Seroprevalence and Risk Factors of Anaplasma spp. in German Small Ruminant Flocks

SIMPLE SUMMARY: Anaplasma phagocytophilum and Anaplasma ovis, tick-borne pathogens with zoonotic potential, have been detected in small ruminants in Europe and North America in the past. These intracellular bacteria cause tick borne fever and ovine anaplasmosis, respectively. The most common clinical signs of infection are fever, lethargy and anaemia. To date, little is known about the distribution of these pathogens in sheep and goats from Germany. Therefore, 3178 serum samples of small ruminants from 71 farms distributed in five German federal states (Schleswig-Holstein, Lower Saxony, North Rhine-Westphalia, Baden-Wuerttemberg and Bavaria) were examined for IgG antibodies to Anaplasma species by a cELISA based on the MSP5 antigen. In 70 flocks, antibodies to Anaplasma spp. were detected in both sheep and goats. Furthermore, a risk factor analysis was carried out by means of a questionnaire answered by the farmers. Older animals and females were more likely to have antibodies to Anaplasma spp. Moreover, sheep had a higher probability of becoming seropositive than goats. Using flocks for landscape conservation and the presence of cats and dogs on the farm increased the risk of having more than 20% seropositive animals within the flock significantly. Since antibodies to Anaplasma spp. have been detected in almost all flocks (70/71), it can be assumed that Anaplasma spp. might be underdiagnosed in small ruminants from Germany. ABSTRACT: Knowledge about the distribution of Anaplasma spp. in small ruminants from Germany is limited. Therefore, serum samples were examined from 71 small ruminant flocks (2731 sheep, 447 goats) located in the five German federal states: Schleswig-Holstein (SH), Lower Saxony (LS), North Rhine-Westphalia (NRW), Baden-Wuerttemberg (BW) and Bavaria (BAV). Antibodies to Anaplasma spp. were determined by a cELISA based on the MSP5 antigen. A risk factor analysis at animal and flock level was also performed. Antibodies to Anaplasma spp. were detected in 70/71 flocks without significant difference in the intra-flock prevalence (IFP) between the federal states. The mean antibody levels from sheep were significantly lower in northern Germany (LS, SH) compared to west (NRW) and south Germany (BW, BAV). Sheep had a 2.5-fold higher risk of being seropositive than goats. Females and older animals (>2 years) were more likely to have antibodies to Anaplasma spp. in one third and one quarter of cases, respectively. Flocks used for landscape conservation had a five times higher risk of acquiring an IFP greater than 20%. Cats and dogs on the farms increased the probability for small ruminant flocks to have an IFP of above 20% 10-fold and 166-fold, respectively. Further studies are necessary to assess the impact of Anaplasma species on the health of small ruminants in Germany.