Seroprevalence of Anaplasma phagocytophilum, Ehrlichia spp. and Borrelia burgdorferi infections in horses: first report from Northern Bulgaria – Short communication

Abstract

Lyme borreliosis, granulocytic anaplasmosis and monocytic ehrlichiosis are well studied in humans and dogs. In horses, these diseases are not widely investigated and limited information is available about their occurrence. The purpose of this study was to present the first ELISA-based report on the seroprevalence of Anaplasma phagocytophilum, Ehrlichia spp. and Borrelia burgdorferi in horses from Northern Bulgaria. A total of 192 horses were investigated from three regions in Northern Bulgaria (Northwestern, North-Central and Northeastern Bulgaria). All equine sera were tested for A. phagocytophilum, Ehrlichia spp. and B. burgdorferi antibodies by a commercial rapid ELISA test. Antibodies against A. phagocytophilum were found in all the three regions at a mean frequency of 12% (23/192), ranging from 9.38 to 15.63% by region. Antibodies against Ehrlichia spp. were found in horses from one region (Northeastern) at a rate of 0.5% (1/192). Anti-B. burgdorferi antibodies were detected in all the three regions with a mean frequency of 15.1% (29/192), ranging from 14.06 to 17.19% by region. A co-exposure to A. phagocytophilum and B. burgdorferi was observed in 6.3% of the cases (12/192). This is the first report on the natural exposure of horses to these bacteria (A. phagocytophilum, Ehrlichia spp. and B. burgdorferi) in Northern Bulgaria.

Serological Evidence of Natural Exposure to Tick-Borne Pathogens in Horses, Romania

“…The seroprevalence of A. phagocytophilum (10.3%) in the present study is consistent with some serological surveys conducted in European countries, such as in northern Bulgaria (12.0%) [26] and France (13.5%) [21]. However, higher infection rates were reported in horses from Denmark (22.3%) [20] or southern Bulgaria (20.0%) [27].…”

“…The B. burgdorferi s.l. seroprevalence of 18.8% in our study is consistent with other European surveys, such as in Bulgaria (15.5%; 23.2%) [26,27], Sweden (16.8%) [38], and Germany (16.1%) [39]. Higher infection rates were reported for horses in Denmark (29.0%) [20], Poland (25.6%) [40], and Slovakia (47.8%) [41].…”

“…In Europe, two recent serologic studies from Bulgaria, a neighboring country, also reported the seroreactivity to Ehrlichia spp. in horses (seroprevalence values of 0.5% and 3.9%, respectively) [26,27]. In our study, one horse (0.5%) was seroreactive to Ehrlichia spp., and it was also positive for A. phagocytophilum and B. burgdorferi s.l.…”

“…Furthermore, 4.5%, 6.3-7.1%, and 11.0% of the examined horses in Sweden, Bulgaria, and Denmark, respectively, were seropositive for both B. burgdorferi s.l. and A. phagocytophilum [20,26,27,38]. The presence of dual infections is not surprising since both pathogens are vectored by I. ricinus ticks; however, coinfection with A. phagocytophilum and B. burgdorferi s.l.…”

The first serological evidence of Anaplasma phagocytophilum in horses in Slovakia

“…In Europe, a seropositivity higher than this was observed only in the Czech Republic (Praskova et al, 2011). In other European countries, seropositivity to A. phagocytophilum in horses has ranged between 16.7 and 22.75% until now (Egenvall et al, 2001;Leblond et al, 2005;Hansen et al, 2010;Passamonti et al, 2010;Ebani, 2019;Tsachev et al, 2019).…”