Summer sets in, we spend more and more time barefoot in the grass, lying on the lawn, sitting in the parks,… but watch out for tick bites. If today we know better about Lyme disease, which the bite of this small insect can cause, we know less about tick-borne encephalitis. Rarer, they still deserve attention. Explanations.
“Tick-borne encephalitis are viral diseases, transmitted (mainly) by the bite of ticks. Two virus subtypes can infect humans. They have a marked predilection for the nervous system”, introduces the Institut Pasteur. Both types are named after two regions:
- Eastern: this is the name of eastern tick-borne encephalitis which is located in the east of the former USSR. It is the most virulent form of the disease, described with a “severe neurological picture” by the Pasteur Institute and a high risk of mortality.
- Western: it is found in Western Europe, including France. It causes meningoencephalitis but with less serious effects and a “rather favorable” evolution notes the Institute.
Haute-Savoie and the Auvergne-Rhône Alpes region concentrate most cases
The disease is spreading in mainland France, new Public Health France : 71 cases were notified between May 2021 and May 2023. “86% of the cases were cases of “indigenous” infection (61 cases) and 14% (10 cases) had been infected in a country “at risk”, at the occasion of a trip or because it was their usual place of residence”, specifies the file. But France remains a country where it is rare, because each year there are between 5,000 and 13,000 cases worldwide. Eastern Europe, northern Japan and China are the places most at risk, underlines Vaccination info service.
Two places concentrate most of the cases in France: Haute-Savoie and more generally, the Auvergne-Rhône Alpes region. It is known that Forez is a place where many cases have been detected. The south of Ardèche and Alsace are also part of the sectors which have seen tick-borne encephalitis develop.
Tick-borne encephalitis: what are the symptoms?
Tick-borne encephalitis can be contracted in two ways. But one of them is much more common than the other. The first is the bite of ticks, most often in “wet wooded areas such as camping, hiking, mushroom picking” notes Public Health France. And the second, via raw milk or raw milk cheese, goat or sheep.
“Tick-borne encephalitis is an infection that affects the central nervous system (brain and spinal cord in a significant proportion of cases, and 40% of these cases can present neurological sequelae for several years”, describes Public Health France. 94% of people who contracted it were hospitalized.
According to Vaccination info service, the disease is often detected in the fall. “After one incubation one to two weeks, the disease begins suddenly like the flu, with fever, headaches and chills”.
How to protect yourself and react to tick-borne encephalitis?
To protect yourself, the most effective way is to avoid getting bitten. In high-risk areas, during forest walks for example, wear long clothes, tuck pants into socks and cover your head. Avoid tall grass and brush, use skin repellents. After a walk, examine your body and remove the tick with a special tool (or go to the pharmacy) if you find one.
There is also a vaccine, which is recommended for travelers who are expected to stay in rural or forested endemic areas up to 1500 meters above sea level. The areas concerned are: Germany in certain regions, Austria, Estonia, Finland, Latvia, Lithuania, Poland, Czech Republic, Western Russia, Slovakia, Slovenia, Sweden, Switzerland in certain regions.
Sources: Public Health France, Vaccination info service, Institut Pasteur
