Snakebites are ‘neglected’ health crisis in Africa

Snakebites kill tens of thousands of Africans a year. Now, an antivenom shortage is spurring global experts to collaborate on treatment and prevention.

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Flicking its forked tongue, a bush viper in the Democratic Republic of the Congo sniffs its surroundings. A bite from these small arboreal snakes, which inhabit the tropical regions of Africa, can cause renal failure, external and internal bleeding severe enough to lead to anemia, and sometimes death.

Simon Isolomo woke at around 5 a.m., said goodbye to his wife and seven children, and hopped into his dugout canoe. That day, a Tuesday in December 2018, had begun like many others in Isolomo’s 30 years of fishing in the province of Équateur, in the Democratic Republic of the Congo. Paddling on the Likelemba River toward his fishing camp with a couple of friends, Isolomo, 52, snacked on kwanga, a popular manioc dish, and enjoyed the cool morning air.

After three hours, they arrived at the camp, and Isolomo began checking his fishing lines. Feeling resistance on one, he thrust his hand into the murky water. A sharp pain sent him reeling. Blood oozed from two puncture wounds. Just below the surface, a yellowish snake with black rings slithered from view.

With Isolomo lying in the dugout, his companions paddled frantically back to their village of Iteli. By then, he was slipping in and out of consciousness. His wife, Marie, joined the group, and they set out immediately for the hospital in Mbandaka, the provincial capital. But before they arrived, Isolomo stopped breathing and died.

Stories like Isolomo’s are all too common. Globally, as many as 138,000 people succumb to snakebites each year, according to the World Health Organization (WHO), and the vast majority of those deaths occur in developing nations. Another 400,000 people survive with amputated limbs and other permanent disabilities. In fact, snakebites claim more lives than the combined total of all other “neglected tropical diseases” listed by the WHO—rabies, dengue fever, leprosy, trachoma, among others that disproportionately affect the world’s poorest people and receive the least funding and research investment.

Nowhere is the snakebite problem worse than in sub-Saharan Africa, where some experts believe the yearly death toll may be as high as 50,000 people—more than double the WHO’s estimate of 20,000. A major factor in that toll is an acute shortage of, and limited access to, the only medicine that can neutralize the toxins of almost its dangerous snakes: antivenoms. Complicating matters is the fact that many victims, for lack of money, transportation, or distrust of western medicine, don’t go to hospitals, and staff at many health centers are insufficiently trained to treat snakebites.

To draw attention to the snakebite crisis, and to attract funding for research and treatment, in 2017, the WHO added envenomation—poisoning by snake venom—to the roster of neglected tropical diseases.

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Patients and their relatives wait to enter the envenomation treatment center at the Institute for Applied Biological Research, one of the few facilities in Africa with deep expertise in treating snakebites. But even here, electricity is sporadic, and medical supplies are rudimentary.

In 2019, the organization released its strategy for snakebite prevention and control, setting a worldwide goal to slash by 50 percent the number of yearly deaths and cases of disability from envenomation by 2030—an undertaking estimated to require nearly $140 million. (As part of the program’s pilot phase last year, the WHO allocated almost $9 million to snakebite research, treatment, and prevention.)

Elevating snakebite to this level of concern “will hopefully serve as a shock to health ministers” in Africa, says Baldé Mamadou Cellou. Cellou, 64, is a Guinean biologist and research director at the Institute for Applied Biological Research, in Kindia, Guinea, a disease research center with a snakebite clinic.

Race against the clock

The venom of elapids, a family of snakes that includes mambas and cobras, can kill within hours. It contains neurotoxins that paralyze muscles, which can lead to respiratory arrest. The venom of vipers—including puff adders and carpet vipers, which kill more people in Africa than any other snake—destroys red blood cells and causes inflammation, bleeding, and tissue necrosis. Viper bites, which may take several days to kill, are more common because these snakes are ambush predators that sit motionless for hours, making it easy for people to step on them accidentally. (Learn more: What’s the most venomous snake in the world?)

