Snake bite anti-venoms not very effective anymore: Researchers

Scientists at the premier snake venom research centre, Haffkine Institute in Parel, have said that existing formulations of anti-venom are now taking a longer time

Scientists at the premier snake venom research centre, Haffkine Institute in Parel, have said that existing formulations of anti-venom are now taking a longer time to neutralise effects of snake bites than they did around a decade ago. While earlier, four to five doses were enough for treatment, patients now require 20-25 doses, said researchers.

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Anti-venoms, which are extracted from captive snakes, contain antibodies that neutralise the toxins. “We have observed that the anti-venoms aren’t neutralising the venom within the time span recorded earlier. It may either be because of evolution of snakes due to climatic conditions or a technical problem in production,” said Dr Nishigandha R Naik, director, Haffkine Institute.

Researchers from other parts of the country have also made the same observation. A study by Tezpur University in Assam, published in the journal Expert Review of Proteomics, states that common anti-venoms are no longer effective in snake bite cases in south India. The study pointed out that venom from kraits found in south India had proteins which anti-venoms do not recognize and neutralise.

Romulus Whitaker, herpetologist and founder of the Madras Snake Park, also agreed that the neutralising time has increased over the last 10 years. “In 1955, the first anti-venom was produced. It was much stronger than the current brands available in India. Environmental changes may be one of the causes, but we need research to establish it,” he said.

Naik said the effectiveness may be decreasing owing to a change in anti-venom at the molecular level. “In Maharashtra you find spectacled cobra while in West Bengal, you see monocled cobra. Even though these snakes belong to the same family, their molecular formation of anti-venom is different. This is why we need venom mapping of all the states,” said Naik.

A report by the Haffkine Institute showed that snake bite cases in the city increased by 66.7% – to 427 from 256 – between 2017-18 and 2018-19. The number of cases increased by 35% in the state and by 15% across India, in the same time frame.

Whitaker said this could be because of better reporting. “Snake bite cases have always been neglected. Now, with growing awareness especially among medical experts in rural areas, the number of cases reported has increased,” he said.

Haffkine Institute uses venom from four species – Indian cobra, Common krait, Russell’s viper, and Saw-scaled viper – to produce anti-venom. The institute said that it is looking at sourcing the anti-venom from more species. The Ministry of Health and Welfare has permitted the institute to collect venom from 32 snake species.