Biomedical-research funder the Wellcome Trust has announced an ambitious initiative to improve the treatment of snakebites in poor countries. Snakebites kill tens of thousands of people a year, partly because they are treated with archaic antivenoms that often work only for one species.
Wellcome’s £80-million (US$103-million) programme, announced on 16 May, aims to improve existing therapies and will also support the development of antivenoms that can treat the toxins of different snake species.
“After many years of neglect, the tragic global threat of snakebite is fortunately now receiving significantly greater attention,” says Mark Feinberg, president of the International AIDS Vaccine Initiative, which also supports research into snakebite treatments.
Snakebites are a daily concern in many tropical and sub-tropical regions. The World Health Organization (WHO), which is due to publish a strategy on snakebite on 23 May, estimates that between 81,000 and 138,000 people die from snakebites each year. People in rural areas in sub-Saharan Africa and India who have limited access to hospitals and medication are most at risk.
Snakebites have historically received little attention from researchers and policymakers, and few new treatments have been developed. Existing antivenoms rely on antibodies made by injecting large animals such as horses with small amounts of snake venom. They must also be refrigerated and administered by intravenous injection or infusion under the supervision of a doctor, making treatment in the field difficult.
High-quality antivenoms are also expensive to make, often work only against the species of snake from which the venom was taken and can cause dangerous side effects, such as potentially fatal allergic reactions. In sub-Saharan Africa, a hotspot of the snakebite crisis, the drugs are in short supply — and even when hospitals have them, they are often ineffective against local snake species.
Wellcome — together with medical charity Médecins Sans Frontières (also known as Doctors Without Borders) and local partners — plans to establish a pan-African network of clinical trials carefully designed to test promising new drug candidates in people, says Phillip Price, who leads snakebite science at the Wellcome Trust in London.
From horses to humans
Tools of genomics, immunology and structural biology promise to deliver much more effective treatments than those currently available, says Feinberg. Scientists have already discovered that certain molecules inhibit the toxic activity of venom from carpet vipers (Echis ocellatus) in Cameroon and Ghana. Other approaches rely on mixtures of certain human antibodies that can neutralize neurotoxins of the extremely venomous black mamba (Dendroaspis polylepis).
Synthetic biology also offers hope. Antivenoms based on human antibodies can be produced at roughly the same costs as animal-derived antivenoms, says Andreas Laustsen, a biotechnologist at the Technical University of Denmark in Lyngby. “We need to find antibodies that neutralize toxins in the venom of a great variety of snakes,” he says. “Here’s a real research need that Wellcome could address.”
Other research efforts under way focus on developing drugs that people could take in the field right after a bite. Such medicines, some of which are being developed at Ophirex, a company in Corte Madera, California, would be a breakthrough, says Price.
The firm hopes to start a clinical trial in New Guinea next year. Snakebites in that country are predominately from taipan (Oxyuranus scutellatus), whose venom causes general or respiratory paralysis. Being able to reliably test new drugs in African countries, which host a large variety of endemic venomous snakes, would be immense progress, says Ophirex chief scientist Matthew Lewin. Wellcome’s coordinated programme could bring rigour to these complex international projects, he says.