Scientists discover parasites that make wolves bolder

Usually, one imagines that parasites adversely affect an organism’s health and well-being but there is more. Toxoplasma gondii parasite is known to influence the demeanour of an animal and for example it makes rodents less afraid of their predators.

Now as per a report in smithsonianmag.com, scientists have made a stunning find that grey wolves inhabiting Yellowstone National Park, United States, in whom T. gondii are active, have a greater chance of leading their pack than others.

Details of this new study, led by Connor Meyer and Kira Cassidy biologists of the Yellowstone Wolf Project, have been published in Communications Biology.

A single-celled parasite T. gondii is found in both human beings and animals for almost a lifetime. One in three human beings have it but people’s effective immune system doesn’t allow it to cause any sickness or disease according to Centres for Disease Control and Prevention.

Found at many places, this parasite can breed in the intestines of cats – both domesticated and wild. The CNN report states that the reason for this is the presence of an extra quantity of an acid that helps this parasite to reproduce. It spreads to other creatures when the affected being is eaten or when its faeces come in contact with healthy animals.

Scientists suggest that T. gondii persuades its host to take risks enabling it a better chance to find new hosts through contact. Studies done on them have demonstrated that rodents which have this parasite are not afraid of cat urine while captive chimpanzees playing host to it become fearless of leopard’s urine. Likewise, hyena cubs under its influence tend to get close to lions, whom they would otherwise avoid.

Talking to Science about this aspect of the parasite, Jaap de Roode, Emory University’s biologist observed: “These parasites are using some generic mind control or personality control that helps them fulfil their lifecycle.” He was not part of the study.

Researchers studied data collected on behaviour of wolves and their movement for 26 years in Yellowstone National Park. While the blood of some of these creatures was tested, many were monitored and tracked with the help of collars, trail cameras and planes.

Report of tests conducted on 229 wolves was scrutinised carefully and it was found that those infected by T. gondii were 11 times more likely to split from the pack to start a new group. They were also 46 times more likely to lead the pack than the unaffected ones.

Highlighting the crucial role played by the T. gondii, Connor Meyer, co-author of the study and wildlife ecologist at the University of Montana said: “We focus so much on vertebrate dynamics — wolves and elk, and how they affect each other — and for a long time, it seems like we have generally ignored the fact that parasites might play a role in those relationships. With something like Toxo, it seems like we should be giving parasites a little more credit.”

Commenting on the importance of the research, Meggan Craft, University of Minnesota’s wildlife disease ecologist said: “We know that infection can change animal behaviour, but it’s very hard to document that in wildlife populations. What’s cool about this study is that it leverages a fabulous long-term study to be able to tease apart these subtle impacts of infection and behaviour.”

The study also provided clues as to how wolves were infected by this parasite – those whose habitat was shared by cougars or the large cat native to the Americas – had a greater chance of contracting the parasite.