Find in Library

Rickettsiae of the spotted fever group (SFG) are zoonotic tick-borne pathogens. Small mammals are important hosts for the immature life stages of two of the most common tick species in Europe, <i>Ixodes ricinus</i> and <i>Dermacentor reticulatus</i>. These hosts and vectors can be found in diverse habitats with different vegetation types like grasslands and forests. To investigate the influence of environmental and individual factors on <i>Rickettsia</i> prevalence, this study aimed to analyse the prevalence of SFG rickettsiae in ticks and small mammals in different small-scale habitats in central Germany for the first time. Small mammals of ten species and ticks of two species were collected from grasslands and forests in the Hainich-Dün region, central Germany. After species identification, DNA samples from 1098 ticks and ear snips of 1167 small mammals were screened for <i>Rickettsia</i> DNA by qPCR targeting the <i>gltA</i> gene. Positive samples were retested by conventional PCR targeting the <i>ompB</i> gene and sequencing. <i>Rickettsia</i> DNA was detected in eight out of ten small mammal species. Small mammal hosts from forests (14.0%) were significantly more often infected than those from grasslands (4.4%) (<i>p</i> < 0.001). The highest prevalence was found in the mostly forest-inhabiting genus <i>Apodemus</i> (14.8%) and the lowest in <i>Microtus</i> (6.6%), which inhabits grasslands. The prevalence was higher in <i>D. reticulatus</i> (46.3%) than in the <i>I. ricinus</i> complex (8.6%). Adult ticks were more often infected than nymphs (<i>p</i> = 0.0199). All sequenced rickettsiae in <i>I. ricinus</i> complex ticks were <i>R. helvetica</i>, and the ones in <i>D. reticulatus</i> were <i>R. raoultii</i>. Unlike adults, questing nymphs have had only one blood meal, which explains the higher prevalence in <i>I. ricinus</i> adults. Interestingly, habitat type did influence infection probability in small mammals, but did not in ticks. A possible explanation may be the high prevalence in <i>Apodemus flavicollis</i> and <i>A. sylvaticus</i> which were more abundant in the forest.