Commercial antivenom for the one of the most poisonous snakes in the world, the Russell’s viper, may not be as effective for populations in North India. The venom itself showed dramatic differences in composition and toxicity based on geographical location, according to researchers at the Centre for Ecological Sciences (CES) at the Indian Institute of Science and collaborators.
The findings of the research team were published in the peer-reviewed journal PLoS Neglected Tropical Diseases on March 25. In a press release, IISc stated the team also found that “commercial antivenom treatment for Russell’s viper venom works as marketed for most populations, except the North Indian populations.”
According to researchers, these latest findings are in contrast to a 2021 study on Indian spectacled cobras, which, while showing a similar variation in the reptile’s venom based on its location, found that commercial antivenom treatment was not effective against most populations.
Antivenom comprises antibodies that bind to the toxins in the venom and neutralise them. Snake venom, however, is known to be adaptive depending on the environment. To understand the actual efficacy of antivenom against Russell’s viper venom in the latest study, researchers collected venom from 48 vipers in five biogeographical regions of India, as well as tested how well the antivenom neutralised the different types of venoms in mice.
“Surprisingly, despite the variations in venom composition, commercially available antivenom worked as marketed for most populations, except for those from the semi-arid region of Northern India. However, these experiments do not indicate whether the antivenom also offers protection against life-long injuries that accompany Russell’s viper bites,” said IISc in the release.
Kartik Sunagar, Assistant Professor at CES, who was part of the research team for both studies, explained in the press release that even the antibody-toxin binding process as seen in lab experimentsis not sufficient to predict whether the same outcome will be replicated when administered to a human being. “Commercial antivenoms are often deployed in the market without preclinical assessments, which are typically done using animals, or clinical studies, which involve testing on humans,” stated the release.
This could explain why commercial antivenom treatment for snakebite does not always prove effective.
Tacking ineffectiveness in antivenom
Citing both the viper and cobra studies, Prof. Sunagar said, “We show that you cannot really predict the clinical or preclinical outcomes just by observing venom variation across populations. Instead, clinical and preclinical studies are the only methods to accurately test the effectiveness of commercial antivenoms.”
He further noted in the release that the results of these studies, along with older published research work, showed the preclinical ineffectiveness of commercial antivenoms in neutralising the venoms of the North Indian populations of three of the ‘big four’ snakes. The big four are some of the deadliest snakes in India: Russell’s viper, spectacled cobra, common krait and saw-scaled viper.
The answer to more efficient solutions that could save lives is in the production of region-specific antivenoms for deadly snakes in snakebite hotspots of the country, said the release. “As a long-term strategy, with the availability of enough information regarding all venom types, the team suggests developing an antivenom effective across India that would be evaluated by clinical trials”.
