Epidemiological study on the prevalence of Anaplasma ovis infection in Aragón, Spain

Ovine anaplasmosis is an emerging disease in Europe, primarily affecting the Mediterranean region. It is caused by Anaplasma ovis, a bacterium mainly transmitted by ticks. Despite its growing presence, comprehensive data on its distribution across Europe remain scarce. This epidemiological study aimed to assess the prevalence of A. ovis in sheep farms across Aragón, Spain, between March 2023 and April 2024. A total of 70 farms, covering a diverse range of climatic zones within Aragón, were sampled, representing 700 sheep. Two pooled blood samples, each comprising five sheep per farm, were tested using quantitative PCR (qPCR) to detect the presence of A. ovis. The results revealed a widespread presence of the bacterium, with 69 out of 70 farms testing positive. The only negative case was a farm located in a Steppe Dry climate area near Zaragoza, at approximately 240 m above sea level. Notably, no clinical signs of the disease were observed in any of the animals during the study period. In addition to the high prevalence, the study highlighted a concerning lack of awareness among farmers, with only 33 % reporting familiarity with the disease. These findings underscore the extensive distribution of A. ovis in Aragón and suggest that neither climatic conditions nor livestock management practices had a significant influence on transmission. The study also emphasizes the urgent need for enhanced control measures, increased farmer education, and further research into environmental and management factors that may contribute to outbreaks.