These researchers have created a weather map of ticks in France: a valuable tool

In mainland France, about 15% of ticks carry the Borrelia bacteria responsible for Lyme disease. That is why it is essential to remain very vigilant during your outdoor activities. to warn authorities, professionals and citizens, Magalie René-Martellet, Isabelle Lebert and Karine Chalvet-Monfra, members of the National Institute for Higher Education and Research in Food, Animal Health, Agricultural Sciences and the Environment, have published a first meteorological map of ticks in the area. Light on this precious tool.

Photo: 24K Production / Shutterstock

“We mainly offer a method”

The presence and abundance of ticks Ixodes ricinus, which is none other than the vector species of Lyme pathogens in France, is determined by several factors. Magalie René-Martellet, Isabelle Lebert and Karine Chalvet-Monfray have selected four of the most important and richest in data:

  • The climate : sign Ixodes ricinus does not tolerate dry environments well.
  • The nature of the soil : Ticks mainly develop in woodland and other vegetated environments favorable to humidity. Tight urban areas, airports, sandy surfaces or bare rocks are not conducive to their multiplication.
  • Presence and abundance of guest hosts : Ticks feed on a wide variety of hosts and the blood meal is essential for continuing their life cycle. Data from the French Bureau of Biodiversity (OFB) and the National Federation of Hunters have shown that the greater the number of ungulates (especially roe deer), the greater the risk of developing strong tick populations.
  • height : Several studies have shown that tick density decreases with height.

After these criteria were established, the researchers gave a score at each factor level depending on whether it is more or less favorable for the presence of ticks. The work of Magalie René-Martellet, Isabelle Lebert and Karine Chalvet-Monfray will “a method”as they explain to POSITIVR:

“In the future, this method could be used to create maps on a finer scale (department, municipality, provided we have reliable data at this scale) or even create future scenarios depending on climate change.”

But concretely, who is this first card intended for? “It is mainly intended until government policy to show that France is an area particularly conducive to the multiplication of Ixodes ricinus ticks, but also to help them target and target their vigilance messages in the areas most at risk for exposure.” But that’s not all, the map can also be useful for female researchers both professionals and citizens who have outdoor activities (walking, running, mushroom picking, etc.).

Map of habitats favorable to the tick Ixodes ricinus

This map shows that the vast majority of territory offers favorable conditions for character multiplication Ixodes ricinus with differences between regions, however. It should be noted that within less or moderately favorable zones, very favorable zones can be found that do not occur on this scale.

Dark green : unfavorable or unfavorable habitats.

From light green to orange : increasingly favorable habitats

Red : habitat very favorable for the tick Ixodes ricinus† This indicates that the 4 factors taken into account in this map (climate, land use, wild ungulate density, altitude) are each at a very favorable level for tick multiplication (example: non-Mediterranean climate, deciduous forest, high density of wild ungulates or altitude below 1,000 meters).

Note that the peak of tick activity Ixodes ricinus is generally in the spring with, in some areas, a second fall peak. However, Karine Chalvet-Monfray’s study has shown that the peak of activity can be shifted earlier or later in the season depending on the region. It should also be noted that in France there are other types of ticks that are also likely to transmit pathogens to humans (especially in the Mediterranean climate). The preventive measures are therefore essential throughout the territory during periods of tick activity.

What about global warming?

While it’s not always possible to distinguish between what’s due to global warming and what’s due to other environmental changes (such as variations in host plant abundance), the observations made by the researchers revealed , in a sense general, a drawing activity collapsed in late summer and a not negligible and increasing activity during winter in regions with a mild climate.

For Magalie René-Martellet, Isabelle Lebert and Karine Chalvet-Monfray, “this is fully consistent with the effect of climate change with warmer and drier summers, as well as milder winters

This card is therefore a valuable tool to protect yourself from these unwanted things. To continue, discover our testimony from Azel Revel, a young woman battling Lyme disease to be better recognized and cared for.

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