A SUMMARY OF THE SNAKEBITE SITUATION IN BANGLADESH
Dr Aniruddha Ghose
Snake bite is a result of an unfortunate accidental interaction between a snake and a human victim. It is the single most important toxin-related injury, causing substantial mortality in many parts of the Africa, Asia, and the Americas.
Snake bite is a burning public health issue in Bangladesh as a disaster prone country and its geographical position and climatic conditions. The geographical position of Bangladesh in the junction of Indo-Malayan, Indo-Chinese and Indo-Himalayan Regions provides excellent opportunities for having a great diversity of habitats for snakes and as well as other wild animals.
Snake bite, particularly in the rural Bangladesh is a major cause of mortality and morbidity, and it has a significant impact on human health and economy through treatment related expenditure and loss of productivity.
Most often the victim of snake bite is a poor, young and active individual. Biting occurs mostly when individuals are at work, engaging in activities such as cultivation, fishing, plantation, wood collection, or tending crops or gardens. However, bites are fairly common when the victims are walking on rural foot paths or while sleeping in the floor. During the monsoon, snake bite occurrences increase as snakes leave their shelter due to rainfall. Most of the houses in countryside of Bangladesh are not brick and the snakes sometimes live in the holes of the muddy floors. Moreover most of the houses have homestead bush, which offers an ideal habitats for snakes. As a result, events of snake bites are also common when people are at home. To go to the toilet and for other domestic purposes, people often come out of their houses and become victims. Village people store grains including paddy rice in their bedroom, and keep the poultry in the same dwelling house which also provides shelter to the snakes, therefore increasing the risk of snake bite. Snake bite envenoming in Bangladesh is also an occupational disease of the young rural poor people who suffer bites while engaged in physical work, most often during cultivation. Children have a particularly high risk of dying or suffering permanent disability from snake bite envenoming.
SNAKEBITE EPIDEMIOLOGY IN BANGLADESH
In the absence of any epidemiological survey data, there was a dearth of information about snake bite from Bangladesh. During 1988-89, a small survey was conducted in 50 Upazillas (sub-districts) of Bangladesh recorded 764 occurrences of snake bite, of which 168 (22%) died. A postal survey conducted in 21 of the 65 administrative districts in 1995–1996 estimated an annual incidence of 4.3 per 100,000 populations and a case fatality of 20%. In this study, Chittagong Division and Barisal Division had the highest annual incidence of snake bites (7 per 100,000; Sarkar et al., 1999). These estimates were based on data from small studies and due to methodological limitations; the estimates were unlikely to be representative of the whole country population. According to Faiz (2006) 1666 snake bite victims attended the Chittagong Medical College Hospital (CMCH) for treatment during 1993 to 2003. Among those victims, 28.5% were bitten by venomous snakes and only eight (0.5%) died. Although the case fatality for CMCH is very low, it is usually very high in many rural areas. For example, five (25%) out of 20 victims, who attended Bashkhali Upazilla Health Complex (sub district level hospital) died.
It therefore seemed essential to conduct a countrywide study to determine the extent and magnitude of snake bites. Furthermore, it is imperative to assess epidemiological scenario of snake bites and its consequences in the context of rural Bangladesh as this is mainly an issue for rural areas.
A government supported, nationwide community-based epidemiological study of snake bite and its socioeconomic consequences in Bangladesh was recently finished. The detailed results are yet to be published but the preliminary data suggests a much higher incidence (as anticipated) and morbidity and mortality, putting snake bite as the second commonest cause of unnatural deaths. The study findings would be useful for planning and formulating strategies and specific interventions to combat snake bite related health problems in Bangladesh.
Based on records of the surveillance system of the Directorate General of Health Services (DGHS) snake bite envenoming was identified as a leading cause of mortality in the 2007 flood disaster, second only to drowning. DGHS data suggested a similar situation in the 2004 flood disaster. Clinical observation suggests increased numbers of snake bite admissions in the Chittagong region after earthquakes and minor seismic activities (Faiz et al., unpublished data). This estimate assumes an annual occurrence of extreme weather events whose consequences for the affected parts of the population in Bangladesh qualify them as natural disasters, however taking into account that the geographic area and the number of population affected as well as the severity and duration of the events are expected to be highly variable from year to year.
