Ticks: why you should be wary of them this summer

If tick bites are possible in winter, then the summer period in France is the most dangerous season. From April to October, these small black insects, which prefer to hide in the undergrowth, tall grass, fields and wetlands, are especially active in their natural environment. If this is true for most of them, rather forest ones, then it should be noted that dry climate and hot periods are especially popular in hyalomma. Found so far mainly in shrubs or Mediterranean maquis, its presence tends to spread further with climate change.

For protection against bites, long clothing in the forest or in tall grass and vigilance are recommended. This is all the more true as, unlike for mosquitoes, there is no national monitoring system for these ticks, which nonetheless represent the most important vectors of pathogenic agents that cause serious illness in humans. Among them: the most common Lyme disease, as well as tick-borne encephalitis or Crimean-Congo hemorrhagic fever (CCHF).

This is the most common disease transmitted by ticks. And for good reason: according to a meta-analysis published at the end of 2022, which collected research on this issue, more than 14% of the world’s population became infected with Lyme borreliosis. Thanks to the bacteria of the complex Borrelia burgdorferi sensu lato, it is transmitted to humans by the bites of infected ticks.

Lyme disease is rarely fatal, but people bitten by an infected tick may develop some symptoms, sometimes late. The first skin, subsequent often flu-like, including muscle and joint pain, headaches, nausea and vomiting. If left untreated, in its most severe forms, it can lead to neurological disorders. Therefore, early diagnosis is important.

Less prevalent than Lyme disease in Europe, tick-borne encephalitis should not be ignored as it picks up pace, especially in France, where there have been 71 cases since 2021, according to a first report released earlier this month by Public Health France. In particular, 30 cases were detected in 2021, 36 in 2022, and 5 since the beginning of 2023, the health agency indicates. Most of them were men, with an average age of 48 years. But four children were affected, two of whom were under the age of 10, and five elderly people over 65 (age is an increased factor of severity).

Note that the department with the highest number of cases in these two years is Haute-Savoie. The Auvergne-Rhône-Alpes region now appears to be an important area for the circulation of the virus, with massifs such as Forez being particularly at risk. The south of the Ardèche also suffered. If the disease has “very low mortality” causes in symptomatic cases “significant consequences after damage to the central nervous system”said Alexandra Miles of Public Health France during a press conference.

Lee “no cases of infection of people with the Crimean-Congo fever virus have yet been observed,” The National Agency for Food, Environment and Occupational Health (ANSES) recently issued a warning of a potential risk based on an opinion and report on human and animal health risks from Hyalomma mites, which“Possible appearance in France.” Risk of occurrence of Crimean-Congo fever in France “the more likely that the geographical expansion of the area of ​​tick implantation should be facilitated by climate change”, according to Elsa Quillery, coordinator of scientific expertise, cited by ANSES.

A carrier of many pathogens, including the Crimean-Congo fever virus (CCHF), the Hyalomma tick is native to Africa and Asia. This mite, introduced mainly by migratory birds from Africa, has been present in Corsica for several decades, and on the Mediterranean coast since 2015. Thus, since 2013 in Spain there have been a dozen local cases of this fever among people, some of which led to the death of the patient, the agency notes.

If this fever is usually limited to flu syndrome with digestive disorders, “in some cases, it can worsen and lead to hemorrhagic syndrome, the mortality rate of which in some countries reaches 30%”.