Borrelia burgdorferi and Anaplasma phagocytophilum in ticks and their equine hosts: A prospective clinical and diagnostic study of 47 horses following removal of a feeding tick

Abstract

A total of 47 horses were tested for infections with the zoonotic pathogens Borrelia burgdorferi and Anaplasma phagocytophilum after the removal of one or more attached ticks (n = 120), which were subsequently examined for the presence of these agents. All horses were examined at the time of tick removal and 6-12 weeks later; thirteen horses were examined again at 9-23 months. Serology was performed using an IFAT, an ELISA and a commercially available rapid test. Initially, 45% of horses were positive for B. burgdorferi antibodies and 23% tested positive for A. phagocytophilum; 15% of horses were seropositive for both pathogens. Although seven horses showed evidence of seroconversion to Borrelia, only 1/7 showed possibly associated clinical signs. Borrelia DNA was detected in 43% of the removed ticks, with a predominance of B. valaisiana. By contrast, A. phagocytophilum DNA was detected in only 1 tick.