A new study shows feral cats living in places of high human population density tend to shed more of a parasite that causes toxoplasmosis, a disease that affects warm-blooded animals, including humans. 

Most studies around toxoplasmosis center around domestic cats, but this new analysis focuses on wild, stray, and feral cats. This study, from researchers at the University of California, also looks at the effects of temperature on parasite shedding. 

What is happening?

Toxoplasmosis is a disease caused by a parasite commonly found in feline feces. Cats ingest birds or small mammals infected with the parasite Toxoplasma gondii, and the parasite then reproduces in the cat's small intestine. The parasite creates oocysts, which are shedded in the cat's feces. 

The new study analyzed data from previous published studies on infected cats. The researchers were looking to see if human or climate-related factors had a noticeable effect on oocyst shedding.

While the researchers state that there is no proven causal relationship between human population density or temperature and oocyst shedding, they posit that rising human population and temperature changes may increase the likelihood of toxoplasmosis.

Why is this important?

If you've ever heard that a pregnant person should not scoop a cat's litter box, toxoplasmosis is why. Humans may get toxoplasmosis from touching infected cat feces or other contaminated material. 

Most people have mild symptoms if affected by toxoplasmosis, but in some cases, people may have severe symptoms that require medication or treatment.

The research suggests that changing climate or human behavior may increase the likelihood of toxoplasmosis shedding, which could "affect the risk of exposure to vulnerable people and wildlife."

In general, public health officials, veterinarians, and environmentalists agree that feral cats and free-roaming domestic cats can cause problems for local wildlife, as well as carry diseases like toxoplasma.

What is being done about toxoplasmosis?

The most important tool to combat toxoplasmosis is feral cat population control, since feral cats are more likely to have the parasite that causes toxoplasmosis. While most people are not severely harmed by this disease, at-risk populations may experience adverse effects.

Researchers stated that preventing cats from hunting may prevent infection, and this is best done by managing feral cats. Pet cats that don't roam are less likely to ingest infected materials, as it is most likely they are being fed cat food rather than wild vermin. Cat owners should reduce the time their cats spend outside unattended.

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