What happens when you get bitten by a snake?

Note: This piece contains images and video of snakes

Snakebite is one of the world’s deadliest neglected diseases. It is thought that one person dies from a snake bite roughly every 4 minutes.

The World Health Organization estimates that 5.4 million people are bitten by snakes each year. Of these, 80,000 to 140,000 people die. Three times as many sustain long-term disabilities, including as a result of amputation. However, these figures are believed to be a serious underestimate.

What is snake venom and what does it do to you?

A snake’s venom contains a mixture of toxic chemicals which are injected into the body during a bite. That’s the difference between venomous and poisonous: venomous things can harm you if they bite you; poisonous things can harm you if you bite them. (In the 17th century, an English doctor called Richard Mead drank viper venom to prove it was venomous, not poisonous.)

Exactly what a particular venom does to the body depends partly on where the snake normally finds their dinner. Snakes mostly use their venom to kill or immobilise prey, although they also sometimes bite defensively when they feel under attack – especially from humans.

Snake venoms can cause paralysis, bleeding, kidney failure and tissue damage. There are three main categories: cytotoxic, neurotoxic and haemotoxic.

Cytotoxic venoms

Snakes that are able to track their next meal for long distances across the desert might need to only slow a rodent or lizard down enough to be able to catch up with them. Those snakes will likely produce venom that acts on the cells or the blood – cytotoxic or haemotoxic – which causes tissue to die and blood to stop clotting.

Humans bitten by these types of snakes can develop gruesome wounds as the venom eats away their skin and bone. They may lose the use of limbs or require amputation. This can mean not only living with pain and loss of mobility, but often suffering a loss of livelihood too. Subsistence farmers become unable to produce food for their families. Loss of earnings mean children can no longer be sent to school.

Neurotoxic venoms

A snake found in rocky mountains, on the other hand, where there are lots of cracks and holes for a tasty mouse to disappear into, will want to produce venom that can paralyse very quickly.

Some of the world’s most deadly snakes to humans, including the African black mamba, produce neurotoxic venom that does just this. The venom blocks nerve signals travelling to your muscles, including the ones that help to inflate and deflate your lungs allowing you to breathe. Victims can die within an hour of being bitten.

Haemotoxic venoms

Vipers, which are found across mountains, forests and deserts, usually have haemotoxic venoms which can kill prey quickly by causing stroke or massive internal bleeding. In the case of human bite victims, several hours after a bite, these venoms stop the blood from clotting and send their victims into shock. Those bitten will often bleed copiously from the wound and from their nose and mouth, as well as suffering internal bleeding.

If this goes untreated, it can kill or cause lasting organ damage. This could require long-term medical care that patients may not be able to afford.

What should I do if I get bitten by a snake?

Antivenom is the only evidence-based treatment currently available for venomous snake bites, but the longer you wait, the less likely it is to work, so you need to get medical help quickly.

But, as the Bureau of Investigative Journalism has found, there are many things standing in the way of people receiving good treatment. It’s estimated only a small fraction of people bitten by venomous snakes have access to quality antivenom.

What shouldn’t I do if I get bitten by a snake?

We can’t give medical advice, but the NHS’s travel advice page advises not to cut, rub, wash or burn the bite or attempt to suck out the venom – and to turn down offers of “traditional” healing techniques.

Visiting traditional healers can delay people being given antivenom, raising the risk of death or serious injury.

Why don’t we have accurate numbers for snakebite?

The reality is, many snake bite injuries go unrecorded. The most affected are the poorest people living in rural areas. Farmers, women and children are especially vulnerable. The figures we have are largely based on hospital records, but the people most likely to get hurt or killed often don’t make it to a hospital.

In the studies that have taken place in communities – where a researcher goes around systematically asking people whether they have been bitten by a snake in the previous year for example – the numbers are much higher. Studies carried out in Sri Lanka and Mozambique found about 60% of snake bite cases did not show up in the hospital statistics.

Many people across sub-Saharan Africa go to traditional healers instead of, or before, hospital-based care. That might be because the hospital is further away, more expensive or considered less trustworthy.

A lot of death and injury could be prevented if all snakebite victims had quick access to treatment. But a feedback loop has set in: a lack of good, affordable antivenom puts people off going to hospital to seek it out. This makes the number of recorded cases look smaller than they really are, which in turn may reduce the pressure for people spending healthcare dollars to tackle the problem.