Epidemiology and genetic diversity of Anaplasma ovis in goats in Corsica, France

Anaplasma ovisis a major cause of small ruminant anaplasmosis, a tick-borne diseasemainly affecting small ruminants in tropical and subtropical regions of the world. Due to health and production problems in dairy goat flocks in Corsica, France, and the demonstration of A. ovisinfection in some animals, an extensive survey was conducted in the island in spring 2016. The aim of the survey was to determine the prevalence and geographical distribution of A. ovisinfections in goats and ticks as well as possible relationships with anaemia and other health indicators. In addition, the genetic diversity of A. oviswas evaluated. Blood and faecal samples were collected in 55 clinically healthy flocks (10 goats per flock) for A. ovisqPCR, haematocrit determination, paratuberculosisELISA seropositivity and gastrointestinal nematode egg excretion quantification. Ticks were collected, identified and processed for A. ovisDNA detection. A high prevalence of A. ovisDNA detection was found at the individual (52.0%) and flock levels (83.6%) with a within-flock prevalence ranging between 0–100%. Rhipicephalusbursa was the only tick species collected on goats (n = 355) and the detection rate of A. ovisDNA in ticks was 20.3%. Anaplasma ovisDNA prevalence was higher in flocks located at an altitude above 168 m, in goats of Corsican/crossbred breed and in goats > 3 years-old. No relationship was found between A. ovisDNA detection at the individual or flock level and haematocrit, paratuberculosisseropositivity or gastrointestinal parasites. Positive A. ovisgoat samples were used for amplification of gltA and msp4 genes for species confirmation and strain identification, respectively. Sequence and phylogenetic analysis of these genes confirmed the detection of A. ovisand allowed identification of six different strains of this pathogen (named Corsica 1-6 (COR1-6). While the msp4 sequence of strain COR1 had 100% identity with strains previously reported, COR2 to 6 were found to be novel strains. The strain COR1 was the most represented, corresponding to 94.6% of the msp4 sequences obtained. The results showed a relatively high genetic diversity of A. ovisassociated with high bacterial prevalence in goats.