Opening the black box of Anaplasma phagocytophilum diversity: current situation and future perspectives.

Thibaud Dugat,Henri-Jean Boulouis,Renaud Maillard,Nadia Haddad,Anne-Claire Lagrée

doi:10.3389/fcimb.2015.00061

Abstract

Anaplasma phagocytophilum is a zoonotic obligate intracellular bacterium known to be transmitted by ticks belonging to the Ixodes persulcatus complex. This bacterium can infect several mammalian species, and is known to cause diseases with variable symptoms in many domestic animals. Specifically, it is the causative agent of tick-borne fever (TBF), a disease of important economic impact in European domestic ruminants, and human granulocytic anaplasmosis (HGA), an emerging zoonotic disease in Asia, USA and Europe. A. phagocytophilum epidemiological cycles are complex and involve different ecotypes, vectors, and mammalian host species. Moreover, the epidemiology of A. phagocytophilum infection differs greatly between Europe and the USA. These different epidemiological contexts are associated with considerable variations in bacterial strains. Until recently, few A. phagocytophilum molecular typing tools were available, generating difficulties in completely elucidating the epidemiological cycles of this bacterium. Over the last few years, many A. phagocytophilum typing techniques have been developed, permitting in-depth epidemiological exploration. Here, we review the current knowledge and future perspectives regarding A. phagocytophilum epidemiology and phylogeny, and then focus on the molecular typing tools available for studying A. phagocytophilum genetic diversity.

Highlights

Anaplasma phagocytophilum is a tick-borne intragranulocytic alpha-proteobacterium, transmitted by hard ticks of the Ixodes persulcatus complex
In Colorado, the high prevalence of A. phagocytophilum infection observed in deer mouse (Peromyscus maniculatus) and in mexican woodrat (Neotoma mexicana), have led some authors to conclude that these rodents are reservoir hosts for this pathogen
The 16S RNA locus is not a highly discriminatory marker, this study suggested that variants infecting I. hexagonus could infect I. ricinus, the epidemiological cycles involving these two vectors may be interconnected

Summary

Introduction

Anaplasma phagocytophilum is a tick-borne intragranulocytic alpha-proteobacterium, transmitted by hard ticks of the Ixodes persulcatus complex. Two studies reported that the variants obtained from sika deer in Japan are genetically distant from those infecting wild ruminants and other animal species in Asia, Europe and the USA (Kawahara et al, 2006; Masuzawa et al, 2011). In Colorado, the high prevalence of A. phagocytophilum infection observed in deer mouse (Peromyscus maniculatus) and in mexican woodrat (Neotoma mexicana), have led some authors to conclude that these rodents are reservoir hosts for this pathogen They suggested that these animals could be involved in an alternative epidemiological cycle, in which I. spinipalpis could be the vector (Zeidner et al, 2000). The authors used groEL sequences to demonstrate that birds and bird-fed ticks harbored specific A. phagocytophilum variants, suggesting that these animals could be involved in an independent avian epidemiological cycle (Jahfari et al, 2014). This dual role could contribute to the high number of OGA cases observed every year in some European countries

Conclusions

Findings

Conclusion