Molecular characterization of Anaplasma phagocytophilum infection in the cervids and feeding ticks from Lithuania

Abstract

Anaplasma phagocytophilum is a bacterial pathogen, which is a major cause of zoonotic disease, anaplasmosis. The main vectors of A. phagocytophilum are ticks of the Ixodes ricinus complex. A. phagocytophilum has a broad geographic distribution and a high degree of biological and clinical diversity. Epidemiological studies in multiple countries have shown that the prevalence of A. phagocytophilum highly depends on the density of ticks and their potential hosts such as the cervids, which are one of the main sources of nutrition for Ixodes ticks. In Lithuania, the cervids are important game animals but their contribution as reservoirs for A. phagocytophilum remains unknown. The objectives of the study were to investigate the prevalence of A. phagocytophilum infections in the cervids and feeding ticks and to characterize the A. phagocytophilum strains obtained from the cervids and ticks based on sequence analysis of msp4 gene. A total of 187 ticks were collected from 44 cervids (roe deer, red deer, and moose) harvested by professional hunters during the hunting seasons of 2010–2013 and 2016–2017 in Lithuania. Blood and spleen samples were collected from 29 animals (27 roe deer and two red deer). A. phagocytophilum DNA was identified in ten (37.04%) of the 27 roe deer. The overall prevalence of A. phagocytophilum in I. ricinus and D. reticulatus ticks was 39.3% (70/178) and 22.2% (2/9) respectively. The sequence analysis of the msp4 gene of A. phagocytophilum revealed nine different sequence types: five msp4 sequence types were detected in ticks and seven in roe deer.