Sea snake envenomation in India: Urgent need for specific antivenom development

Epidemiology of sea snake envenomation

India’s relationship with sea snake bites dates back over 200 years, when in 1815, M’Kenzie documented what he called an ‘epidemic’ of sometimes fatal sea snake bites near Chennai after a coastal bar opened⁷. Throughout the early 1900s, medical officers recorded deaths among oyster fishers along the Madras coast and noted that coastal villages in Odisha experienced several bites yearly with a concerning 25 per cent death rate⁷. Despite these historical accounts suggesting an ongoing problem, sea snake envenomation has remained largely invisible in India’s health statistics, creating a troubling cycle where the lack of data prevents appropriate medical resources and policies from being developed.

The most vulnerable populations include traditional fishermen who handle nets and operate small boats; workers who sort and process fish catches; and tourists enjoying coastal recreation. Most bites occur during specific activities like handling fishing nets, wading in shallow waters, sorting through catches, or accidentally stepping on snakes in coastal shallows. The risk extends across India’s vast coastline, particularly in estuaries, traditional fishing communities, and mangrove ecosystems, with documented cases in Tamil Nadu, Odisha, Kerala, Maharashtra, and the Andaman and Nicobar Islands⁸.

The true scope of this problem remains hidden due to several human factors. Many fishing communities have limited access to healthcare facilities due to their remote locations, and the subtle presentation of sea snake bites often leads doctors to misdiagnose the condition. Fatalities occurring during fishing expeditions frequently go unrecorded, while many affected individuals choose traditional healers over formal medical care due to cultural preferences and accessibility. Experts believe that official statistics, where they even exist, likely capture less than one-fifth of actual cases⁹.

This cycle of neglect has dire consequences. Without accurate numbers, hospitals don’t stock proper treatments, policymakers don’t prioritise solutions, and fishermen continue working unprotected. Traditional healing methods often replace medical care in coastal villages, further hiding the problem. As India’s fishing industry grows and coastal tourism expands, more people face this invisible threat. Breaking this cycle requires recognising sea snake bites as a distinct public health emergency that’s been quietly claiming lives for generations.

Clinical manifestations and diagnostic challenges

Sea snake bites are easy to miss because they don’t look like typical snakebites. Unlike land snake bites, which cause obvious swelling and pain at the wound, sea snake bites may leave only tiny marks with little to no redness or swelling. Instead, the real danger lies interiorly as the venom primarily targets muscles, leading to severe pain, weakness, and other life-threatening complications. Within hours, victims may experience muscle stiffness, drooping eyelids, difficulty swallowing, and dark-coloured urine due to muscle breakdown. Without treatment, the condition worsens, causing paralysis, breathing failure, kidney damage, and even death².

Doctors often struggle to diagnose sea snake bites because the symptoms mimic other coastal illnesses, such as other marine envenomation or stings, fish poisoning, heatstroke etc. There is no specific diagnostic kit to detect sea snake envenomation in India, because of which healthcare professionals have to rely solely on the history given by the sufferer. Blood tests usually show extremely high muscle enzyme levels, potassium imbalances, and signs of kidney stress¹⁰, but by the time these results come in, precious treatment time may have been lost. The lack of visible bite marks means many cases go unrecognised until severe symptoms appear. This delay in diagnosis, combined with the absence of effective antivenom in India, makes sea snake envenomation a hidden but deadly threat to fishermen and coastal communities.

Sea snake specific antivenom

India faces a challenge in treating sea snake bites, as the country lacks specific sea snake antivenom despite its availability elsewhere in the world. The polyvalent anti-snake venom currently used throughout India works against terrestrial ‘Big Four’ snakes, offering minimal protection against sea snake venom¹¹. While countries like Australia has ‘CSL (Commonwealth Serum Laboratories) sea snake antivenom’ which neutralises a wide variety of sea snake venoms- including olive sea snake Aipysurus laevis, Stoke’s sea snake Astrotia stokesii, olive headed sea snake Disteira (Hydrophis) major, banded sea snake Hydrophis cyanocinctus, elegant sea snake Hydrophis elegans, Daudin’s sea snake Hydrophis nigrocinctus, narrow banded sea snake Hydrophis spiralis, Gunther’s sea snake Hydrophis stricticollis, spine-bellied sea snake Lapemis hardwickii, banded sea krait Laticauda semifasciata and needle-headed sea snake Microcephalophis gracilis¹² some of which are found in Indian waters, but these antivenoms remain unavailable to populations who need them the most. Barriers include economic disincentives for pharmaceutical companies, technical challenges in collecting sea snake venom, regulatory hurdles for importing foreign antivenoms, cold chain maintenance difficulties in remote areas, and limited awareness among healthcare decision-makers. Various challenges in management of sea snake envenomation are summarised in table.

When examining the practical implications, developing or importing sea snake antivenom would require a high initial investment, plus annual distribution costs for maintaining cold chains to coastal facilities. However, these high costs seem justified considering the potential benefits of saving several lives annually, preventing long-term disability among survivors, and preserving economic productivity that contribute significantly to coastal economies. The development of sea snake-specific antivenom for India would require: (a) comprehensive venom collection and characterisation from Indian sea snake species, (b) immunisation protocols using appropriate animal models, (c) extensive cross-reactivity testing, (d) clinical trials for safety and efficacy validation, and (e) establishment of appropriate manufacturing and distribution infrastructure.

Disparities in compensation

The compensation amount for snakebite varies significantly across different States in India, with Bihar, Uttar Pradesh, Madhya Pradesh, and Odisha all offering INR 4 lakhs, while West Bengal provides a much lower amount of INR 20,000¹³. Kerala offers INR 1 lakh for snakebite cases occurring outside forest areas, and Karnataka provides INR 2 lakhs specifically for farmers and agricultural labourers. Chhattisgarh has set compensation at INR 1.5 lakhs, and Punjab offers INR 2 lakhs to affected individuals¹³. These existing compensation policies rarely address sea snake bites specifically, creating additional challenges for affected coastal communities.