Estimate of the burden of snakebites in sub-Saharan Africa: a meta-analytic approach.

Snakebites represent an important neglected public health problem in many developing countries. There is a lack of epidemiological data, which would be very useful for the organisation of snakebite management and provision of antivenom. An extensive literature search for the years 1970-2010 was performed. Data were analysed using meta-analysis to take into account the heterogeneity between the studies and their respective weight. Incidence, mortality and population at risk were estimated after stratification according to the environment (urban or rural) and survey methodologies (national, hospital or community studies). The incidence of snakebite was inversely correlated with population density. The number of envenomings was estimated at 314,078 [CI95% = 251,513-377,462], of which 95% occurred in rural areas. The remainder occurred in cities. The annual mortality was estimated at 7,331 [5,148-9,568], of which 97% occurred in a rural environment. The annual number of amputations ranged from 5,908 to 14,614. The population most at risk was young men engaged in agricultural or pastoral labours. Household surveys indicated that actual incidence and mortality were likely 3-5 times higher. The difference maybe explained by treatment seeking behaviour. However, incidences and mortalities reported here reflect the number of patients who attend modern health facilities, giving underestimated figures of the burden of snakebites in sub-Saharan Africa but realistic current requirements for antivenoms.