Study finds that the cat’s parasite makes mice less afraid, but not only cats

According to new research conducted this week, the relationship between a notorious parasite spread by cats and mice that it infects may be more complex than we thought. Suggests mice infected with Toxoplasma gondii Not only are they less afraid of cats, but they are softer in general.

Toxoplasma gondii, more clearly known as toxo, has gained a lot of attention for its creepy forms. The typical life cycle of the single-celled parasite begins in cats, which defecate undeveloped eggs that end up in water or soil. If all goes well, an unfortunate rodent swallows those eggs, which then mature enough to bury themselves in the cells of their new host, usually in muscle or brain tissue. Then they ripen even more in a form of resistant cyst. When a cat becomes infected by eating a rodent host, the parasites reach full adulthood, reproduce and begin the whole process again.

But toxo is not content to simply play a passive spectator in the game of life. When it infects a rodent host, the parasite can subtly influence the animal’s behavior so that it is less afraid of the cat’s urine, research has shown. The rodent is more likely to venture directly into the jaws of Plumpers the brindle.

While there is no shortage of parasites capable of mentally controlling their hosts, these examples have mainly involved smaller and less neurologically complex animals such as insects. And there is even some evidence that the toxin could also affect human minds. Humans are not natural hosts of the toxin, but the parasite can infect us and remain hidden in our bodies for long periods of time (however, we are more likely to contract it by eating undercooked pork instead of having a cat). At least some studies have suggested that people infected with toxo are more likely to be impulsive or develop mental illnesses such as schizophrenia.

The new study, published Tuesday in Cell Reports, does not really enter into the controversial debate about the effects of the toxin on human behavior, but questions the assumptions about how it affects mice.

Through a series of experiments with mice infected with toxo, the authors found evidence of many more behavioral changes than simply loving the cat’s urine. Infected mice, for example, were more eager to explore new environments or spend more time outdoors compared to control mice. And the mice touched with toxins were also more willing to sniff the urine of several animals without backing away from fear, from both predators and lynx and non-predators such as guinea pigs. In other words, mice not only became tolerant of cats, but were less anxious.

“For 20 years, T. gondii it has served as an example of a textbook for adaptive parasitic manipulation, mainly due to the specificity of this manipulation, “said study author Ivan Rodriguez, a researcher in neurogenetics at the University of Geneva in Switzerland, in a statement.” Now we show that the alteration of behavior not only affects the fear of feline predators, but that there are important changes in the brain of infected mice, which affect various behaviors and neuronal functions in general. “

Rodriguez and his team also found evidence that these changes are caused by inflammation in the brain, rather than any action taken directly by the parasite. That is potentially important, because it could mean the level of infection of an animal (that is, the amount of toxin cysts and where they are in the brain) will determine how affected they will be.

But the authors caution that their findings should not necessarily apply to human toxin infections. And even if people can be mentally affected by these parasites, it is almost certain that the effects are much less dramatic than what we see in mice.

“We hope that people understand that they will not get the” crazy cat syndrome “if they become infected with T. gondii“Study author Dominique Soldati-Favre, also a researcher at the University of Geneva, said in a statement. Although it seems that subtle behavioral changes may occur in humans, inflammation in the human brain could never reach the same level as laboratory infected mice. “

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