Toxoplasmosis: How a cat parasite exploits immune cells to reach the brain

Date:  December 8, 2017

Source:  Stockholm University

Scientists have previously shown that a parasite from cats can infect people's brain and affect our behavior. Now, researchers at Stockholm University have discovered how the parasite takes control of our cells.

"We have decoded how the parasite takes control of immune cells, converting them into moving "zombies" which spread the parasite in the body," said Antonio Barragan, professor at Stockholm University and one of the authors of the new study.

The infection toxoplasmosis is caused by the parasite Toxoplasma gondii and is widely spread. It's estimated that 30-50 per cent of the global human population are carriers. Cats are the parasites' main host, but the infection is also spread among other animals, including humans. A series of studies have previously shown that the parasite affects the brain of infected rats so that they lose fear of cats and even become attracted to cats' smell, making them an easy prey. This is how the parasite is spread onward, by ensuring that the rat is eaten by a cat. Toxoplasmosis is life-threatening to people with impaired immune systems and to unborn fetuses, but causes only mild symptoms in healthy individuals. However, there are studies showing that mental illnesses such as schizophrenia, depression and anxiety disorder are more common in people who are carriers of Toxoplasma gondii. There are also studies indicating that the parasite may affect aggressive or risky behavior.

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