Food, Global Health 2 min

Meteorological maps to help predict tick activity

PRESS RELEASE - As part of the French National plan to combat Lyme disease and other tick-borne diseases, INRAE and VetAgro Sup, together with Anses, Boehringer Ingelheim and CIRAD, have analysed the risks associated with the tick Ixodes ricinus, the main vector of pathogens in France and Europe. For this study, the research team used data collected from seven tick observatories, located in different climates throughout mainland France, as well as meteorological and environmental data (vegetation, soil, etc.). Additional field observation campaigns were also carried out. Their results, published in Geospatial Health and Scientific Reports, have made it possible to develop both a map indicating the most favourable areas for Ixodes ricinus and a model for predicting high-risk periods according to the seasons and weather in France. This first map makes it possible to better assess the risk of human exposure to ticks, and thus, better target prevention campaigns in the different municipalities. In the future, the aim is to combine map and model to produce weather maps capable of predicting the risk of tick bites.

Published on 01 June 2022

illustration Meteorological maps to help predict tick activity
© Pixabay

Mapping areas prone to tick activity

In France, Ixodes ricinus is present throughout most of the country and is the main vector of tick-borne diseases such as Lyme disease. The activity and life cycle of ticks depend on many environmental factors such as climate (oceanic, Mediterranean, continental, etc.), altitude, land use (forests, meadows, urban areas, etc.) and the presence of hosts. A rating ranging from "unfavourable" to "very favourable" was assigned to each of these four factors, the presence of hosts being assessed according to the density of wild ungulates (data from the French Biodiversity Agency). The research team combined their knowledge of such factors using multi-criteria decision analysis, which they applied to geographic information systems in order to create a map that would indicate the most favourable habitats for Ixodes ricinus.

Carte de france des habitats d'Ixodes Ricinus
Rating map of areas prone to the tick Ixodes Ricinus activity in mainland France . © I. Lebert et al. Habitat suitability of Ixodes ricinus tick in France using multi-criteria analysis. Geospatial Health Vol. 17 n°1

To validate this approach, they compared the map’s predictions to field data obtained through nymph sampling campaigns carried out in France. The map confirms that the most favourable areas for ticks are in the centre, north-east and south-west parts of the country, while the least favourable habitats are the Mediterranean and high mountain regions. This map provides valuable information for regions and municipalities and will be useful to better target prevention campaigns against ticks.

A model to predict tick activity according to the weather

Tick activity is also determined by weather conditions, which have an impact on the risk of pathogen transmission, including those responsible for Lyme disease. To better understand and describe tick activity, researchers used data from a network of 7 sites in mainland France. Since 2014, monthly sampling campaigns have been organised in these observatories to estimate tick density, but also to measure meteorological (temperature, humidity, etc.) and environmental variables (altitude, land use, etc.). By consolidating the information from 631 sampling campaigns, they were able to develop a statistical model to estimate tick activity according to location, season, and meteorological variables. This model can explain most of the fluctuations previously observed in tick activity.

Together, the map and the model provide valuable information to identify regions and periods with high tick exposure risk in France. The objective is to be able to combine the two in order to produce maps of tick activity for metropolitan France, based on meteorological data.

REfErences

Isabelle Lebert, Séverine Bord, Christine Saint-Andrieux, Eva Cassar, Patrick Gasqui, Frédéric Beugnet, Karine Chalvet-Monfray, Sophie O. Vanwambeke, Gwenaël Vourc'h, Magalie René-Martellet. 2022. Habitat suitability map of Ixodes ricinus tick in France using multi-criteria analysis. Geospatial Health, Vol.17 n°1 (2022) DOI: https://doi.org/10.4081/gh.2022.1058  

Wongnak P, Bord S, Jacquot M, Agoulon A, Beugnet F, Bournez L, Cèbe N, Chevalier A, Cosson JF, Dambrine N, Hoch T, Huard F, Korboulewsky N, Lebert I, Madouasse A, Mårel A, Moutailler S, Plantard O, Pollet T, Poux V, René‑Martellet M, Vayssier‑Taussat M, Verheyden H, Vourc’h G, Chalvet‑Monfray K, 2022. Meteorological and climatic variables predict the phenology of Ixodes ricinus nymph activity in France, accounting for habitat heterogeneity. Scientific Reports 12, no 1: 7833. https://doi.org/10.1038/s41598-022-11479-z

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Isabelle Lebert INRAE scientistUMR EPIA

Magalie René-Martellet VetAgro Sup scientistUMR EPIA

Karine Chalvet-Monfray VetAgro Sup scientistUMR EPIA

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