Abstract
Leeches are frequently used in traditional Chinese medicine. However, they are potentially hazardous to human and animal health by transmitting several pathogens. Studies of diseases transmitted by leeches are scarce. The purpose of this study was to analyze the pathogens carried in pond-farmed medicinal leech in China. Leeches were collected from 6 farms in Hubei Province in central China. DNA was extracted from the internal organ of leeches to analyze the origin of blood meal. Leech genera were confirmed through amplification of 18S rRNA and mitochondrial gene cytochrome oxidase I (COI) gene by PCR and host animal species were identified through amplification of mitochondrial cytochrome b gene. Species of Ehrlichia in the leech specimens were screened with PCR using specific primers. PCR amplification and DNA sequencing showed that 620 leeches were Hirudinaria sp. Ehrlichia DNA was detected in 39 specimens from 2 farms. We obtained a total of 65 sequences of the cytB gene from 620 leech internal organ samples including sequences of human (n = 5), rat (n = 1), domestic pig (n = 10), duck (n = 23), goose (n = 12) and buffalo (n = 14). Phylogenetic analysis of the rrs and groEL gene sequences showed that Ehrlichia detected in the study were closely related to Ehrlichia sp. in ticks from Korea and Japan. To the best of our knowledge, this is the first report on Ehrlichia DNA being detected from leeches. Our findings provided new data on Ehrlichia spp. and farmed leech species in China.
Highlights
Various leech species have been used worldwide in complementary medicine for centuries
Phylogenetic analysis based on the rrs showed that Ehrlichia sequences detected from leeches formed a clade together with uncultured Ehrlichia species from ticks in Jeju Island and Yonaguni Island (Fig 5)
The genus Ehrlichia consists of several species of obligate Gram-negative intracellular bacteria that is transmitted to vertebrates by tick bites [21]
Summary
Various leech species have been used worldwide in complementary medicine for centuries. Leeches secrete a complex mixture of different pharmacologically and biologically active substances into the wound while feeding[1]. Previous studies indicated that mammalian viruses, bacteria and bacteriophages persisted in the gut of leeches in large numbers for 23 weeks to more than 6 months [2, 3]. Leeches fed on the blood of different wild animals might be expected to bring about severe diseases by transmitting infectious agents that cause erysipelas. Ehrlichia species in leeches from China the form of salaries for all authors, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section
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