Snakebite Issues in the Asia-Pacific

Snake-bite is a leading medical emergency in many countries in this vast region especially in Myanmar, Pakistan, Nepal, and New Guinea while India alone suffers an average of 46,000 deaths each year from this cause. Persistent morbidity is high but unquantified. In Cambodia there have been reports of snakebite amputees, desperate to gain access to prosthetic services, telling NGO’s that their injuries were due to land mines, in order to be considered for assistance. Ironically one of the main causes of snakebites in South-East Asia, the Malayan pit-viper (Calloselasma rhodostoma) is euphemistically referred to as a living land mine, for it’s habit of lying motionless among the weeds and leaf litter in rubber and oil palm estates, only to strike explosively if stepped on, or near. In Myanmar, snakebites by SIamese Russell’s vipers (Daboia siamensis) are a major cause of kidny injury leading to a need for dialysis, and in Papua New Guinea, lethal neurotoxins in the venom of taipan snakes (Oxyuranus scutellatus) cause irreversible nerve destruction that can condemn victims to death by airway obstruction (by a paralysed tongue) or slow suffocation when respiratory muscles in the chest cease functioning.

Malayan pit-viper (Calloselasma rhodostoma)

Siamese Russell’s viper (Daboia siamensis)

Malayan krait (Bungarus candidus)

Medically important snakes include 11 species of cobra (Naja), more than 15 kraits (Bungarus), the Australasian elapids and several species of vipers, notably Russell’s (Daboia) and saw-scaled vipers (Echis), and pit-vipers, notably habu’s (Protobothrops), mamushi’s (Gloydius) and Malayan pit-vipers (Calloselasma rhodostoma). In northern Viet Nam, China and Taiwan, bites by Sharp-nosed vipers (Deinagkistrodon acutus) are greatly feared, but the true medical importance is poorly documented. Green-coloured pit-vipers of which there are several species, including Cryptelytrops albolabris, the white-lipped green pit-viper, are a common cause of morbidity, if not mortality, in countries like Thailand, Cambodia, Laos and Viet Nam. Across most of Asia, the kraits (Bungarus) pose a nocturnal threat to sleeping people, as these lithe snakes wander into homes in seach of prey. Studies in Nepal suggest that the simple act of sleeping beneath a mosquito net, may prevent many of these nocturnal krait bites, and this approach could also be useful outside Asia, for example; in preventing bites by Mozambique spitting cobras (Naja mossambica) and stilleto snakes (Atractaspis) in Africa, as well as mosquito-borne diseases like malaria.

ANTIVENOMS

India, Pakistan, Myanmar, Thailand, Viet Nam, China, Taiwan, Indonesia and Australia have national antivenom producers but the safety and effectiveness of products from some of these countries is questionable. Three Global Snakebite Initiative partners, Instituto Clodomiro Picado (Costa Rica), the Australian Venom Research Unit (Australia) and the Charles Campbell Toxinology Centre (Papua New Guinea) are currently working together to conduct clinical trials of a new Papuan taipan antivenom for use in Papua New Guinea. A recurrent problem in the region is the inappropriate marketing of antivenoms from India in countries such as Cambodia and Papua New Guinea. These products have no efficacy against the venoms of local snakes, and are often sold at many times the Indian Pharmacy price, by wholesalers making a quick profit at the expense of human lives.

Antivenoms from three different Indian manufacturers in a hospital pharmacy in Pursat, western Cambodia. None of these products are suitable for treating the bites of Cambodian snakes.

The cost of antivenoms, their safety and effectiveness are common issues throughout not just Asia and the Pacific but other parts of the world as well. High quality antivenoms are expensive to produce and in developing nations expensive products limit availability, and encourage black-market activities and profiteering.

REGIONAL CHALLENGES

Medical infrastructure, training of medical staff and provision of antivenom and other important medical equipment for mechanical ventilation and renal replacement therapy varies greatly throughout the region. In many rural areas in Asia and New Guinea, hospitals have next to no equipment, and few trained staff. For these, and other reasons, traditional treatment of snake-bites remains very popular in rural areas of many countries. Vocational training in snakebite management is taught to health workers and doctors in Papua New Guinea and in Cambodia. WHO SEARO has published Guidelines for the management of snakebite, and these are available online (see link below).

Snakebite is a preventable injury.

Finding ways to effectively prevent snakebites is particularly challenging in the tropics of Asia and New Guinea. The simple concept of wearing inexpensive, but stout footwear offers the potential to prevent many snakebites, but rural people often lead barefoot lives. Forced solutions, such as importing cheap gumboots from India or China, are not effective options in communities where years of going shoeless causes feet to spread, making most mass-produced footwear uncomfortable to wear, discouraging its use. Affordable, comfortable shoes in realistic sizes for rural dwellers could literally prevent millions of snakebites every year across Asia and the Pacific. The Global Snakebite Initiative has had some preliminary contact with shoe-makers willing to explore the design and manufacturer of shoes to protect against snakebite, and will continue working towards this goal. Likewise there is an urgent need to reach a consensus agreement among experts on what constitutes the most appropriate, effective and safe, forms of first aid for delaying the effects of snakebites. The GSI’s Medical and Scientific Advisory Committee will be considering this issue, with the aim of producing a draft Guideline for discussion before the end of 2012.