Microbiota Dynamics: A Key Factor in Hirudotherapy-Related Infections?
Microbiome study 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
16S rRNA metagenomic study of leech gastrointestinal microbiota across mouth, pharynx, crop and intestine in farmed (fed/fasting) versus wild leeches. Identifies opportunistic pathogens and recommends long-fasting farm-raised leeches for hirudotherapy.
Why This Matters for Hirudotherapy
This study investigates the gastrointestinal and mouth microbiota of the medicinal leech Hirudo verbana, comparing farmed, fasted, and wild specimens to understand the dynamics of hirudotherapy-related infections. The research is highly relevant to the American Society of Hirudotherapy as it directly addresses patient safety by identifying opportunistic pathogens like Rickettsia, Anaplasma, and Treponema in leeches intended for medical use. The authors recommend using long-fasting leeches from specialized farms to mitigate infection risks. While the study provides crucial safety data for clinical practice, its scope is limited to microbial ecology and does not assess the therapeutic efficacy of the leeches' secretions.
Citation
Microbiota Dynamics: A Key Factor in Hirudotherapy-Related Infections?
Karasartova D et al. · Microorganisms, 2025
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