The members of the genus Anaplasma are important tick-borne rickettsial bacteria of veterinary and public health significance. Domestic ruminants are important reservoir hosts for several Anaplasma species. In this study, the occurrence of Anaplasma spp. was investigated by PCR in domestic small ruminants from Gansu, northwestern China. The results showed a high prevalence of Anaplasma spp. (46.2%, 201/435) in sheep. The average infection rates were 5.7%, 24.4%, 28.0% and 18.2% for A. ovis, A. bovis, A. phagocytophilum and A. capra, respectively. Coinfection of different Anaplasma species occurred in 96 (22.1%) sheep. The infections of Anaplasma species in sheep were confirmed by sequencing of msp4, 16S rRNA and gltA genes. Sequence analysis revealed a novel A. capra genotype in sheep that was distinct from the isolates identified from patients in northeastern China. This study gives the first insight of presence of four distinct Anaplasma species with veterinary and medical significance in sheep in northwestern China.
