Evolution of herpetology and management of snakebite in Sri Lanka

Abstract

The origins of ophiology, and responses to snakebites, are thought to have begun with prehistoric peoples. Later inhabitants developed a system of herbal remedies of snakebite, usually termed 'traditional snakebite treatment' with an extensive collection of written material. The modern era saw research into venoms and their effects by scientists following western traditions, leading to the development of antivenoms against specific snakes. Snakebite is an "occupational rural hazard". So said H. A. Reid, [1] the world-renowned authority on sea snake envenoming in the nineteen-fifties. He later established the Alistair Reid Venom Research Unit of the Liverpool School of Tropical Medicine in 1963, now named the Centre for Snakebite Research Interventions [2]. Epidemiological studies of snakebite in Sri Lanka have shown that snakebite is indeed an occupational rural health hazard [3, 4, 5]. Ten of the nineteen families of snakes described are found in Sri Lanka, there being 105 species in 47 genera, including 15 species of sea snakes. Thirty-nine species possess venom secreting glands associated with fangs. Among them, only six species of terrestrial snakes, namely, Russell's viper (Daboia russelii), cobra (Naja naja), common krait (Bungarus caeruleus), Ceylon krait (Bungarus ceylonicus), saw scaled viper (Echis carinatus) and the hump-nosed pit vipers (Hypnale hypnale, H. nepa and H. zara) are highly venomous-envenoming by these snakes is possibly life-threatening, fatalities having been recorded. All fifteen species of sea snakes inhabiting the coastal waters of Sri Lanka are highly venomous. Fishermen release hundreds of sea snakes trapped in their nets daily, but bites are rare as most are mild-tempered. An exception is the beak-nosed sea snake (Enhydrina schistosa, new taxonomy Hydrophis schistosa) found in lagoons of the northwest coast [6]. Sri Lanka is a small tropical island of 65,610 km 2 situated north of the equator between 5° and 10° latitude with a rich biodiversity and varied geography. Rainfall and climate divide the country into three zones. The dry zone occupies 65% of the country extending from the north to the foothills of the central hilly terrain, receiving less rain, mainly from the northeast monsoon. The wet zone (23%) is confined to the southwest of the island, receiving the highest annual rainfall from both the southwest and the northeast monsoons, as well as from inter-monsoonal rains. Lying in between is the intermediate zone (12%) [7]. Most of the venomous snakebites occur in the dry zone where paddy (rice) farming is common. Cobras and Russell's vipers are widely