Local farmers wear poor or non-existent Saw-scaled viper.
footwear while ploughing just yards from where the snakes live.
Imagine you are manually ploughing a field in a tropical country; you feel a quick stabbing pain in your uncovered foot and notice a snake slithering away. Your foot is bleeding from two puncture wounds and is starting to swell. Before long you are in pain; your gums start bleeding, or perhaps you start struggling to breathe,
or your foot turns black and needs amputating. It’s a horrific picture, but it’s all too real for many of the two million people bitten by venomous snakes every year. Nick Casewell’s team are working to find a solution.
stonishingly, in some regions snakebite victims occupy over 70 per cent of all hospital beds, and
as many as 95,000 people die each year, even though effective treatments exist. Snakes are often viewed in a negative way. Let’s face it, this isn’t particularly surprising, considering the social stigma attached ever since their time in the Garden of Eden or living on Medusa’s head. Yet in some cultures snakes are actually worshipped, and they appear in positive contexts on the emblems of medical and pharmacy associations, which may well have been an early and appropriate masterstroke – more on this later.
Snake venoms usually differ between different species, but all are toxic mixes of proteins that are injected (usually by fangs) to incapacitate the snake’s prey. Although most snakes are technically venomous, relatively few species are dangerous to man.
Snakes will try to avoid encounters with people or display a warning signal, such as a rattlesnake’s rattle, before they bite. Unfortunately, when one feels threatened or is surprised by a person, it will often bite in self-defence, resulting in a medical emergency.
Sadly this is extremely common across the tropics. In the UK we only have one potentially dangerous snake species, which is rarely encountered. In sub-Saharan Africa and south Asia, where most snakebite deaths occur, there are many dangerous snakes, including cobras, mambas and vipers. In rural tropical regions, people’s lifestyle is dictated by poverty, so interacting with snakes is a daily occupational hazard when farming, walking or even sleeping. These encounters are often made worse because people cannot afford appropriate footwear and often work in flip-flops or even barefoot.
I recently had the opportunity to go to Senegal to collect venomous snakes for our antivenom research project – our target species were the saw-scaled vipers, a group of very small dangerous snakes which are extremely well camouflaged. We often found them hiding under rocks during the day
– by the side of roads, around agricultural fields and even in school playgrounds. On one occasion I noticed a barefoot farmer
8 PLANET EARTH Spring 2012