Viral infection risks for patients using the finished product Hirudo verbana (medicinal leech)

The virological safety of medicinal leeches has to be ensured prior to their use on patients. While leeches can be kept and bred under standardized conditions, feeding them horse blood adds a non-standardized component, which poses some risk of infection of the treated patients. Here, we investigated the speed at which blood-borne viruses are degraded by the microbial flora in the leech intestine, in order to define the safety of the product and the length of the necessary quarantine period prior to its administration to patients. Feeding blood was spiked with bovine viral diarrhea virus (BVDV), reovirus, and murine parvovirus (10⁷ ID₅₀?ml^?1). The virus titer in the intestinal contents of the leeches was determined using permissive cell cultures and compared to that of the original virus titer at the following time points: immediately after feeding; after 3, 14, and 30 days; and monthly thereafter until the 7th month. The BVDV titer was below the detection limit of 10¹ TCID₅₀?ml^?1 after 3 months, while reovirus and murine parvovirus titers were undetectable after 4 months. No positive virus findings were obtained at later time points. Thus, when fed the blood of vertebrates, the finished product “Medicinal leech, Hirudo verbana” can be considered virologically safe if the animals are maintained at 20 °C, which corresponds to their natural habitat conditions and ensures a high metabolic rate. Therefore, after the last feeding, a quarantine period of 4–6 months and appropriate care at room temperature, which supports microbial degradation and digestive processes, are recommended.     

Proton-induced chloride current and voltage-activated Na+ and Ca2+ currents in embryonic neurons from the medicinal leech (Hirudo medicinalis)

Voltage-activated ionic currents and currents induced by step changes in proton concentration (pH 7.9-6.7) were studied in early embryonic neurons from Hirudo medicinalis. Ganglia were dissociated at embryonic day (E) 8-15, and the largest neurons were investigated using whole-cell patch clamp recording. All cells studied displayed voltage-activated Na+ and Ca2+ currents. Step changes in pH induced sustained currents which reversed at the equilibrium potential for Cl- and were blocked by substituting Cl- with acetate or sulfate. These currents thus differ in their ion selectivity from proton-induced currents in vertebrate neurons which are carried by Na+.     

Elimination of symbiotic Aeromonas spp. from the intestinal tract of the medicinal leech,Hirudo medicinalis,using ciprofloxacin feeding

The use of the medicinal leech (Hirudo medicinalis) in promoting venous drainage in tissues whose vitality is threatened by venous congestion and obstruction, especially in plastic and reconstructive surgery, has been complicated by infections caused by Aeromonas spp. These are leech endosymbionts for which patients undergoing hirudotherapy frequently receive systemic chemoprophylaxis. In order to evaluate the possibility of rendering leeches safe for use on patients, H. medicinalis were fed artificially with a 2 g/L arginine solution (used as a phagostimulant) supplemented with ciprofloxacin (100 mg/L). Aeromonads were detected in 57 out of 80 control leeches (71.3%), but in none of the 56 leeches treated with ciprofloxacin (p <0.001). Treated leeches survived for up to 4 months. Tested weekly, 61% of these leeches took human blood for at least 4 weeks after treatment and all remained negative for aeromonads. All water samples in which leeches were kept before treatment were contaminated with Aeromonas spp.; none were detected in any of the NaCl/arginine solutions with which treated animals were fed. Molecular characterization of two phenotypically distinct isolates using gyrB sequencing showed that one clustered tightly with A. veronii and the other was closely related to A. media. Other environmental bacteria and fungi were isolated from 26.5% of treated leeches that had taken a blood meal 1–4 weeks after treatment. Ciprofloxacin reduced the number of leech-associated aeromonads to undetectable levels for extended periods. Most treated leeches were ready to take a blood meal after treatment, suggesting the possibility of using ciprofloxacin-treated leeches instead of chemoprophylaxis in patients undergoing hirudotherapy.     

A new species of Polylopadium Brennan & Jones, 1961 (Acari: Trombiculidae) from cricetid rodents, Peru with description of a new character for the genus and a key to the species

peruensis is described as new from specimens collected from Oryzomys yunganus, Proechimys quadruplicatus, and Oryzomys megacephalus taken in Peru. A new character of a nude tactile seta on femur III is noted for the genus and a key to the species of Polylopadium is presented.     

Segmental control of midbody peristalsis during the consummatory phase of feeding in the medicinal leech, Hirudo medicinalis

The ingestive behavior of the medicinal leech includes peristalsis-like movements of the midbody that are organized into both rostral-to-caudal and caudal-to-rostral waves (C. M. Lent, K. H. Fliegner, E. Freedman, & M. H. Dickenson, 1988). The neuronal control of this behavior is unknown. Using surgical manipulations and electromyograms, the authors show that (a) the head and tail ganglia are not necessary for this behavior; (b) the circuit is distributed, with components reiterated along the length of the leech; (c) excitatory signals transmitted from rostral segments via the nerve cord can initiate peristalsis in "empty" caudal segments; (d) inhibitory signals from caudal segments limit the frequency of peristalsis; and (e) stretch of the gut and/or body wall is sufficient to produce peristalsis in the absence of heat or chemical cues. These results are compared with peristalsis in the digestive tract of mammals. The leech may be a good model for studying peristalsis-like behaviors at the cellular level.     

Bleeding in human volunteers from the bite of the American medicinal leech Macrobdella decora compared with its European counterpart Hirudo medicinalis

In this paper the effectiveness of the so-called American medicinal leech Macrobdella decora in overcoming human haemostasis is compared to that of the European medicinal leach Hirudo medicinalis. Thrombin-clotting times indicated that M. decora prevents coagulation of human blood by means of anti-thrombin activity. Our findings suggest that its role is similar to that of hirudin. In human volunteers, the duration of bleeding from the bite of M. decora (mean = 73 min; n = 18) is significantly shorter than H. medicinalis (mean = 600 min; n = 15). The mean concentration of anti-thrombin units in each specimen of M. decora and H. medicinalis is 100 and 285 AT-U, respectively. These findings support the concept that H. medicinalis is more advanced in terms of haematophagous predation. Despite similar feeding durations by both species of leech (means = 68 min and 70.5 min by M. decora and H. medicinalis, respectively), the mean increase in body weight of M. decora was only 58% compared to 460% in H. medicinalis.