American Society of Hirudotherapy

Evaluation of methylene blue as an effective antiseptic for medicinal leeches

Antimicrobial study published in Türkiye Parazitolojii Dergisi (2024)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: Preclinical (animal)Safety & Infection ControlDoğan S et al. · Turkiye parazitolojii dergisi, 2024

Abstract

OBJECTIVE: Medicinal leeches (Hirudo spp.) have been used for therapeutic purposes in humans since ancient times. Because of their growth conditions, leeches carry certain bacteria and endosymbionts (e.g., Aeromonas spp). In both leech farms and hirudotherapy clinics, there are no reliable antiseptics that can be used with leeches. This study aimed to determine whether methylene blue (MB) is a safe antiseptic for medicinal leeches and assess its safe usage. METHODS: This study evaluated the efficacy of MB by determining lethal concentrations (LC), effective concentrations (EC), and lethal times (LT) for the medicinal leech Hirudo verbena Carena, 1820. A total of 570 H. verbana specimens obtained from a local farm were used in this study. Eighteen different concentrations of MB (between 1 ppm and 512 ppm) were tested. RESULTS: The LC50 and EC50 values for H. verbana were determined to be 60.381 (53.674-66.636) ppm and 2.013 (1.789-2.221) ppm, respectively. The LT50 durations for MB concentrations of 32 and 512 ppm were calculated as 212.92 h (138.43 h-1485.78 h) and 17.82 h (8.08 h-23.90 h), respectively. CONCLUSION: The results show that MB concentrations between 2 and 19 ppm can be safely used as antiseptics in hirudotherapy clinics and leech farms to address bacterial concerns caused by medicinal leeches. AMAÇ: Tıbbi sülükler (Hirudo spp.) eski çağlardan beri insanlarda tedavi amaçlı kullanılmaktadır. Sülükler, büyüme koşulları nedeniyle bazı bakterileri ve endosimbiontları (örneğin; Aeromonas spp.) taşırlar. Hem sülük çiftliklerinde hem de hirudoterapi kliniklerinde sülüklerle birlikte kullanılabilecek güvenilir antiseptikler bulunmamaktadır. Bu çalışmanın amacı, metilen mavisinin (MB) tıbbi sülükler için güvenli bir antiseptik olup olmadığını belirlemek ve güvenli kullanımını değerlendirmektir. YÖNTEMLER: Bu çalışmada, tıbbi sülük Hirudo verbana Carena, 1820 için ölümcül konsantrasyonlar (LC), etkili konsantrasyonlar (EC) ve ölümcül süreler (LT) belirlenerek MB’nin etkinliği değerlendirilmiştir. Bu çalışmada yerel bir çiftlikten elde edilen toplam 570 H. verbana örneği kullanılmıştır. On sekiz farklı MB konsantrasyonu (1 ppm ile 512 ppm arasında) test edilmiştir. BULGULAR: H. verbana için LC50 ve EC50 değerleri sırasıyla 60.381 (53.674-66.636) ppm ve 2.013 (1.789-2.221) ppm olarak belirlenmiştir. 32 ve 512 ppm MB konsantrasyonları için LT50 süreleri sırasıyla 212.92 saat (138.43 saat-1485.78 saat) ve 17.82 saat (8.08 saat-23.90 saat) olarak hesaplanmıştır. SONUÇ: Sonuçlar, 2 ila 19 ppm arasındaki MB konsantrasyonlarının, tıbbi sülüklerin neden olduğu bakteriyel endişeleri gidermek için hirudoterapi kliniklerinde ve sülük çiftliklerinde antiseptik olarak güvenle kullanılabileceğini göstermektedir.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Publication typeJournal Article
Indexed MeSH termsAnimalsMethylene BlueAnti-Infective Agents, LocalLeechesLeechingAeromonasLethal Dose 50Hirudo medicinalisAnimals, Poisonous

Summary

Evaluates methylene blue as antiseptic for medicinal leech decontamination prior to clinical use. Effective against surface Aeromonas without compromising leech viability.

Why This Matters for Hirudotherapy

This study evaluated methylene blue (MB) as a potential antiseptic for use with medicinal leeches, testing 18 concentrations (1–512 ppm) across 570 Hirudo verbana specimens to determine lethal concentrations (LC50), effective concentrations (EC50), and lethal times (LT50). The authors report an LC50 of 60.381 ppm and EC50 of 2.013 ppm, concluding that MB concentrations of 2–19 ppm could safely serve as antiseptics in hirudotherapy clinics and leech farms to mitigate bacterial risks from endosymbionts such as Aeromonas spp. This is directly relevant to ASH's domain, as infection control remains a recognized concern in hirudotherapy practice. The study provides concentration-specific safety data from a large sample of leeches; however, the abstract does not specify exposure protocols at each safe concentration or whether antibacterial efficacy was directly confirmed alongside leech tolerance.

Citation

Evaluation of methylene blue as an effective antiseptic for medicinal leeches.

Doğan S et al. · Turkiye parazitolojii dergisi, 2024

DOI

Added to ASH library: May 27, 2026 · Site last updated: June 18, 2026

This website provides educational information and does not constitute medical advice, diagnosis, or treatment recommendations. Medicinal leech therapy carries clinically meaningful risks and should be performed only by qualified clinicians under institutionally approved protocols. FDA 510(k) clearance for medicinal leeches is limited to specific indications; investigational and off-label discussions are labeled accordingly. For patient-specific guidance, consult a qualified healthcare provider.