Seroprevalence of Antibodies Against Anaplasma spp. in Algerian Sheep and Associated Risk Factors

This study aimed to determine the seroprevalence and identify the main risk factors associated with exposure to Anaplasma spp. in sheep from two Algerian regions, Médéa and Bordj Bou Arréridj. Between March and November ۲۰۲۱, a total of ۳۶۱ blood samples were collected from sheep during both spring and autumn seasons. The sera were analyzed using a competitive enzyme-linked immunosorbent assay (MSP۵-cELISA), which detects antibodies against Anaplasma spp. but does not distinguish between species. The overall seroprevalence reached ۷۳.۱۳%, with a significantly higher rate observed in Médéa (۸۱.۰%) compared to Bordj Bou Arréridj (۷۰.۱۲%) (odds ratio [OR] = ۱.۸۲). Multivariate logistic regression analysis revealed that age (۱۲–۲۴ months), sampling season (spring), sub-humid climatic conditions, and tick infestation were significantly associated with Anaplasma spp. seropositivity. Among these, tick infestation emerged as the strongest predictor (adjusted OR = ۱۱.۹۸, p < ۰.۰۰۰۱). No significant associations were detected with sex or breeding system.These results demonstrate a high level of exposure to Anaplasma spp. among Algerian sheep and provide the first cELISA-based serological evidence for these regions. The findings underscore the role of environmental factors—particularly climatic conditions and vector presence—in shaping the epidemiological dynamics of anaplasmosis in small ruminants. As MSP۵-based serology detects antibodies rather than active infection, these data reflect historical exposure rather than current infection status. Future research should integrate molecular confirmation (PCR and sequencing) and longitudinal follow-up to identify circulating Anaplasma species, assess infection seasonality, and design effective, region-specific vector control strategies to mitigate the economic impact of ovine anaplasmosis in Algeria.

کلیدواژه ها:

Anaplasma spp ، Sheep ، cELISA ، risk factors ، Algeria