Presence of Anaplasma phagocytophilum Ecotype I in UK Ruminants and Associated Zoonotic Risk.

is the causative agent of tick-borne fever in sheep, pasture fever in cattle, and granulocytic anaplasmosis in humans. The increasing prevalence and transboundary spread of in livestock, ticks, and wildlife in the UK poses a potential zoonotic risk that has yet to be estimated. Several ecotypes of show variable zoonotic potential. To evaluate the possible risk associated with the transmission of from ruminants to humans, the ecotype was determined by sequencing the gene from 71 positive blood and tissue samples from UK ruminants. Thirty-four sequences were obtained, fourteen of which were identified in multiple samples. Of the 13 nucleotide polymorphisms identified through pairwise comparison, all corresponded to synonymous substitutions. The subsequent phylogenetic estimation of the relationship with other European/world isolates indicated that all the sequences clustered with other ecotype I sequences. The presence of ecotype I closely reflects that observed in ruminants in continental Europe and suggests a lower risk of zoonotic transmission from this reservoir.