Original Article

Comparative Haematology International

, Volume 2, Issue 2, pp 75-78

First online:

The leech as a tool for studying comparative haematology

  • R. MunroAffiliated withHaematology Department, Morriston Hospital
  • , M. SiddallAffiliated withDepartment of Zoology, University of Toronto
  • , S. S. DesserAffiliated withDepartment of Zoology, University of Toronto
  • , R. T. SawyerAffiliated withBiopharm (UK) Ltd

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Abstract

The bite of the North American leech Macrobdella decora results in much less prolonged bleeding in fish (8 min; control = 1 min) and amphibians (11.5 min; control = 1.5 min) than in mammals (humans) (73 min; control = 6 min). Coagulation of blood flowing from leech bite wounds is initially prolonged in frogs (4.3 min; control = 2 min) and humans (5.8 min; control = 2.5 min), but gradually returns to normal during the first 10 min after the termination of feeding. Although duration of feeding is similar in fish (mean = 62 min), amphibian (mean = 79 min) and human (mean = 68 min) hosts, the gain in body weight of leeches feeding on fish (mean = 11%) and amphibians (mean = 14%) is much less than those feeding on humans (mean = 58%). Bleeding in a frog heavily infected with the intrathrombocytic yeast Thrombocytozoons ranarum was abnormal from control incisions (>20 min) and from a leech bite wound (>140 min) suggesting impairment of thrombocyte function. This comparative approach to leech — host haematology offers a methodology into understanding the biological context in which the leech antithrombin (hirudin) evolved, as well as the evolution of vertebrate haemostatic mechanisms.

Keywords

Bleeding Fish Frog Haemostasis Hirudin Leech Platelet Thrombocyte