Most African snakebite victims are poor farmers or their children who work in remote fields. Once a venomous snake strikes, a race against the clock begins. Transporting someone who’s been bitten to the nearest hospital may take several hours, as in the case of Isolomo, or even days. By then it may be too late.

Once a patient arrives at a treatment center, two vital questions must be answered: Is a reliable antivenom available? And if so, does the medical staff know how to administer it while also treating the potential side effects, which can range from nausea and vomiting to potentially lethal anaphylactic shock? Often, the answer to both is no.

Many African snakebite victims aren’t taken to a hospital. Families often seek help from a traditional healer, who may apply leaves or ash from burned animal bones or tie tourniquets around bitten limbs, which can dangerously restrict blood flow and oxygenation of the muscles. Some locally available plants do mask pain and reduce swelling, but they can’t save a victim’s life, Cellou says.

Snakebite survivors may credit traditional healers with saving their lives nonetheless. That’s because about half of snakebites are dry, with no venom injected, says Eugene Erulu, a physician at Watamu Hospital, in southern Kenya. “So the patient is convinced that the healer saved them,” he says, “even though there was no envenomation in the first place.”

The roots of a remedy

Cellou, now a world-renowned lecturer on snakebites, began studying snake envenomation 25 years ago. A 12-year-old girl who’d been bitten showed up at the Institute for Applied Biological Research, where he was working as an entomologist, and no one knew how to help her. The institute had been a bustling snakebite treatment center in the early 1900s, but by mid-century its focus had shifted to hemorrhagic fevers.

“These people were being given up on,” Cellou remembers thinking. After the girl died in his arms, he vowed that she would be the last such victim. He stopped studying insects and turned his focus to how best to treat snake envenomation.

In his search for snakebite treatments, Cellou has experimented with Chinese-made pills and inexpensive injections of Indian-made antivenom he bought in village markets. He also relied on Fav-Afrique, an antivenom made by the French company Sanofi that’s effective against the bites of about 10 snakes, including carpet vipers, mambas, and cobras. But in 2015, Sanofi announced it had discontinued production because the medicine wasn’t profitable.

Producing antivenom is a long, expensive process. Pharmaceutical companies must buy venom from labs that extract it from snakes kept in captivity. Depending on the species, venom can cost from a few hundred to several thousand dollars a gram. Venom in small amounts is injected into horses, the animal of choice because they’re easy to breed and have a large amount of blood. The horses slowly develop antibodies. Antibodies are then extracted from their blood and purified to make antivenom in liquid or powder form.

Most antivenoms are developed to neutralize the venom of a single snake species—a challenge because the chemical makeup of venom can vary from snake to snake in a single species and even among snakes hatched from the same egg clutch. “There’s a huge lack of published data and research on this,” says Jordan Benjamin, founder of the U.S.-based Asclepius Snakebite Foundation, which provides supplies and training to African health centers. Furthermore, individuals react to snakebites in unique ways, making treatment “part science and part art,” he says.

“Sometimes antivenoms that are supposed to treat certain [snake] species don’t even work in some areas,” says Colorado-based medical toxicologist Nick Brandehoff, the foundation’s medical director. For example, “the puff adder’s venom can change from one area to another. It’s extremely complicated.”

Developing an antivenom that treats multiple species is especially difficult, which is why the loss of Fav-Afrique had health care providers so worried.

A game changer

By 2013, a company in Mexico, Inosan Biopharma, had, with help from Cellou and other experts, perfected Inoserp Pan-Africa, an antivenom that neutralizes the toxins of at least 18 snake species—more than any other antivenom available in Africa. (Learn more about a promising multispecies antivenom for Asian snake species.)

“Inoserp’s broad coverage of species means that you can use it even if you’re not sure which snake bit the victim,” Benjamin says. “And it has an extremely low rate of severe side effects, which is a common problem with other antivenoms.”

