Free-roaming cats may spread potentially deadly parasite in urban areas, B.C. study suggests

Vancouver -

Cats that are allowed to roam free may be to blame for the spread of a potentially deadly parasite in urban areas, research conducted at a B.C. university suggests.

According to the study released by the University of British Columbia, wildlife living in dense urban areas were most likely to be infected with toxoplasma gondii, a parasite that causes disease linked to nervous system disorders, cancers and other debilitating chronic conditions.

"As increasing human densities are associated with increased densities of domestic cats, our study suggests that free-roaming domestic cats—whether pets or feral cats—are the most likely cause of these infections," said Dr. Amy Wilson, lead researcher and UBC faculty of forestry adjunct professor, in a news release.

"This finding is significant because by simply limiting free roaming of cats, we can reduce the impact of toxoplasma on wildlife."

According to the researchers, if a cat is infected, it can shed as many as 500 million toxoplasma eggs in about two weeks. Those eggs can live in soil and water for years, with the risk they might infect birds or mammals, including humans. Toxoplasmosis, the disease caused by the parasite, is especially dangerous for pregnant people, the researchers say.

Researchers say the parasite remains dormant if the animal carrying it is healthy. But if the animal's immune system is compromised, the parasite may cause illness or even death.

The study, which was recently published in Proceedings of the Royal Society B: Biological Sciences, also looks at how healthy ecosystems – like streams and forests – can help filter out these sorts of diseases. 

"There is a growing recognition among forest science professionals and other groups that protecting biodiversity and the ecosystems it supports is an efficient and economical approach to reducing disease transfer between wildlife, domestic animals and humans," Wilson said.

"Conservation is really preventative medicine in action."