Epidemiological Study Related to the First Outbreak of Ovine Anaplasmosis in Spain

SIMPLE SUMMARY: Ovine anaplasmosis is an emerging disease in Europe, able to cause relevant economic losses. This disease has great significance in tropical and subtropical areas; however, climate change has facilitated the wider spread of ovine anaplasmosis throughout Europe during the last few decades. Related to the first ovine anaplasmosis outbreak that occurred in Spain in 2014, an epidemiological study was carried out in the affected area. The results show a high presence of Anaplasma ovis in the analysed flocks, indicating the high transmissibility of the bacteria. ABSTRACT: Ovine anaplasmosis is a vector-borne disease caused by Anaplasma ovis and mainly transmitted through tick bites. In Spain, the first outbreak of ovine anaplasmosis occurred in 2014. An epidemiological study in fifty-one farms was carried out associated with this outbreak in the affected geographical area. An epidemiological questionnaire was performed. In addition, whole blood samples were taken for molecular analysis in 47 of these farms to determine the prevalence of infection of Anaplasma ovis. A. ovis was present in 44 out of 47 PCR-analysed farms (93.6%). However, only 40.4% of the studied farms showed severe clinical signs. The clinical signs affected mainly young animals, which showed severe anaemia, weakness, anorexia, cachexia and epiphora. The early culling of young animals was more frequently reported by severely affected farms than the analysed farms without clinical signs (71.4% vs. 12.5%, p < 0.001). The geographical area where the farm is located seems to be relevant for the presence of clinical signs of the disease. Ovine anaplasmosis is an emerging disease in Europe that spreads rapidly through tick bites and is capable of causing significant economic losses when it spreads in a naive area and causes an epidemic.