Molecular detection of Bartonella spp. in terrestrial leeches (Haemadipsa rjukjuana) feeding on human and animal blood in Gageo-do, Republic of Korea

Background: Leeches can transmit pathogens and are therefore potentially hazardous to human and animal health. However, only a few studies of diseases transmitted by land leeches have been reported. The purpose of the present study was to analyse which pathogens are carried in Haemadipsa rjukjuana, the first recorded sanguivorous land leech in the Republic of Korea (ROK). Findings: A total of 173 H. rjukjuana were collected from Mt. Dock-Sil on Gageo-do Island, ROK during July 2011. Conventional PCR was conducted for analysis of the origin of blood meal, as well as for detection of species of Anaplasma, Bartonella, Borrelia, Ehrlichia, Rickettsia, and Wolbachia in the leech specimens. Bartonella DNA was detected in eight of the specimens studied based on partial ITS sequence analysis. Seven of the DNA samples were closely related to Bartonella grahamii (99.6-100 % similarity), and one sample exhibited a 90.6 % similarity with Bartonella sp. from Taiwan. Sequences of the mitochondrial cytochrome b gene were generated for a total of 35 of the 173 leech internal organ samples. These included sequences of human (n = 10), mouse (n = 8), weasel (n = 6) and bird (n = 11) origin. Of these 35 sequences, 68.5 % were from mammals, including humans, and 31.4 % were from migratory birds that pass through Gageo-do, ROK. Conclusions: Although the present study does not provide evidence that leeches indeed transmit Bartonella species to hosts directly, to our knowledge this is the first report on Bartonella DNA being detected from leeches. Therefore, further studies are needed to explore the possibility of zoonotic pathogen transmission by land leeches.