A slither of DNA identifies snakebite antidote

Bitten by a snake? A DNA test could help find the antidote. When a snake bites someone, it leaves some of its DNA along with the venom. Now, that can identify the species of snake; a finding that could take the guesswork out of choosing the right antidote.

"At present, the standard of practice is no identification at all, a diagnosis from the symptoms, or more rarely identification of dead snakes that victims occasionally bring to the clinic," says François Chappuis of Geneva University Hospitals in Switzerland, who presented the work this week at the American Society of Tropical Medicine and Hygiene annual meeting in New Orleans.

Chappuis and his colleagues collected samples from the fang wounds of 749 people at three health centres in Nepal, amplified the DNA and sequenced it. They then looked for matches in a publicly available reference bank of DNA sequences. They managed to identify the snake species responsible for 194 bites, 87 of which were from species whose venom is harmful to people – most commonly the spectacled cobra and the common krait.

The earlier the culprit species can be identified, the sooner the correct antidote can be given. Chappuis says his team's ultimate aim is to produce simple bedside tests that change colour in around 30 minutes to indicate if a local venomous species appears to be responsible for a bite.