Distribution of ticks, tick-borne pathogens and the associated local environmental factors including small mammals and livestock, in two French agricultural sites: the OSCAR database

Abstract

This paper reports a database on the distribution and densities of <i>I. ricinus</i> ticks - the most common tick species in French agricultural landscapes - and the prevalence of three tick-borne pathogens (<i>Anaplasma phagocytophilum</i>, <i>Borrelia</i> spp. and <i>Babesia</i> spp.) in two sites in north-western ("Zone Atelier Armorique": ZA site) and south-western ("Vallées et Coteaux de Gascogne": VG site) France. The distribution and density of ticks along a gradient of wooded habitats, as well as biotic variables, such as the presence and abundance of their principal domestic (livestock) and wild hosts (small mammals), were measured from forest cores and edges to more or less isolated hedges, all bordering meadows. Ticks, small mammals and information on local environmental conditions were collected along 90 transects in each of the two sites in spring and autumn 2012 and 2013 and in spring 2014, corresponding to the main periods of tick activity. Local environmental conditions were recorded along each tick and small mammal transect: habitat type, vegetation type and characteristics, slope and traces of livestock presence. Samples consisted of questing ticks collected on the vegetation (mainly <i>I. ricinus</i> nymphs), biopsies of captured small mammals and ticks fixed on small mammals. In the VG site, livestock occurrence and abundance were recorded each week along each tick transect.A total of 29004 questing ticks and 1230 small mammals were captured during the study across the two sites and over the five field campaigns. All questing nymphs (N = 12287) and questing adults (N = 646) were identified to species. Ticks from small mammals (N = 1359) were also identified to life stage. Questing nymphs (N = 4518 <i>I. ricinus</i>) and trapped small mammals (N = 908) were analysed for three pathogenic agents: <i>A. phagocytophilum</i>, <i>Borrelia</i> spp. and <i>Babesia</i> spp.In the VG site, the average prevalence in <i>I. ricinus</i> nymphs for <i>A. phagocytophilum</i>, <i>Borrelia</i> spp. and <i>Babesia</i> spp. were, respectively 1.9% [95% CI: 1.2-2.5], 2.5% [95% CI: 1.8-3.2] and 2.7% [95% CI: 2.0-3.4]. In small mammals, no <i>A. phagocytophilum</i> was detected, but the prevalence for <i>Borrelia</i> spp. was 4.2% [95% CI: 0.9-7.5]. On this site, there was no screening of small mammals for <i>Babesia</i> spp. In ZA site, the average prevalence in nymphs for <i>A. phagocytophilum</i>, <i>Borrelia</i> spp. and <i>Babesia</i> were, respectively 2.2% [95% CI: 1.6-2.7], 3.0% [95% CI: 2.3-3.6] and 3.1% [95% CI: 2.5-3.8]. In small mammals, the prevalence of <i>A. phagocytophilum</i> and <i>Borrelia</i> spp. were, respectively 6.9% [95% CI: 4.9-8.9] and 4.1% [95% CI: 2.7-5.9]. A single animal was found positive for <i>Babesia microti</i> at this site amongst the 597 tested.