| Summary: | <p>Abstract</p> <p>Background</p> <p><it>Neoehrlichia mikurensis</it> s an emerging and vector-borne zoonosis: The first human disease cases were reported in 2010. Limited information is available about the prevalence and distribution of <it>Neoehrlichia mikurensis</it> in Europe, its natural life cycle and reservoir hosts. An <it>Ehrlichia</it>-like <it>schotti</it> variant has been described in questing <it>Ixodes ricinus</it> ticks, which could be identical to <it>Neoehrlichia mikurensis.</it></p> <p>Methods</p> <p>Three genetic markers, 16S rDNA, gltA and GroEL, of <it>Ehrlichia schotti</it>-positive tick lysates were amplified, sequenced and compared to sequences from <it>Neoehrlichia mikurensis</it>. Based on these DNA sequences, a multiplex real-time PCR was developed to specifically detect <it>Neoehrlichia mikurensis</it> in combination with <it>Anaplasma phagocytophilum</it> in tick lysates. Various tick species from different life-stages, particularly <it>Ixodes ricinus</it> nymphs<it>,</it> were collected from the vegetation or wildlife. Tick lysates and DNA derived from organs of wild rodents were tested by PCR-based methods for the presence of <it>Neoehrlichia mikurensis.</it> Prevalence of <it>Neoehrlichia mikurensis</it> was calculated together with confidence intervals using Fisher's exact test.</p> <p>Results</p> <p>The three genetic markers of <it>Ehrlichia schotti</it>-positive field isolates were similar or identical to <it>Neoehrlichia mikurensis</it>. <it>Neoehrlichia mikurensis</it> was found to be ubiquitously spread in the Netherlands and Belgium, but was not detected in the 401 tick samples from the UK. <it>Neoehrlichia mikurensis</it> was found in nymphs and adult <it>Ixodes ricinus</it> ticks, but neither in their larvae, nor in any other tick species tested. <it>Neoehrlichia mikurensis</it> was detected in diverse organs of some rodent species. Engorging ticks from red deer, European mouflon, wild boar and sheep were found positive for <it>Neoehrlichia mikurensis</it>.</p> <p>Conclusions</p> <p><it>Ehrlichia schotti</it> is similar, if not identical, to <it>Neoehrlichia mikurensis. Neoehrlichia mikurensis</it> is present in questing <it>Ixodes ricinus</it> ticks throughout the Netherlands and Belgium. We propose that <it>Ixodes ricinus</it> can transstadially, but not transovarially, transmit this microorganism, and that different rodent species may act as reservoir hosts. These data further imply that wildlife and humans are frequently exposed to <it>Neoehrlichia mikurensis-</it>infected ticks through tick bites. Future studies should aim to investigate to what extent <it>Neoehrlichia mikurensis</it> poses a risk to public health.</p>
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