Genetic variability of Anaplasma phagocytophilum and its implication in the ecology of anaplasmosis in Central Europe

Anaplasma phagocytophilum is the causative agent of granulocytic anaplasmosis of both medical and veterinary importance. In Europe, A. phagocytophilum is transmitted by the Ixodid ticks, mostly Ixodes ricinus. It is mantained in nature by specific assciation to the several vertebrate hosts. In order to understand the ecology of this pathogen in Central Europe we have analyzed and compared the genetic variability of different A. phagocytophilum strains from questing and feeding ticks collected from vegetation and different vertebrate hosts (roe deers, rodents, birds, sheeps, dogs), as well as blood and biological samples of some vertebrate hosts (rodents and birds), from several sites in two regions of Central Europe (Slovakia and Northern Italy). A. phagocytophilum was detected in questing and host feeding I. ricinus ticks from all studied sites, as well as from feeding I. trianguliceps on rodents and rodents’ ear and spleen biopsies. Prevalence of A. phagocytophilum in areas with rodents was much lower (1.1%, 0.6%) than in areas without rodents (6%). In areas where I. trianguliceps ticks were absent we did not detect A. phagocytophilum in rodents. Phylogenetic analyses of A. phagocytophilum positive samples have shown that A. phagocytophilum genotypes in questing I. ricinus and feeding I. ricinus from ungulates, birds and dogs were distinct from genotypes found in rodents and feeding I. trianguliceps. our study from Central Europe confirms that A. phagocytophilum strains have specific associations with two vectors and different reservoir hosts. unlike in the uSA, A. phagocytophilum genotypes that are associated with rodents are probably transmitted solely by I. trianguliceps ticks, therefore these strains may be not of risk for humans