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

Abstract

Anaplasma phagocytophilum 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 A. phagocytophilum in livestock, ticks, and wildlife in the UK poses a potential zoonotic risk that has yet to be estimated. Several ecotypes of A. phagocytophilum show variable zoonotic potential. To evaluate the possible risk associated with the transmission of A. phagocytophilum from ruminants to humans, the ecotype was determined by sequencing the groEL gene from 71 positive blood and tissue samples from UK ruminants. Thirty-four groEL 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 groEL 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.

Molecular Detection of Candidatus Anaplasma camelii in Naturally Infected Dromedary Camels (Camelus dromedarius) in Abu Dhabi Emirate, United Arab Emirates, 2019–2023

“…Various Anaplasma species within the genus Anaplasma (denoted as A. ), such as A. marginale , A. centrale , A. ovis , A. bovis , A. platys , and A. phagocytophilum , have been reported to infect livestock, and some are zoonotic, as they can infect humans [ 11 , 12 , 13 ]. Anaplasmosis has a complex epidemiology due to its wide host range, the existence of different species of Anaplasma causing the disease, and vector transmission.…”

Anaplasma phagocytophilum Ecotype Analysis in Cattle from Great Britain

“…Transmission from mother to child immediately before or after birth has been documented in humans [ 14 ]; transmission to the foetus via placenta has also been reported in cattle [ 15 ]. Cases of canine, ovine, equine, bovine and human anaplasmosis have been reported globally and the infection of questing ticks, ruminants and wildlife has been reported in Europe over the past decade [ 16 , 17 , 18 , 19 , 20 ].…”

“…However, overall disease rates remain substantially lower in Europe than in the United States. The rarity of human infection with A. phagocytophilum in GB has been considered to be due to the absence of zoonotic isolates, also described as ecotypes [ 18 ]. Recent studies have documented A. phagocytophilum presence in GB, including a prevalence survey of questing ticks in Wales (12.1%), Northern England (4.7%), Southern England (1.8%) and central England (0.5%) [ 17 ].…”

“…Recent studies have documented A. phagocytophilum presence in GB, including a prevalence survey of questing ticks in Wales (12.1%), Northern England (4.7%), Southern England (1.8%) and central England (0.5%) [ 17 ]. Ecotype I has been recorded in GB sheep ( O. aries ) [ 18 ] associated with specific areas and is considered more likely to infect humans [ 17 ]. Gandy et al [ 17 ] and Bianchessi et al [ 18 ] examined questing ticks and sheep, respectively.…”

“…Ecotype I has been recorded in GB sheep ( O. aries ) [ 18 ] associated with specific areas and is considered more likely to infect humans [ 17 ]. Gandy et al [ 17 ] and Bianchessi et al [ 18 ] examined questing ticks and sheep, respectively. However, cases of bovine anaplasmosis [ 29 , 30 ] and co-infection with Babesia and A. phagocytophilum resulting in severe disease have been recorded in GB and Europe [ 16 , 31 , 32 ].…”