Mice Infected With Brain-Altering Toxoplasma Parasite Lose Their Fear Of Cats [STUDY]
Mice infected with the parasite Toxoplasma gondii lose their fear of cats, the result of a brain condition which persists even after the parasite has left a mouse's body, according to a study published in PLoS ONE. The pathogen, which infects mammals and birds, causes toxoplasmosis, causing mice to not only flee cat odor, but be attracted to it.
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"Even when the parasite is cleared and it's no longer in the brains of the animals, some kind of permanent long-term behavior change has occurred, even though we don't know what the actual mechanism is," said Wendy Ingram, a graduate researcher at UC Berkeley and lead author of the study.
In Ingram's study, she and her colleagues tested how long Toxoplasma-infected mice avoided bobcat urine. Mice typically avoid bob urine for weeks after becoming infected with Toxoplasma. But in testing three common strains of Toxoplasma, Ingram and her team found that the mice actually avoided the bobcat urine for up to four months.
This matters because humans can become infected by Toxoplasma. The Centers for Disease Control and Prevention considers toxoplasmosis to be among the five "Neglected Parasitic Infections," diseases which the CDC has targeted for public health action. Though the CDC says that over 60 million million men, women and children in the United States carry Toxoplasma, only a few will ever show symptoms. The parasite can be contracted from eating contaminated, undercooked meat, especially pork, lamb and venison. It can also be contracted by swallowing the parasite following the cleaning of contaminated kitty litter boxes. (Though you probably don't need to be told, it's a good idea to thoroughly wash your hands after cleaning a kitty litter box.)
"They seem like normal mice," Ingram said of rodents with Toxoplasma. "It's a really subtle effect. . . . Humans should be studied, and there are things we could look for."
In a 2012 study of 45,000 women in Denmark, those infected with Toxoplasma were found to be 1.5 times as likely to attempt suicide. In pregnant women, toxoplasmosis can cause miscarriage.
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