Opinion – Reinaldo José Lopes: Toxoplasmosis parasite influences the behavior of wolves, who become pack leaders

Nothing gets me out of my head that the greatest ace in the world of parasites, the Pelé of creatures that make a living by manipulating larger and supposedly more complex forms of life, is a sly little fellow named toxoplasma gondii🇧🇷

Formed by a single cell, the cause of toxoplasmosis dominates two apparently contradictory strategies. On the one hand, he does everything to go unnoticed. As far as we know, this microorganism affects between a third and a half of the world’s human population, not to mention members of several other warm-blooded species. However, it is very rare that it causes any more serious health problems in its victims — real risks only appear when it infects pregnant women, young children or people with weakened immune (defence) systems for other reasons, such as AIDS.

However, evidence obtained mainly from other mammals indicates that the T. gondii is an expert in brainwashing, installing himself in the hosts’ nervous systems. After all, what else could explain the fact that rodents that carry it in their organism lose the deep fear they normally feel when sniffing cat pee? Similar things have already been verified in other animals – the microbe is capable of producing a totally unnatural fearlessness in its victims.

How come? Well, it turns out that, despite being able to infect all species, the T. gondii it has far more specific needs when it comes time to reproduce sexually (although it can also propagate asexually). As one researcher who will remain anonymous put it, all Toxoplasma wants is to have sex in a cat’s guts.

Or any other feline, for all we know. Sexual reproduction in the digestive system of these predators is an essential step in their life cycle. It explains, therefore, why he makes rodents lose their fear of cats: it is for them to be eaten — and transmitted to the kittens.

The latest chapter in this story is even more bizarre. Researchers in the USA, led by Connor Meyer, from the University of Montana, have shown that not even the wolves of the famous Yellowstone National Park escape the mind-control tricks of the T. gondii🇧🇷 In the park’s wolf packs, individuals who carry the parasite in their system are by far the most likely to leave their home pack and the most likely to become pack leaders.

The data, which have just been published in the specialized journal Communications Biology, are the result of monitoring that has lasted nearly two decades. The team identified the presence or absence of antibodies generated by the T. gondii in the organism of more than 200 wolves in the park. Everything indicates that the animals are being infected through direct or indirect contact with the puma (Puma concolor) that inhabit Yellowstone — felines, therefore, and preferred hosts of the parasite. In fact, wolves that occupy territories that are also frequented by pumas are more likely to carry the T. gondii in your body.

It’s hard not to wonder whether a manipulator as insidious as this one might be having similar effects on humans. Evidence for this is still sparse, although some researchers speculate that certain mental health problems could be associated with the infection. While the answers do not come, it is worth learning from the wolves: never underestimate the powers of a microscopic parasite.