#### State-of-the-art methodology

Parasitic and climatic data are closely linked - climate plays a fundamental role in biology and vector ecology while the epidemiology of vector-borne diseases follows on directly from that.

The idea of combining parasitic and climatic data gave rise to the Fleatickrisk project, which is a scientific collaboration between Merial and Climpact making an assessment of the distribution, activity and density of parasites possible.

The bioclimatic model, initiated in September 2006, has since been adjusted with the integration of land cover in to the model. As the activity of each parasite depends on the vegetation type, the computed activity fields are modulated by integration of a representative field of the biotope weight.

In addition, a field data collection network, based on control veterinary clinics, enables validation and optimization of the model in real time.

Biological data originates from (i) epidemiological surveys carried out in collaboration with Universities and Veterinary schools over several years, (ii) discussions with European experts in parasitology and vector-borne diseases, and (iii) bibliographic data.

Climate data originates from a meteorological model widely recognized and used by climatologists – the ECMWF (European Centre of Medium Range Forecast) High-Resolution model (http://www.ecmwf.int/en/forecasts/datasets/set-i#I-i-a_fc).

This model relies on climatic and biological data and the results are therefore probabilities which can be affected by inaccuracies and variations in data. Our objective is to continue to improve forecasts, through an analysis of the causes of error and to limit them as far as possible. As a model cannot integrate all parameters (including microenvironments and microclimates), the density and/or activity of the arthropod vectors therefore correspond to those in an area known to be favourable.

Local adjustment by the veterinary practitioner with a good knowledge of the area is essential.

#### Description of the meteorological model

This model forecasts two biological indices based on climatic data (temperature and humidity) and vegetation:

- The weekly
**activity index (activity map)**: forecast for the coming week, expressed between 0 and 100.
- The
**density index of the 6 last weeks cumulated (density map)**, expressed between 0 and 100.

Correlation between these 2 indices allows evaluation of the risk level for each of the targeted parasite in a given location.

These index maps are built from the ECWMF model (0.125° grid), a high spatial resolution model, allowing us to model the local effects of the climate (proximity to the sea, wind corridors etc.) with the inclusion of details of vegetation based on LANMAP in the calculation of the coefficient. At each point in time and at a given point on the grid, the meteorological model observes the climatic parameters and integrates the biotope, which thanks to biological matrix of parasites, helps us to estimate the activity of the arthropods studied.