Researchers at the Liverpool School of Tropical Medicine (LSTM) are working to develop a universal antivenom to treat victims of any of the most venomous snakes in sub-Saharan Africa.

Venom extraction, photographed by Kalyan Varma. Licensed under GFDL 1.2 via Wikimedia Commons.

The antivenom could prevent many of the 32,000 deaths from snakebites in sub-Saharan Africa each year and help cut the number of people left permanently disabled, which stands at 96,000 a year.

The researchers, who have been awarded Medical Research Council (MRC) funding, hope to develop an antivenom that can be stored safely at ambient temperature, avoiding the need for refrigeration.

Project lead Robert Harrison has collected 21 species of Africa’s most venomous snakes – 450 animals in total – which will be milked to prepare the treatment.

In countries such as the UK, which have only one species of venomous snake, snakebite victims can normally be given species-specific antivenom, offering safe and effective treatment. However, in rural areas of sub-Saharan Africa the situation is far more challenging.

Dr Harrison, who is head of LSTM’s Alistair Reid Venom Research Unit, said: “There are more than 20 species of deadly snakes in sub-Saharan Africa and doctors often rely on the victim’s description of the animal to help them decide which treatment to administer.

“The preferred option, therefore, is to give a broad-spectrum, or poly-specific, antivenom to cover all the possible snake species that could be responsible.

“Because these treatments are generally not very effective against any one species, the doctor administers many vials. However, each dose carries a risk of serious side effects, and this risk increases with each additional vial.”

The current need to give many vials also often makes treatment unaffordable to the impoverished subsistence farmers that are at greatest risk.

The limitations of current multi-species antivenoms arise from the process used to make them. Venom is milked from several species of snake before being injected in low doses into horses or sheep.

While this doesn’t cause illness in the animals, the venom induces an immune response and the animals produce antibodies. These antibodies are then purified from the blood to create antivenom. Using multiple snake species, however, means the animals make only a small amount of antibody to any one species, and the resulting antivenom is quite weak.

The research team at LSTM, along with their collaborators at the Instituto Clodomiro Picado in San José, Costa Rica and the Instituto de Biomedicina de Valencia in Spain, have devised a plan to vastly improve the potency of poly-specific antivenom using a pioneering new technique called antivenomics, which will significantly expand the effectiveness of the antivenom to cover all the most medically-important snakes of sub-Saharan Africa.

The need to refrigerate antivenom throughout the manufacturing process and in storage also severely limits its availability in rural-remote African hospitals. To overcome this, Dr Harrison’s team plans to test a series of special molecules added to the antivenom during manufacture to increase its stability at ambient temperatures.

The antivenom will be manufactured using a system developed in Costa Rica, which is considerably cheaper than most antivenom manufacturers, reducing costs by up to three-quarters and making it affordable to rural African communities.

Dr Harrison added: “Snakebite has often fallen outside the tropical infections remit of many international funding agencies.MRC support, therefore, represents important recognition that snakebite is a very serious public health concern to some of the world’s most impoverished communities.

“It also, magnificently, provides us with the opportunity of using novel scientific techniques to develop an antivenom for sub-Saharan Africa that should be unparalleled in its effectiveness, safety, storage and affordability to those rural African snakebite victims that need it the most.”

Paul Moss, chairman of the MRC’s Infections and Immunity Board, which is funding the work, said snakebite hit people living in the poorest communities the hardest.

“Addressing such health inequalities is a core part of the MRC’s mission,” Prof Moss said.

“Snakebite, while serious, is a perfectly treatable condition given the right tools, which this innovative project promises to deliver in the form of an affordable treatment that works even for those living in the most challenging circumstances.”

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