The prevalence of rickettsial and ehrlichial organisms in Amblyomma americanum ticks collected from Ohio and surrounding areas between 2000 and 2010

Abstract

The lone star tick, Amblyomma americanum, feeds upon a variety of hosts and is a known vector of several human pathogens. In Ohio, populations of A. americanum have been expanding their range and increasing in abundance and distribution, thereby elevating the public health concerns regarding bites from this species. We used a set of PCR assays to detect the presence of ehrlichial and rickettsial species in A. americanum ticks submitted to the Ohio Department of Health Zoonotic Disease Program over an 11-year period (2000–2010). We did not detect the presence of known pathogens Rickettsia rickettsii or Ehrlichia chaffeensis, but we did identify the presence of two other bacterial species: ‘Candidatus Rickettsia amblyommii’, and Ehrlichia sp. Panola Mountain. ‘Candidatus R. amblyommii’ was the most common species identified (30.2%), whereas the ehrlichiae was quite rare (0.6%). With growing evidence implicating both ‘Candidatus Rickettsia amblyommii’ and Ehrlichia sp. Panola Mountain in mild to moderate human disease, our results support the importance of continued monitoring of A. americanum ticks for the presence of potential pathogens.