Annual Incidence of Snake Bite in Rural Bangladesh

Citation: Rahman R, Faiz MA, Selim S, Rahman B, Basher A, et al. ( Annual Incidence of Snake Bite in Rural Bangladesh Ridwanur Rahman M. Abul Faiz Shahjada Selim Bayzidur Rahman Ariful Basher Alison Jones Catherine d'Este Moazzem Hossain Ziaul Islam Habib Ahmed Abul Hasnat Milton David G. Lalloo, Liverpool School of Tropical Medicine, United Kingdom Background: Snake bite is a neglected public health problem in the world and one of the major causes of mortality and morbidity in many areas, particularly in the rural tropics. It also poses substantial economic burdens on the snake bite victims due to treatment related expenditure and loss of productivity. An accurate estimate of the risk of snake bite is largely unknown for most countries in the developing world, especially South-East Asia. Methodology/Principal Findings: We undertook a national epidemiological survey to determine the annual incidence density of snake bite among the rural Bangladeshi population. Information on frequency of snake bite and individuals' length of stay in selected households over the preceding twelve months was rigorously collected from the respondents through an interviewer administered questionnaire. Point estimates and confidence intervals of the incidence density of snake bite, weighted and adjusted for the multi-stage cluster sampling design, were obtained. Out of 18,857 study participants, over one year a total of 98 snake bites, including one death were reported in rural Bangladesh. The estimated incidence density of snake bite is 623.4 / 100,000 person years (95% C I 513.4-789.2 /100,000 person years). Biting occurs mostly when individuals are at work. The majority of the victims (71%) receive snake bites to their lower extremities. Eightysix percent of the victims received some form of management within two hours of snake bite, although only three percent of the victims went directly to either a medical doctor or a hospital. Conclusions/Significance: Incidence density of snake bite in rural Bangladesh is substantially higher than previously estimated. This is likely due to better ascertainment of the incidence through a population based survey. Poor access to health services increases snake bite related morbidity and mortality; therefore, effective public health actions are warranted. - Funding: The study was funded by the Ministry of Health and Family Welfare, Peoples Republic of Bangladesh and The World Bank, Bangladesh office. The authors also thank the University of Newcastle, Australia for supporting AHMs visit to Bangladesh under Early career researchers grant. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Snake bite particularly in the rural tropics 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 [1]. Snake bite is the single most important cause of envenoming worldwide and results in substantial mortality in many parts of Africa, Asia, and the Americas [2]. Snake bite is significantly neglected as a public health problem in the world as evidenced by the lack of available incidence data from most of the rural tropics where snake bites occur frequently. Global snakebites (envenomings) incidence has been estimated as 500,000 and mortality between 3000040000 per year [3]. Chippaiux estimated that venomous snakes cause 5.4 million bites, approximately 2.5 million envenomings and over 125,000 deaths worldwide annually [4]. White estimated more than three million bites per year resulting in more than 150,000 deaths [5]. Details of the methods used to estimate these numbers have not been clearly described. More recently Anuradhani et al reported that, globally at least 421,000 envenomings occur annually, but this may be as high as 1,841,000 [6]. According to this estimate, the highest numbers of envenomings are estimated for South Asia (121,000) followed by South East Asia (111,000), and East SubSaharan Africa (43000). Global estimates of snakebite envenomings and deaths seem to be more accurate than previous estimates due to improved study methodology. However, this data may be inaccurate because of assumptions used in the calculations, lack of information relating to snake bites and related deaths in rural tropics. It is likely that the true numbers of these events may be substantially different from the estimates presented in this report. The true incidence of snake bite in rural Bangladesh is largely unknown. Previously, an incidence of 4.3 snake bites per 100,000 populations was reported with approximately 2000 deaths occurring annually in Bangladesh [7]. This estimate is based on data from a small study. During 198889, a small survey was conducted in 50 Upazillas (sub-districts) of Bangladesh that Snake bite is one of the major causes of morbidity and mortality in many rural tropical areas. As a neglected public health problem, estimate of the risk is largely unknown. However, the associated personal and economic impact of snake bite is substantial across developing countries. This national survey investigated the risk and consequences of snake bite among the rural Bangladeshi population. We surveyed 18857 individuals from 24 out of 64 districts in Bangladesh where 98 snake bites including one death were reported. The estimated incidence density of snake bite is 623.4/ 100,000 person years (95% CI: 513.4 789.2/100,000 person years). Biting occurs mostly when individuals are at work. The majority of the victims (71%) received snake bites to their lower extremities. Eighty-six percent of the victims received some form of management within two hours of snake bite, although only three percent of them went directly to either a medical doctor or a hospital. The observed rate of snake bite in rural Bangladesh is substantially higher than anticipated. This coupled with poor access to health services led to an increase in related morbidity and mortality. An improvement in public health actions is therefore warranted. recorded 764 episodes of snakebite, of which 168 (22%) died [8]. Due to methodological limitations, these estimates are unlikely to be representative of the whole country population. According to Faiz, 1666 snake bite victims attended to the Chittagong Medical College Hospital (CMCH) for treatment between 1993 and 2003. Among those victims, 28.5% were bitten by poisonous snakes and only eight (0.5%) died [1]. In this context, this cross-sectional survey was carried out to determine the annual incidence density of snake bite in rural Bangladesh. In addition, the study also developed an epidemiologic profile of snake bites that includes age and sex specific incidence of snake bites, consequence of snake bite, treatment seeking behaviour of the patients, seasonal trend, and geographi (...truncated)