Cats responsible for the largest transmission of disease to humans (zoonosis)

Researchers from Limoges have just demonstrated that the evolution and spread of toxoplasmosis was linked to the domestication of the feline over the last millennia. This work provides information on the role of humans in the emergence of zoonoses, and they could contribute to the development of a vaccine.

Experience the Interceltic Festival:
The Interceltic Festival of Lorient 2022

Domestic cats accompany us, observe us, soften us… and they are often carriers of toxoplasmosis. It is a zoonosis, that is to say a disease transmissible from animals to humans. Most of the time, it does not have serious consequences, but it can be dangerous for people with weak immune defenses, or for future babies when a pregnant woman is affected.

This disease is caused by a parasite called Toxoplasma gondii. It is already well known, but its evolution and distribution over the centuries still had its dark side. In a study published in Nature Communications, researchers from the University of Limoges, members of the Epimact* team, today reveal that domestic cats are indeed the main vectors of the parasite over time and throughout the world.

To reach this conclusion, the researchers studied the evolution of the parasite genome in recent history, on all the same 40,000 years.

Concretely, Toxoplasma gondii is a parasite of Felidae. But strains suitable for domestic cats are different from those suitable for wild felids. However, the cat is the only feline to be in direct contact with humans. The researchers were thus able to draw a parallel between the spread of the parasite and the travels of domestic cats.

10,000 years ago, the Phoenicians and Egyptians began to adopt wild cats. These domestic cats will then accompany humans on their migrations to Africa, Asia and Europe, bringing their parasites with them.

From the 16th century, we move from the old to the new world: with cats supposed to hunt rats in their holds, trading ships bring toxoplasmosis from Europe to America. Lokman Galal, lead author of the study, explains what piqued his curiosity: “We had very close strains on both sides of the ocean, and those strains were all domestic strains.”

Beyond not worrying a little more when our cat gives us intimidating looks, this study may have concrete applications. Aurélien Mercier, co-author, details: “We see the impact of man in the emergence of a very important zoonosis. We understand its mechanism”. The researcher goes further: “The identified genes could be targets for a vaccine. And vaccinating cats could short-circuit transmission of the parasite.”

Cat owners suspected it, but the work carried out in Limoges confirms that this elusive animal has not yet revealed all its secrets…

*The Epimact team, Epidemiology of chronic diseases in the tropics, labeled Inserm and IRD, receives funding from the National Research Agency.

Leave a Comment