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Nabi Camara checks thickets and bushes for snakes in western Guinea’s forest-savanna habitat. A snake catcher at the Institute for Applied Biological Research, in Guinea, Camara lost his left index finger to amputation after he was bitten by a western green mamba.

Another advantage: Unlike liquid antivenoms, which must be kept cold, Inoserp comes in a freeze-dried formulation. That it doesn’t need to be refrigerated is “a game changer,” Cellou says, “as in most of rural Africa, we constantly struggle with power cuts.”

Experts agree that Inoserp has been a leap forward for tropical medicine. At his institute, Cellou says, snakebite mortality was 18 percent during the 1990s. By 2019, thanks largely to Inoserp Pan-Africa, it had plummeted to 1.3 percent. Now, he says, “the only [institute] patients who die come from far away—they arrive too late.”

For all its effectiveness, there’s a severe shortage of this medicine: Laboratories produce less than 5 percent of the two million vials needed every year in sub-Saharan Africa. And even if Inoserp was widely available, rural Africans—whose earnings may be no more than a few dollars a day—couldn’t afford it. Hospitals charge between $80 and $120 a vial, and most snakebite victims require several vials. (Read about the challenges of treating snakebites in the Amazon.)

Cheaper antivenoms are available, but they’re made by laboratories that may not follow international quality control standards and are often unreliable. “In several African countries, we came across antivenom designed to treat bites from Indian snakes,” says Jean-Philippe Chippaux, an expert in tropical diseases at the Paris-based French Research Institute for Development. Chippaux helped write the WHO’s snakebite strategy and contributed to the development of Inoserp. Meanwhile, mistakes made in treating snakebite victims, such as using the wrong antivenom or an inadequate amount, reinforce rural Africans’ bedrock distrust of health care professionals.

‘Make antivenom cheaper’

A 2016 study led by Chippaux showed that while properly treating a snakebite is expensive, lost worker productivity—from disability or death—can be even more costly. “Governments should offer financial support,” Chippaux says. “They should make antivenom cheaper so that people can be treated.”

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A puff adder, which inflates its body and hisses to warn potential aggressors, basks on warm rocks in western Guinea. Ranging widely through Africa, this species ranks among the continent’s top five deadliest snakes—its bite ravages living tissue.

Inosan Biopharma is investing millions of dollars to ramp up production of Inoserp in Mexico, hoping that African governments will eventually commit to buying sufficient amounts to counter the snakebite crisis. “So far, we’re not making a profit on Inoserp,” says CEO Juan Silanes. “We see [this] as the investment stage, but we’re proud of what we’re doing because it’s an important cause.”

Other companies in other nations are also researching new treatments, and some philanthropic organizations are stepping in where government support lags. Asclepius, for example, provides free Inoserp and medical training to health centers in Guinea, Kenya, Sierra Leone, and the Republic of the Congo. The James Ashe Antivenom Trust buys antivenom for hospitals in Kenya’s Kilifi County so patients can get free treatment. If such programs are widely replicated and publicized, the thinking goes, more victims would seek immediate hospital treatment rather than turn to traditional healers.

But, as Cellou says, preventing snakebites is better than having to have to treat them. To this end, educators from the Centre Antivenimeux, based at the University of Kinshasa, visit rural Congolese communities to train doctors, teach villagers how to identify venomous snakes—and dissuade them from killing snakes, which can lead to fatal bites. People are encouraged to wear shoes when walking in places likely to have snakes and to use a flashlight at night.

“Snakebite being a disease of the poor, our policymakers always had a tendency to ignore it,” says Watamu Hospital’s Eugene Erulu. But he hopes the WHO’s new global investment in snakebite prevention will be effective. “Now our governments are going to be forced to look at it as a serious problem,” he says. “This is a very, very important step.”

Thomas Nicolon is a photojournalist and National Geographic explorer who covers wildlife conservation, among other environmental issues. Over the past few years, he has focused on conservation in conflict zones in Central Africa. Follow him on Instagram and Twitter .
This story was produced with support from the National Geographic Society.