The green pit viper (Trimeresurus erythrurus) is a medically relevant snake species in northeast India. Credit: Lalmuansanga
India’s recorded 58,000 annual snakebite deaths1 is the highest in the world, yet incidences are under-reported and data from fatalities and related disabilities is not examined on a granular level. Filling these gaps might help develop effective antivenoms and reduce mortality and disability from snakebites, experts say.
The country has set an ambitious target to halve snakebite deaths and disabilities by 2030 in line with a World Health Organization (WHO) strategy. Currently, the Indian Council of Medical Research (ICMR) is gathering hospital and community-based snakebite data. “In 2017 snakebite was added back to the WHO list of neglected tropical diseases, after being struck off the list in 2013, primarily citing the lack of data in India, which has the largest proportion of deaths and disabilities,” says Jaideep Menon at Amrita Vishwa Vidyapeetham in Kerala.
Menon is leading the ICMR project-survey of the incidence, mortality, morbidity and socio-economic burden of snakebites across 14 states covering 84 million people. In India, much of the data is centred on deaths and comes from information given by observers. To obtain accurate information on incidences and plug the data gap, the survey is engaging with the community through Accredited Social Health Activists (ASHA workers).
Vast underreporting also occurs because many victims seek treatment from faith healers rather than hospitals, and those numbers are not captured in the official data, says advocacy worker, Priyanka Kadam, of the NGO Snakebite Healing & Education Society.
Kadam's analysis2 of snakebite deaths in Madhya Pradesh from 2020 to 2022 found that the state government compensation payments, made under the National Disaster Management Act, equalled US$28 million, for an average of 2,846 snakebite deaths annually, much higher than the officially reported 330 deaths, but still below the estimated 5,200 fatalities.
Heat maps of Madhya Pradesh depicting the total number of snakebite deaths compensated in each district across 2020–2021 and 2021–2022. The darker the blue colour, the greater number of compensated snakebite deaths. The districts with the highest number of payouts were Sagar and Satna. Credit: Kadam P. et al.
Understanding the epidemiology and economic burden of snakebites could improve access to polyvalent antivenoms (PAVs) treatment and also reporting of snakebites among the rural population, says Karthikeyan Vasudevan, from the Laboratory for the Conservation of Endangered Species in Hyderabad. “The available estimates are woefully inadequate and even those indicate that the actual burden is far greater than those that get access to PAV treatment,’ says Vasudevan.
Designing effective antivenoms
Current PAVs are derived from the 'big four' snakes — the spectacled cobra (Naja naja), common krait (Bungarus caeruleus), Russell’s viper (Daboia russelii), and Indian saw-scaled viper (Echis carinatus) — but they often fail against lesser-known species due to the vast diversity in venom toxins.
New research3 from the Indian Institute of Science in Bengaluru reveals that venom potency in Russell's vipers and spectacled cobras varies dramatically across their lifespans. The venom of newborn (neonatal) Russell's vipers is far more toxic than that of older individuals, specifically targeting small reptiles like lizards. As they age, their venom becomes more effective against mammals, according to co-author, Kartik Sunagar.
The potency of the spectacled cobra’s venom remains consistent throughout its life. These findings underscore the dynamic nature of venom composition in two of India’s most clinically significant snakes, adapting to different prey types at various life stages.
Researchers are exploring new antivenom solutions, including recombinant antibodies and peptide-based treatments. This year, an international team, including Sunagar, identified an antibody4 capable of neutralizing a wide range of venom toxins across various snake species. Sunagar is now testing candidate recombinant antibodies specifically against Indian snake venoms, including the Russell’s viper.
Meanwhile, a team led by Anurag Rathore, from the Indian Institute of Technology, Delhi, is developing a peptide-based treatment that is more stable and cost-effective than PAVs, potentially offering a more efficient treatment option. "It's a complex issue, mainly affecting developing countries, and unlike diseases like cancer, big companies haven't shown interest in finding solutions," says Rathore.
Efforts are also underway to shed more light on regional antivenoms. In northeast India, for instance, Robin Doley at Tezpur University is focusing on venom from locally relevant species like the banded krait, monocled cobra, and green pit viper. Doley’s research5 on banded krait suggests that including specific proteins in the immunization mixture could enhance the efficacy of existing PAVs.
“We realise now that a large number of purported Russell’s viper bites in Kerala in south India are hump-nosed pit viper bites, which are not covered by the PAVs,” says Menon.
However, improved medical infrastructure at public and community health centres is crucial to making these treatments effective. Poor storage and handling of antivenoms at public health centres often render them ineffective, according to Kadam. The sluggish procurement system for fresh stocks is also a contributor to the non-availability of snakebite treatment at the first point of contact, she says.
Advanced technologies could optimize PAV management and reduce costs, but accurate demand forecasting is essential. "The production cycle and supply chain are directly tied to knowing the number of people needing treatment in district hospitals," says Vasudevan.
