How a parasite infecting wolves turns them into pack leaders

The pathogen responsible for toxoplasmosis affects the behavior of these animals, a study has shown.

What if the infection of a parasite could change the behavior of animals? At least that is what has just been demonstrated by a study published at the end of November in Nature Communications Biology.

After using 26 years of behavioral, spatial and serological data on wolves in Yellowstone National Park, Wyoming, USA, the researchers were able to suggest that wolves infected with the parasite responsible for toxoplasmosis were more likely than others to become pack leaders.

Infection due to contact with cougars

You should know that wolves infected with toxoplasmosis are at the base through cougars.

But as infected wolves become less afraid than others, they then come into further contact with cougars and retransmit the parasite to the original hosts. The loop continues like this…

Toxoplasma gondii is a protozoan parasite capable of infecting all warm-blooded species and mainly felines (therefore cougars), but it can also be transmitted to wolves and humans.

A parasite that drives risky behavior

The results of published research show that infected wolves adopt a very young more risky behavior than their uninfected counterparts.

In fact, these infected wolves leave their pack earlier to try to find their own pack. Then they behave more aggressive, more dominantand explains that they become pack leaders more easily.

Hormonal changes?

The researchers explain that “experimental studies have shown that chronic infections, even in healthy individuals, can lead to increased production of dopamine and testosterone. These chormonal changes can lead to increased aggression and risky behavior such as increased hyperactive movements, inability to avoid olfactory cues from predators (i.e. seek out rather than avoid urine for Felidae) among others”.

Result infected wolves are notably more dominant, less fearful and more conquering in breeding.

Benefits for the parasite

The agent is thus transferred more easily by sexual means, as the wolves will conquer more distant territories, therefore the distribution is wider and since the animal takes greater risk it can die more easily and the parasite can thus infect animals that live on carcasses.

What about humans?

As specified by the National Health Security Agency (Anses), this infection is common in France. “About 50% of the adult population is infected usually without noticeable symptoms. It is estimated that 200,000 to 300,000 new infections occur each year. In healthy people, toxoplasmosis is usually mild. The severe forms are primarily seen in cases of infection of a mother during her pregnancy and secondary transmission to her fetus (congenital toxoplasmosis) and in immunocompromised patients.

But a curious study, published on PeerJ last March, ensures that infection with this parasite of humans also cause a change. And the man or woman who got toxoplasmosis would be, according to the researchers more sexually attractive and wanted more sexual partners… All this to allow the parasite to spread more easily in the population.

Although scientists remain cautious and encourage research on this topic to complete their postulate.

But at the end of the day, there may be some benefits to being infected with a pathogen a few times…

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