Sustained bleeding from bites of hatchling leeches

Prolongation of haemostatic parameters in the host achieved by hatchlingHirudo medicinalis differs quantitatively but not qualitatively from those achieved by adult leeches. The duration and the rate of blood loss from the bite wounds, the gain in body weight of leeches and the duration of feeding each increase with successive feeding episodes. The mean duration of bleeding from bite wounds of hatchling leeches feeding for the first time on human volunteers was 43 min compared to 6 min from control incisions and 600 min in adult leeches. The mean ‘whole body’ concentration of hirudin in 2-week-old hatchlings was 10 antithrombin units (AT-U) compared to 285 AT-U in the head of each adult leech.