If you leave a snake alone it will leave you alone, right? So how do 6000 people in southern Africa manage to get bitten by snakes every year?
There is a great deal of speculation about how many people are bitten annually by snakes, and one figure that is often quoted for southern Africa is 6000.
Snake lovers are quick to claim that most victims are bitten while trying to kill snakes. Others feel that the majority of victims are snake enthusiasts or keepers who get bitten while capturing or handling snakes.
Text: Johan Marais
Compared with the total number of bites, however, snake handlers make up a very small percentage of victims – probably less than 3%.
We know that the vast majority of snakebite victims are rural people who are bitten when they accidentally stand on a snake or while working their land, usually barefoot. Most bites happen on warm summer days or nights, often after rain. Most victims are bitten on the lower leg, although bites on the hands and arms also occur quite regularly.
Interestingly, the Mozambique spitting cobra accounts for most of the serious bites, but there are few fatalities.
Second on the list is the puff adder, followed by the stiletto snake. Fatal bites are quite rare, and we have never recorded a fatal bite by a stiletto.
The black mamba and Cape cobra account for most fatal bites, mainly because of their fast-acting venom, which causes progressive weakness and affects breathing.
It is common knowledge that snakes are generally quick to move off if confronted. Exceptions are the puff adder and Gabon adder, which remain very still and rely on their excellent camouflage to avoid detection. If you are 5m or more away from a snake you are perfectly safe. There is no snake in southern Africa that will approach you from 5m away and attack you – not even a black mamba.
Having said that, we are seeing more and more cases of people being bitten while asleep in their beds. This is most puzzling, and the logical explanation is that the snake enters a bed in search of warmth and when accidentally rolled on, strikes out in self defence.
It’s a nice theory, but way off the mark, I think. Firstly, in well over 95% of such cases the snake responsible is the Mozambique spitting cobra. These snakes actively hunt their prey, which consists largely of frogs, rodents and other snakes, but they eat just about anything they come across.
We know that with defensive bites, these snakes often give a quick bite without injecting venom – the so-called “dry” bites. And even when venom is injected in defensive bites, there is usually very little envenomation. But in most of the bites in beds we are seeing severe envenomation, and in many cases the victim will have received more than one bite.
These bites are inflicted on the hands, arms, body and face – even in the eyes. And although it is largely rural people who are bitten, often while asleep on the floor, there have been a number of occasions when tourists have been bitten while asleep in their beds at luxury game lodges.
It appears that the snakes are ending up in houses, either accidentally entering through the gap under perimeter doors of perhaps going into houses in search of food. Once inside a house, the snakes creep onto beds and bite people who are sleeping.
The only logical explanation (and I have debated this at length with other experts) is that the snakes mistake the victims for food and bite with intent, often more than once.
The cobra’s venom is potently cytotoxic. Victims must be hospitalised urgently and usually need anti-venom. The longer it takes to get the victim to a hospital, the worse the effects of the venom will be. The outcome could be severe necrosis, requiring surgery.
I am keen to run a series of experiments to try to establish exactly why these cobras bite sleeping people. Hopefully this research will start soon. Meanwhile, if you are in areas where these snakes occur, make sure your doors seal well and that you cannot push a finger into the gap under any outside door. If your finger fits under the door, a snake would be able to squeeze through.