The epidemiology of snakebites in tropical regions differs considerably from that seen in more temperate climates. In general, the absolute number of venomous snakes is higher in the tropics, and snakes are often located in areas of high population density. The prevalence of bites is also higher due to differences in agricultural and hunting practices, frequent flooding, lack of adequate footwear in many locations, and housing that allows access of snakes into living areas. The annual mortality of snakebite in India may exceed 20,000. Snakebite is said to be the 5th most common cause of death in Myanmar. In some indigenous populations in South America, up to 20% of adult deaths are from snakebite. Places where snakebites are common are often in remote locations where medical care may not be immediately available. Signs and symptoms depend on the type of envenomation and the amount of toxin injected. Local pain, swelling, and blistering are seen with many snakebites. Clotting disturbances, frank hemorrhage, and shock are seen with many viper bites, while neurotoxicity can be seen with elapid and sea snake bites.
Fer-de-Lance (Bothrops jararaca). Fer-de-Lance, French for “lance head,” refers to a number of venomous pit vipers of the genus Bothrops in Central and South America (B atrox, B asper, B jararaca, B lanceolatus). This family of snakes is responsible for more deaths than any other New World snake. (Photo contributor: Cybele Sabino Lisboa, BSc.)
Fer-de-Lance Bite. This patient was bitten on the index finger by a Fer-de-Lance snake while clearing bush in rural Peru. Note the ecchymosis proximal to the bite. (Photo contributors: Seth W. Wright, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)
Fer-de-Lance Bite (Late). Local tissue destruction at the site of a Bothrops atrox bite in a Guyanese teenager. (Photo contributor: Ian Jones, MD.)
Old World Viper Bite. Local hemorrhagic manifestations at the site of a snake bite in a Syrian man. Old World vipers lack the heat-sensing pits of the pit vipers. Bites can cause significant hemorrhagic, coagulopathy, and local tissue complications. (Photo contributor: Seth W. Wright, MD.)
Clotting Test. Positive results of a 20-minute whole blood clotting test are seen with the blood from a man bitten by a Russell’s viper. Lack of clotting at 20 minutes correlates closely with other clotting studies. (Photo contributor: Christian Medical College, Vellore, India.)
Management and Disposition