They invite themselves on wooded paths and tall grass from sunny days: ticks, well -known vectors of serious illnesses, proliferate in summer. But a new sanitary alert reveals an unexpected risk, not linked to their bites … but to what we put on our plate.
We knew the danger of tick bites, feared to transmit Lyme disease in particular. But recently, a new scenario worries the health authorities: that of a serious neurological infection contracted not in the woods, but at the table. In question, the consumption of raw milk cheeses, contaminated indirectly by ticks. This mode of transmission, never observed in France until recently, is now at the origin of several confirmed cases of brain inflammation as confirmed The Parisian.
The phenomenon remains discreet, but is gaining ground. According to the National Health Security Agency (ANSES), around thirty cases are identified each year in France. One of the most striking episodes took place in the Ain in 2020, where 41 people had been infected after consuming cheeses from a contaminated goat. In this case, more than two -thirds of patients have developed severe neurological symptoms. The link with the tick -infested pasture area has been clearly established.
Tick encephalitis: a rare infection … but potentially serious
The disease in question is tick encephalitis, a viral infection of the central nervous system. Long considered confined to Eastern Europe or Russia, it is now very present on French territory. If all the virus carriers do not develop symptoms. 10 to 30 % have pseudo-grippal syndrome, and up to 40 % of symptomatic cases evolve towards neurological damage such as meningitis or encephalomyelitis. These severe forms can leave lasting, sometimes disabling consequences.
The general public is still poorly informed about this disease, unlike Lyme disease. However, certain dairy products based on raw milk – including goat cheeses or short -riding sheep, such as faisses or chevotins – are deemed particularly at risk. “Ticks can prick cows, goats or sheep and excrete virus in raw milk” reveals Pauline Kooh, project manager and scientist. And for the moment, no specific regulations are important to search for this virus in milk. A disturbing gap, when you know that tick encephalitis could be “Much more present in France than what we imagine”in the words of the microbiologist Pascale Frey-Klett.
Contaminated animals without visible symptoms
The major difficulty in prevention of this contamination lies in the discretion of the virus in animals. Goats, sheep or infected cows have no clinical sign. Result: it is almost impossible for breeders to detect the presence of the virus without targeted milk analyzes. At the INRAE of Champenoux (Meurthe-et-Moselle), the “Tiquotheque” Accumulates samples from all over France. In this research center, Pascale Frey-Klett and her team keep more than 80,000 tick specimens, dead or living, to better understand the pathogens they convey.
The storage and analysis of these samples make it possible to follow the geographic progression of pathogens, including the tick encephalitis virus. According to specialists, the Auvergne-Rhône-Alpes region is today the most concerned in France. It combines ideal conditions for ticks – wooded environments, abundant fauna – and a high density of outdoor goat. To limit propagation, ANSES recommends adopting simple but effective measures: to install fences to avoid contact between herds and wooded areas, where ticks are omnipresent, especially in spring and summer. But beyond agricultural practices, the development of more efficient detection tools has become a priority in the face of the evolution of the disease.