First Molecular Survey and Genetic Characterization of Rickettsia spp. in Haemaphysalis hystricis Ticks Infesting Dogs in Taiwan

<i>Rickettsia</i> infection in <i>Haemaphysalis hystricis</i> ticks infesting dogs was first screened in Taiwan by nested-PCR assay targeting the citrate synthase gene (<i>gltA</i>) of <i>Rickettsia</i>. A general infection rate (3.46%) was detected in a total of 1186 examined ticks, and infection rates of 3.20%, 3.6%, and 4.27% were detected in females, males, and nymphs, respectively. The monthly prevalence of <i>Rickettsia</i> infection was observed from March to November, and the highest infection was detected in April (6.92%) followed by a higher infection in July (5.56%), October (4.72%), September (3.57%), and May (3.54%). The prevalence of <i>Rickettsia</i> infection in ticks infesting stray dogs (4.15%) is significantly higher than ticks infesting domestic dogs (1.11%) (chi-square test, <i>p</i> = 0.015). Genetic analysis based on the <i>gltA</i> gene sequences from 13 Taiwan specimens, compared with 13 genospecies of <i>Rickettsia</i> strains documented in GenBank, revealed that the genetic identities of these Taiwan strains were phylogenetically affiliated with the genospecies of the transitional group (<i>R. felis</i>) and the spotted fever group (<i>R. aeschlimannii</i> and <i>R. raoultii</i>) of <i>Rickettsia</i>. This study demonstrates the first molecular screening of <i>Rickettsia</i> spp. in <i>H. hystricis</i> ticks infesting dogs in Taiwan. The human pathogenic strain of <i>R. aeschlimannii</i> was first discovered in <i>H. hystricis</i> ticks infesting dogs. Because dogs serve as companion animals to humans, the presence of various <i>Rickettsia</i> species existing in <i>H. hystricis</i> ticks may pose a potential threat to human health in Taiwan.