Abstract
BACKGROUND: In Europe, Ixodes ticks are major vectors for both human and livestock pathogens, with the most widespread species, Ixodesricinus, being responsible for the transmission of the pathogenic agent of Lyme disease, Borreliaburgdorferi sensu lato. The disease is endemic in France, where the number of new human cases per year was estimated at 39,052 in 2023. I.ricinus is widely distributed in France, particularly in Auvergne-Rhône-Alpes, where its abundance is not always well known. Often, estimation of questing tick abundance is based on a single observation from several sites; moreover, depending on sampling conditions, the efficiency of sampling with cloth dragging is variable, but is generally low. Even when standardised protocols are used, abundance indicators and sampling rates are influenced by various factors including population dynamics, ground vegetation, soil layers and meteorology. One approach that can be employed to account for the impact of these factors on variations in sampling rate is the use of removal samplings, i.e. several successive samplings. NEW INFORMATION: The TELETIQ project (https://teletiq.clermont.hub.inrae.fr/) was interested in mobile phone and participatory science data for the estimation and understanding of the risk of transmission of environmental diseases with an application to diseases transmitted by ticks. It aimed to explore how data from information and communication technologies can be used to improve the estimation and understanding of the risk of transmission of diseases related to the environment. As part of this project, questing ticks were sampled in the field in 15 sites located in the Auvergne-Rhône-Alpes Region (France). We designed an innovative protocol that combined three months of sampling (to include the time of peak tick activity), two transects for each site (to increase statistical power) and the removal sampling method (to take account of the variation in the sampling rate due to ground vegetation). A sampling protocol was designed to collect ticks using the cloth-dragging method. In each site, sampling was conducted along two transects, with ten sub-transects (ST) per transect. Each sub-transect was subjected to three successive rounds of sampling per month, from April to June, 2018. Based on this, we created a dataset of questing tick abundance and information on local environmental conditions. Over the three months of sampling, 2,274 questing ticks were captured across the 15 sites. This total included 2,205 questing nymphs, 30 questing adult females and 39 questing adult males. I.ricinus represented 100% of the identified ticks. Of the 2,205 nymphs sampled over the three months from April to June 2018, 62% were sampled (n = 1,367) in the first round of sampling, 24.5% (n = 540) in the second and 13.5% (n = 298) in the third. In 29.7% of STs (n = 267/900), no nymphs were collected in any of the three successive rounds of sampling confirming a strong presumption of absence. In 57.9% of STs (n = 521/900), at least one nymph was collected in the first round of sampling. In 112 of the remaining STs - in which no nymphs were detected in the first round of sampling - successive sampling did reveal the presence of nymphs (12.4% of the 900 total STs, 168 nymphs collected overall, representing 7.62% of the total number of nymphs collected in this project). Without a removal sampling design, that is, with only a single sampling occasion, these STs would have been considered tick-free. The information in this dataset on the local abundance of questing I.ricinus ticks can be used to determine the best way to collect data in the field, based on the sampling rate and vegetation type.