Detection of novel strains genetically related to Anaplasma platys in Tunisian one-humped camels (Camelus dromedarius)

Introduction: Little information is currently available regarding the presence of Anaplasma species in North African dromedaries. To fill this gap in knowledge, the prevalence, risk factors, and genetic diversity of Anaplasma species were investigated in Tunisian dromedary camels. Methodology: A total of 226 camels from three different bioclimatic areas were sampled and tested for the presence of Anaplasma species by quantitative polymerase chain reaction (qPCR) and nested polymerase chain reaction (nPCR) assays. Detected Anaplasma strains were characterized by 16S rRNA sequence analysis. Results: Overall infection rate of Anaplasma spp. was 17.7%, and was significantly higher in females. Notably, A. marginale, A. centrale, A. bovis, and A. phagocytophilum were not detected. Animals were severely infested by three tick species belonging to the genus Hyalomma (H. dromedarii, H. impeltatum, and H. excavatum). Alignment, similarity comparison, and phylogenetic analysis of the 16S rRNA sequence variants obtained in this study suggest that Tunisian dromedaries are infected by more than one novel Anaplasma strain genetically related to A. platys. Conclusions: This study reports the presence of novel Anaplasma sp. strains genetically related to A. platys in dromedaries from various bioclimatic areas of Tunisia. Findings raise new concerns about the specificity of the direct and indirect diagnostic tests routinely used to detect different Anaplasma species in ruminants and provide useful molecular information to elucidate the evolutionary history of bacterial species related to A. platys.