Microbiota Dynamics: A Key Factor in Hirudotherapy-Related Infections?
Research article published in Microorganisms (2025)
Abstract
The gastrointestinal microbiota of medicinal leeches is particularly interesting due to their blood-feeding habits, increasing medical use, and risk of pathogen transmission. Three groups of Hirudo verbana were used to study the leech microbiota: farmed leeches fasting for a long time, farmed leeches recently fed with bovine blood, and wild specimens fed with amphibian blood. The microbiota of the leeches' mouth, pharynx, crop, and intestine was analyzed. Metasequencing analyses were performed using amplification of the 16S rRNA V3-V4 region on a NovaSeq Illumina platform. The relative abundance of bacterial microbiota included environmental bacteria from the families Rhizobiaceae, Comamonadaceae, Sphingobacteriaceae, Phreatobacteraceae, Myxococcaceae, Chitinophagaceae, Rhodospirillaceae, and Bdellovibrionaceae, as well as symbiotic/probiotic bacteria such as Mucinivorans, Aeromonas, Vagococcus, Lactobacillales, and Morganella. Significant differences were found in the different regions of the digestive system among the three groups of leeches, and environmental bacteria were present in all groups to varying degrees. A negative correlation was found between the dominant environmental and the symbiotic/probiotic bacteria. In contrast, a positive correlation was found between environmental and symbiotic/probiotic bacteria, indicating their association with host factors. Microbiota diversity, abundance, and bacterial correlations may be influenced by factors such as the leech's fasting state, blood meal source, and environmental conditions. The identified opportunistic pathogens, such as Rickettsia, Anaplasma, and Treponema, identified for the first time in H. verbana, should be taken into consideration when using this leech in hirudotherapy. Our results show that extensive screening for opportunistic and pathogenic agents should be performed on leeches intended for medical use. Long-fasting leeches and leeches cultured in specialized farms are recommended for hirudotherapy.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
Microbiota Dynamics: A Key Factor in Hirudotherapy-Related Infections?.
Why This Matters for Hirudotherapy
This study analyzed the bacterial microbiota of the digestive tracts of Hirudo verbana medicinal leeches from different environments, comparing farmed fasting leeches, recently fed farmed leeches, and wild specimens. It is directly relevant to hirudotherapy safety, demonstrating that the leech microbiome and the presence of opportunistic pathogens like Rickettsia, Anaplasma, and Treponema vary significantly based on the leech's fasting state, blood meal source, and environmental conditions. The authors recommend using long-fasting leeches cultured in specialized farms to minimize the risk of transmitting pathogens during therapy. As a caveat, these findings rely on preclinical metasequencing analyses of leeches and do not quantify clinical infection rates in human patients undergoing hirudotherapy.
Citation
Microbiota Dynamics: A Key Factor in Hirudotherapy-Related Infections?
Karasartova D et al. · Microorganisms, 2025
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