Epidemiological study on Anaplasma phagocytophilum in cattle: Molecular prevalence and risk factors assessment in different ecological zones in Iran.

Anaplasma phagocytophilum is a tick-borne pathogen affecting humans and domestic animals worldwide. This study aimed to determine the molecular epidemiology and its associated risk factors of A. phagocytophilum infection in cattle in four ecological zones of Iran. A multi-stage stratified random sampling method was utilized during 2017-2018. A total of 1851 blood samples from 320 cattle farms were collected and examined using specific nested polymerase chain reaction (nPCR) based on the 16S rRNA gene. The overall prevalence of A. phagocytophilum was 15.5% (286/1851) by using nPCR. All four zones were A. phagocytophilum positive, the presence of A. phagocytophilum DNA was detected in eight out of nine tested provinces. Univariable analysis of risk factors indicated that climate, altitude, longitude, latitude, season, farm-type, feeding method, hygiene of the farm, tick infestation, use of acaricides by the farmer, distance from other farms, contact with wild animals, race, sex, and milk yield were significant determinants (P < 0.05) for A. phagocytophilum infection. The multivariable analysis determined that longitude, latitude, season, feeding method, and hygiene of the farm remained as significant risk factors for A. phagocytophilum infection (P < 0.05). Specific (SaTScan) cluster analysis identified two high risks and four low risks statistically significant clusters for A. phagocytophilum infection amongst the study areas (P < 0.001). Phylogenetic analysis indicated that A. phagocytophilum 16S rRNA isolates were 96-99% identical to sequences deposited in the GenBank. To the best of our knowledge, this is the first comprehensive molecular study on the epidemiology and risk factors analysis of A. phagocytophilum infection in cattle in different climatic zones of Iran. Further investigations are necessary to be performed regarding the tick vectors, reservoir animals, and the zoonotic potential of the A. phagocytophilum in the endemic region of Iran.