Populated Cities More Likely to Have Wild Cats With Parasites

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June 23, 2023 – Reducing the population of feral, or wild cats, particularly in cities, may reduce the risk of people being infected with toxoplasmosis. This is a disease caused by a dangerous parasite carried by cats.

Researchers at the University of California, Davis, found that cats release more of the parasite, Toxoplasma gondii, when they live in areas that have higher human population density, such as cities.

Most previous research has focused on the risks of toxoplasmosis from cats who are kept as pets. Pregnant women are often instructed not to clean cat litter boxes because the parasite, which lives in cat poop, can pass from mother to an unborn baby. 

This latest study focused on feral cats and appeared this week in the journal PLOS One. Researchers analyzed data from 47 previously published studies and found 2.7% of feces samples were positive for the parasite.

Study authors suggested that the link between parasite levels and population density, which means more people live close together, could be due to “the release of unwanted pets, more outdoor pet cats, pet cats escaping, and proffered feeding to feral cat colonies.”

According to the USDA, there are 164 million cats in the U.S., of which 30 to 80 million are wild.

The Cleveland Clinic says most people don’t get symptoms from toxoplasmosis, but it is especially dangerous for people with weakened immune systems, leading to organ damage and possibly death.