Wolves, emboldened by a parasite, often lead a pack – study



Wolves infected with a common parasite are much more likely to become leaders of their pack, according to a new study, suggesting that the brain-dwelling intruder encourages its owner to take more risks.

The single-celled parasite Toxoplasma gondii reproduces sexually only in cats, but can infect all warm-blooded animals.

An estimated 30 to 50 percent of people worldwide are infected with this parasite, which remains for life as dormant tissue cysts. However, people with healthy immune systems rarely have any symptoms.

While some studies report an association between having a parasite in the brain in humans and an increased risk, other studies dispute these findings and no definitive link has been proven.

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A new study, published Thursday in the journal Communications Biology, used 26 years of data on gray wolves living in Yellowstone National Park in the US to find out how the parasite might affect their behavior.

Researchers at the Yellowstone Wolf Project analyzed blood samples from nearly 230 wolves and 62 cougars known to spread the parasite.

Infected wolves are 11 times more likely to lead a pack

They found that infected wolves were more likely to penetrate deeper into cougar territory than uninfected wolves.

The study says that infected wolves are 11 times more likely to leave their pack than wolves without the parasite, indicating a higher level of risk.

The researchers calculated that an infected wolf is 46 times more likely to become the leader of the pack, adding that this role usually goes to the wolf. more aggressive animals.

Study co-author Kira Cassidy told AFP that while “being bolder isn’t necessarily a bad thing,” it could “reduce the survival of the bravest animals, as they may be more likely to make decisions that put them in danger.”

“Wolves don’t have room for survival to take much more risks than they already do.”

Cassidy said this is only the second study of the impact of T. gondii on wildlife, after last year’s study found that the increased boldness of infected hyena cubs makes them more likely to approach and kill lions in Kenya.

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Laboratory studies have also shown that parasitic rodents lose their instinctive fear of cats, driving them into the hands of a single host, where T. gondii can breed.

William Sullivan, a professor of pharmacology and toxicology at the Indiana University School of Medicine who has studied T. gondii for over 25 years, called wolfpaper a “rare treasure.”

However, he cautioned that such an observational study could not show a causal relationship.

“A wolf that likes to take risks might just be more likely to go into cougar territory and get infected with Toxoplasma,” he said.

But “if the results are correct, they suggest that we may be underestimating the impact of Toxoplasma on ecosystems around the world,” he added.

– What about the people? –

“That’s the million dollar question,” Sullivan said, adding that “no one knows for sure and the literature is mixed.”

Ajay Vyas, a T. gondii expert at Singapore’s Nanyang Technological University, cautioned against the conclusion that the infection could increase people’s propensity to take risks.

“Man’s behavior is very different from that of other animals,” he told AFP.

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People often become infected with T. gondii by eating undercooked meat or by domestic cats, especially when cleaning litter boxes.

In some cases, especially in people with weakened immune systems, T. gondii can lead to toxoplasmosis, a disease that can lead to damage to the brain and eyes.