. not those people with diseases or drug therapy suppressing their immune system) should handle cat litter trays (following all of the guidelines below).
2. Empty litter trays daily so that oocysts do not have sufficient time to sporulate (become infective) whilst in the litter tray.
3. Wear gloves when handling cat litter and wash hands thoroughly after cleaning the litter tray.
4. Use litter tray liners if possible and periodically clean the litter tray with detergent and scalding water (which kills oocysts) eg fill the litter tray with boiling water and leave for 5 – 10 minutes before emptying.
5. Dispose of cat litter safely. For example, seal it in a plastic bag before putting it with other household waste.
6. Cover children’s sandpits when not in use to prevent cats using them as litter trays.
7. Feed only properly cooked food or commercial cat food to your cat to avoid infection.
8. Washing hands after contact with a cat (especially before eating) is a sensible hygiene precaution.
9. If very concerned, ask your vet to check your cat’s Toxoplasma titre (antibody test for exposure to T gondii):
   a. Cats with a positive titre have been infected in the past and will not be a source of infection in the future as they have completed their period of oocyst shedding.
   b. Cats with a negative titre have not been infected with T gondii in the past and are likely to shed oocysts in their faeces for a short time if they become infected in the future. The risk of acquiring infection can be minimised by:
   • Avoiding feeding raw meat to the cat to reduce the risk of T gondii infection (see point 7 above).
   • Keeping the cat indoors to prevent hunting and access to intermediate hosts such as voles and mice

Amodeo, J. (2015, July 06). If You Love Cats, This May be Why. Retrieved January 16, 2018, from https://www.psychologytoday.com/blog/intimacy-path-toward-spirituality/201507/if-you-love-cats-may-be-why

Avoiding Childhood Exposure to Cats with the the T. Gondi parasite may reduce schizophrenia risk. (n.d.). Retrieved January 16, 2018, from http://www.schizophrenia.com/prevention/cats.html

Torrey, E. F., & Yolken, R. H. (2003, November). Toxoplasma gondii and Schizophrenia. Retrieved January 16, 2018, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035534/

Yolken, R. H., Dickerson, F. B., & Fuller, E. (2009, November). Toxoplasma and schizophrenia. Retrieved January 16, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/19825110

Zax, D. (2007, June 30). A Brief History of House Cats. Retrieved January 16, 2018, from https://www.smithsonianmag.com/history/a-brief-history-of-house-cats-158390681/