SNAKES OF MEDICAL IMPORTANCE
Bites by green pitvipers (Cryptelytrops erythrurus and other species), cobras (Naja species) and kraits (Bungarus) are the most commonly identified ones in Bangladesh. Neurotoxic envenoming by kraits and cobras is the principal cause of snake bite mortality in Bangladesh.
Recent studies revealed that at least five different species of krait contribute to snake bite mortality in Bangladesh and Nepal (unpublished data). Based on their frequencies among proven krait bites in Bangladesh and their geographical distribution, we presently estimate that Wall’s Krait (Bungarus walli) causes about 40% of all krait bites in the country, the Greater Black Krait (Bungarus niger) and the Common Krait (Bungarus caeruleus) about 28% each, and the Banded Krait (Bungarus fasciatus) and Lesser Black Krait (Bungarus lividus) about 2% each. In Bangladesh, Bungarus lividus is so far known only from the northwest. Bungarus walli and B. caeruleus are not known to occur in southeastern Bangladesh. Bungarus fasciatus and B. niger occur throughout the country.
Among the cobras, Naja kaouthia is expected to occur throughout the country and to cause the majority of cobra bites. It is the only species of Naja found in southeastern Bangladesh (here defined to include Chittagong District, Cox’s Bazar District, and the three Chittagong Hill Tract Districts). Naja naja is known from the area around Dhaka and expected to be continuously distributed at least to the west and north of the capital. Its southern and eastern distributional limits are not known. King Cobras (Ophiophagus hannah) occur wherever relatively undisturbed bamboo stands and forests remain in Bangladesh, but have not been documented to have caused envenoming bites in recent years.
Russell’s Viper (Daboia russelii) appears to be rare and its distribution patchy and/or restricted to western and northern parts of the country. There have been no recent reports of proven cases of Russell’s Viper envenoming in Bangladesh. Anecdotal notes (Banerji 1929) suggest that envenoming by Russell’s viper used to occur in the southwest (Assasuni and Shamnagar in Satkhira District; Koyra and Paikgacha in Khulna District) and possibly around Rajshahi and Dinajpur in the west and northwest of Bangladesh. There is no evidence to suggest that Saw-scaled Vipers (Echis species) occur anywhere in Bangladesh.
Sea snakes also constitute an occupational hazard for fishermen in Bangladesh but the incidence of their bites is unknown.
The field of ‘Snakes and snake bite’ has a mythological fragrance in the mind of people in this part of the world. Treatment of snake bite was largely dominated by traditional snake charmers (Ozha). People used to be content with their traditional methods of tight tourniquet, multiple incisions at bite site, application of herbal products and different rituals. The outcome was determined by chance. Even the medical professionals were not well aware of the scientific methods of management. The first initiative was undertaken by Professor MA Faiz, a renowned internist and medical researcher of this country. He established a snake bite study clinic in a medicine ward in Chittagong Medical College Hospital, situated at south-eastern part of the country. He started to use antivenom (polyvalent), and conducted several public awareness meeting in rural areas involving the traditional snake charmers/healers. With some successes and ‘miraculous’ recovery of nearly dead people it soon became popular and well known in public. With repeated presentations at different scientific forums at home and abroad, the professionals and the policy makers were oriented. Prof MA Faiz developed the Bangladesh National Guidelines for Treatment of Snake Bites. Then it was felt that the skill and knowledge of management has to be dissipated among the general physicians attending the victims at the primary level of health care. The training module (Learner’s guide, Teacher’s guide) was then developed.
So far more than 1000 physicians have been trained through an ongoing program of DGHS. Several BCC materials have also been developed. It was mostly the effort of a single person that snake bite and its management has gained some success and a momentum. Now many of his students and colleagues are doing research in this field. Following his examples and due to initiatives of DGHS snake bite is now recognized as an eminently treatable medical condition in Bangladesh.