With at least 100,000 fatalities per year, the venomous snake bite is a major and underexposed problem

But Dutch researchers, among others, are working hard on a solution.

You can regularly read in the newspaper that people are being attacked by sharks. And crocodiles that kill people can also count on the necessary media attention. Much less often, however, you hear about people dying after being attacked by a venomous snake. And that while that occurs many times more often than, for example, a deadly shark bite. “Every year, an average of 100,000-150,000 people die after being bitten by a venomous snake,” explains Mátyás Bittenbinder, biologist and toxicologist at Naturalis (Biodiversity Center in Leiden) and the Free University (Amsterdam). “However, the true number of fatal snakebites is likely much higher, as many deaths go unrecorded. It is a problem of poor countries in Sub-Saharan Africa, Southeast Asia and Latin America. The victims are often farmers and herders who have no or limited access to medical care and who turn to their local medicine man with complaints. When they subsequently die, their death is not recorded.”

Survivors

In addition to the at least 100,000 people who are killed by the bite of a venomous snake, there are also an estimated 500,000 people each year who survive the bite of a venomous snake, but are left with permanent damage. “Blindness, muscle damage, joint pain, ulcers, kidney and liver disease,” Bittenbinder lists. “And sometimes body parts have to be amputated. It has a huge impact on the victims who often have a physical profession.” Because work is difficult or even impossible, they end up in poverty.

Dangerous snake species

Worldwide we are aware of about 3800 different snake species. 750 of these are considered poisonous. “And 250 of those are labeled as ‘medically relevant’ by the World Health Organization. That basically means that they often collide with people and also carry a dangerous poison.” Ultimately, however, only a handful of species are responsible for the large number of fatalities that occur each year. “For example, in India – which has the highest number of deaths with 50,000 deaths – only five snake species are responsible for virtually all snakebite-related deaths.” One of those species is the at first sight not even very impressive saw-scaled badger. “A small snake actually; as thick as a thumb and as long as a forearm.” But extremely poisonous. “The venom affects blood clotting and makes the victim’s blood thinner. At the same time, the poison also causes holes in the blood vessels. That leads to internal bleeding.”

saw scales. Image: Mvshreeram (via Wikimedia Commons).

Another snake species that makes many victims in India is the Indian cobra. “This one is also called the spectacled snake, because of the spectacle-shaped drawing on its hat. This snake’s venom is neurotoxic, meaning it affects nerve transmission and nerve endings. This shuts down the muscles and causes problems with breathing, for example.”

Indian cobra. Here you are looking at the back of the hat, with the glasses-like drawing on it. Image: Ganesh SahSudi (via Wikimedia Commons).

The Russell’s viper also claims many lives in India. “The venom of this viper breaks down the muscles. This releases molecules that cannot be broken down by the kidneys. It results in kidney failure and most victims die within 24 to 48 hours.”

Russell’s viper. Image: Davidvraju (via Wikimedia Commons).

Africa

Also in Africa, venomous snakes claim many lives every year. In addition to the saw-scaled cobra, which we briefly introduced above, the Mozambican spitting cobra is also notorious. Unlike many other venomous snakes, which inject the venom into their skin through their teeth and therefore have to make direct contact with their victim, the Mozambican spitting cobra can strike from a distance. “Well, from two or three meters away,” says Bittenbinder. As the name suggests, the cobra spits venom. “And when that gets in the eyes, the victim can go blind.” Another very dangerous snake that regularly strikes in Africa is the black mamba. “This snake is also equipped with a neurotoxic venom that causes respiratory problems.”

Differ

And so there are hundreds of other poisonous snakes, but they are not all equally dangerous. Some species are more poisonous than others. “In addition, the amount of poison that is injected is also decisive.” How long it then takes for people to develop the first serious health problems also differs. “You often see that within 2 to 3 hours after the bite, minor complaints arise, such as swelling at the site of the bite and a metallic taste in the mouth. Life-threatening effects often develop later. In the case of Russell’s viper, for example, only after 24 to 48 hours.” It’s different after a bite from the black mamba. “Victims can feel the first effects within half an hour and some die within two hours.”

Antidote

There are not many options after a bite from a venomous snake bite. “Right now there is only one option and that is antidote. That antivenom is obtained by administering small amounts of snake venom to horses or sheep. Because it concerns small amounts, they don’t get sick from it, but their body does make antibodies against the poison. After a few months, blood is taken from the horses and sheep, the antibodies are filtered out and that is the antidote.” Although such an antidote – if administered in a timely manner – is effective, it also has a number of drawbacks. “Because every snake has a unique venom cocktail, you also have to develop its own antivenom for each snake species.” In addition, the production of the antidote is quite time-consuming and labour-intensive. Another drawback is that the resulting antidote must be kept cool. And that is often difficult in poorer, remote areas where venomous snakes often strike.

Alternative to Antidote

But there is hope. Scientists – including Bittenbinder and professor Freek Vonk – are working hard on an alternative to the traditional antidote. “We use so-called small molecule inhibitors, these have been developed as medicines and already approved by the FDA (American Food and Drug Administration, ed.).” But Bittenbinder and colleagues use them for very different purposes. “We ensure that the small molecule inhibitors target a toxin group in venom. For example, toxin group A, B or C. Each venomous snake species has its own venom cocktail, but those different toxin groups are reflected in the venom of most snakes. If we have the small molecule inhibitors can combine each targeting a different toxin group, there could be a single agent that takes care of all the toxins that are present in all snake venoms and with which all those venoms can also be combated.” Work is already underway on such a universal panacea. “We hope to complete it within ten years,” says Bittenbinder, who emphasizes that its production is also much cheaper than that of the traditional antidote. “In addition, the drug can be stored at room temperature.”

Procedure

It almost sounds too good to be true. And that’s what it is at the moment. Because there is still a lot of work to be done. “First of all, it is important that we better understand snake venom and its effects. We also need to test whether it is possible to use combinations of small molecule inhibitors and whether those combinations are also safe.” However, Bittenbinder expects the biggest challenge at the end of this still long research process. “Then we have to convince people that this drug is reliable. And that can be difficult, because they often blindly rely on their medicine man.”

However, scientists will do everything they can to ensure that the drug gets there and is embraced by the people who need it so much. Because that high number of deaths from poisonous snakebites must be reduced. “The aim of the entire community is to halve the number of people killed by venomous snake bites by 2030,” Bittenbinder said. “That is ambitious, but we hope that we can really make a big difference with this small panacea.”