A Trojan Horse: How Feline Toxoplasmosis Spread Around the World

In recent years, when we hear about toxoplasmosis, we inevitably associate it with cats. Although it can also manifest in other common pets like dogs, the preferred target of the parasite technically known as toxoplasma gondii is the feline. Humans can be reassured (we have enough to worry about with other viruses), because if we are infected, we probably won’t even notice it (more than half of the world’s population is thought to have developed antibodies against this virus) . In severe cases, it can cause quite serious illnesses such as psychosis or schizophrenia, but as a rule it is a parasite that mainly affects domestic animals.

It is said to be ” a zombie parasite“. This is explained by the fact that it easily penetrates the stomach of cats. First, it chooses mice and other rodents that cats tend to feed on as its host. It then seeps into their stomachs and intestines, reproducing through their droppings. Also, the waste products of these animals tend not to smell at all, which allows them to attract more prey and inhabit other bodies.

This is explained by Athena Aktipis, professor in the Department of Psychology at Arizona State University, who confirmed in an interview with Salon magazine that it is precisely by smell that rodents approach feline territory. , luring them into the trap of their prey. Everyone wins: the cat because it hunts more and the parasite because it reproduces in many more bodies.

It first targets immune cells to exist there secretly, infiltrating the rest of the body.

Humans, especially those who live with pets, are susceptible to infection, but there is no need to worry: as we said, in healthy people it rarely presents complications, although in people with weakened immune systems or in babies born to women who were infected during pregnancy, it can cause damage to the brain, lungs and other vital organs.

A Trojan horse

Scientists have recently discovered that the trick used by the toxoplasmosis parasite to survive and reproduce has made it one of nature’s most dominant life forms. Indeed, in the United States alone, over 60 million people have this tiny host in their destiny, making it king in the protozoan world. It uses “Trojan Horse” tactics, as scientists have dubbed it, by first targeting immune cells, its natural enemies, and then secretly settling there, infiltrating the rest of the body.

What has been most conducive to its rapid and widespread spread is the domestication of cats and the globalization of trade.

New research published in the scientific journal Cell Host & Microbe has shown that Toxoplasma gondii uses a protein called GRA28 to render itself undetectable by the body’s defense mechanisms and then “reprogram” the immune system. First, it attacks the phagocytes, the ” good » microbes that protect the body from foreign agents. More precisely, it acquires dendritic cells, which stick to it “behind” so as not to be recognized by the other cells, as if it were disguising itself so as not to be detected.

It is really surprising how this parasite manages to steal the identity of immune cells in such a clever way.“, says Antonio Barragan, lead author of the study, as reported by Salon. ” We believe these findings may explain why toxoplasmosis spreads so efficiently through the body when it infects humans and animals. »

Another study published in Nature Communications, which sequenced the parasite’s genome, found that it was the domestication of cats and the globalization of trade that were most conducive to its rapid and widespread spread. Ultimately, as with the pandemics that have plagued us for some time, it is amazing how the smaller biological agents take advantage of the social conditions of the times to thrive and get away with it.

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