Multiple-locus variable-number tandem repeat analysis potentially reveals the existence of two groups of Anaplasma phagocytophilum circulating in cattle in France with different wild reservoirs.

Thibaud Dugat,Luc Véran,Céline Lesage,Gina Zanella,Nadia Haddad,Henri-Jean Boulouis,Guillaume Girault,Benoît Durand,Anne-Claire Lagrée

doi:10.1186/s13071-016-1888-4

Abstract

Background Anaplasma phagocytophilum is the causative agent of tick-borne fever, a disease with high economic impact for domestic ruminants in Europe. Epidemiological cycles of this species are complex, and involve different ecotypes circulating in various host species. To date, these epidemiological cycles are poorly understood, especially in Europe, as European reservoir hosts (i.e. vertebrate hosts enabling long-term maintenance of the bacterium in the ecosystem), of the bacterium have not yet been clearly identified. In this study, our objective was to explore the presence, the prevalence, and the genetic diversity of A. phagocytophilum in wild animals, in order to better understand their implications as reservoir hosts of this pathogen.MethodsThe spleens of 101 wild animals were collected from central France and tested for the presence of A. phagocytophilum DNA by msp2 qPCR. Positive samples were then typed by multi-locus variable-number tandem repeat (VNTR) analysis (MLVA), and compared to 179 previously typed A. phagocytophilum samples.Results Anaplasma phagocytophilum DNA was detected in 82/101 (81.2%) animals including 48/49 red deer (98%), 20/21 roe deer (95.2%), 13/29 wild boars (44.8%), and 1/1 red fox. MLVA enabled the discrimination of two A. phagocytophilum groups: group A contained the majority of A. phagocytophilum from red deer and two thirds of those from cattle, while group B included a human strain and variants from diverse animal species, i.e. sheep, dogs, a horse, the majority of variants from roe deer, and the remaining variants from cattle and red deer.ConclusionsOur results suggest that red deer and roe deer are promising A. phagocytophilum reservoir host candidates. Moreover, we also showed that A. phagocytophilum potentially circulates in at least two epidemiological cycles in French cattle. The first cycle may involve red deer as reservoir hosts and cattle as accidental hosts for Group A strains, whereas the second cycle could involve roe deer as reservoir hosts and at least domestic ruminants, dogs, horses, and humans as accidental hosts for Group B strains.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1888-4) contains supplementary material, which is available to authorized users.

Highlights

Anaplasma phagocytophilum is the causative agent of tick-borne fever, a disease with high economic impact for domestic ruminants in Europe
Detection of A. phagocytophilum DNA by msp2 qPCR In total, 82 of 101 animals (81.2%; 95% CI: 72.2–82.3%) were msp2 qPCR-positive: 48/49 red deer (98%; 95% CI: 89.9–99.1%), 20/21 roe deer (95.2%; CI: 76.2–99.9%), 13/29 wild boars (44.8%; 95% CI: 26.4–64.3%), 1/1 red fox, while the single river rat tested provided a negative result (Table 1, Additional file 1: Table S1)
This study is the first report of A. phagocytophilum DNA in a red fox and in wild boars in France

Summary

Introduction

Anaplasma phagocytophilum is the causative agent of tick-borne fever, a disease with high economic impact for domestic ruminants in Europe Epidemiological cycles of this species are complex, and involve different ecotypes circulating in various host species. Anaplasma phagocytophilum is a zoonotic intragranulocytic alpha-proteobacterium transmitted by ticks belonging to the genus Ixodes: I. ricinus in Europe, I. scapularis in Eastern USA, I. pacificus and I. spinipalpis in Western USA, and I. persulcatus in Asia and Russia [1]. It infects a large range of hosts worldwide, including humans, wild and domestic ruminants, horses, domestic carnivores, birds and rodents [1]. HGA appears to be rarer in Europe (even though the number of reported cases has increased during recent years, probably linked in part to improved surveillance [3, 4]), whereas a high number of TBF cases have been described in both cattle and sheep, causing significant economic losses [1]

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