The first effective remedy for the bite of a spitting cobra has been found

Scientists have discovered a new treatment for snake bites that prevents tissue destruction caused by the venom of the African spitting cobra.

The venom of a spitting cobra is extremely powerful and causes dermonecrosis, which manifests itself in the rapid destruction of the skin, muscles and bones around the bite site. This can lead to permanent injury and disfigurement, including loss of limbs and amputation in extreme cases.

Professor Nicholas Caswell and his colleagues from the Liverpool School of Tropical Medicine, including Dr Steven Hall, now at Lancaster University, have found that using a repurposed drug varespladib to block one of the two main toxins causing dermonecrosis in spitting cobra venom prevents damage to skin and muscles.

Snake bites cause long-term adverse effects in about 400,000 people worldwide each year, with a significant proportion of these cases in Africa attributed to spitting cobra bites.

There is currently no effective treatment to combat severe local poisoning caused by spitting cobra venom. Existing antitoxins only work against bites from other species of snakes and are often ineffective in treating local envenomation because the antitoxin antibodies are too large to penetrate the area around the bite site.

Professor Caswell said: "Our results promise to significantly improve the treatment of snakebites in tropical regions. Current treatments for spitting cobra bites are widely recognized as ineffective, leading to high rates of disability and amputation in much of Africa. Our data shows that blocking only one of the major families of toxins in spitting cobra venom will likely prevent the tissue destruction that affects thousands of patients each year."

Professor Caswell's team, led by PhD student Keira Bartlett and Dr Steven Hall, as well as researchers from Canada, Denmark, Costa Rica and the US, first analyzed the venom of the spitting cobra to identify the toxins that cause dermonecrosis. The results showed that cytotoxic three-finger toxins (CTx) are the main culprits, but phospholipases A2 (PLA2) also play an important role in this process.

Topical administration of the PLA2 inhibitor drug varespladib reduced the severity of dermonecrosis, even when given one hour after the bite, and the protection provided by the drug also extended to venom-induced muscle toxicity.

The study results suggest that varespladib may be a valuable treatment against tissue damage caused by the venom of black-necked and red spitting cobras, which cause significant suffering in snakebite victims across the African continent, the authors said.

Lead author Dr Hall said: “Snakebite is a devastating neglected tropical disease in which tissue necrosis caused by venoms causes permanent injury to hundreds of thousands of victims each year. "

"Our work shows that the drug warespladib is extremely effective in inhibiting necrosis caused by African spitting cobras. This is especially important as their venoms act very quickly and destructively. We hope this research will pave the way for future therapies for snakebites, which can save the lives and limbs of victims around the world."

PhD student Keira Bartlett added: “These results are very promising; not only because this is a new treatment where there was nothing previously effective, but also because varespladib has already been tested in human clinical trials, including trials in snakebites., and may soon be available to real patients."

Professor Caswell's team is already looking for viable treatments that effectively block CTx toxins. Having treatment against both toxins could significantly increase the effectiveness of varespladib and significantly reduce the long-term consequences associated with spitting cobra bites in Africa and beyond.

The research results were published in the journal Proceedings of the National Academy of Sciences.