600 deaths in 10 yrs, why Kerala can't defang a small snake to achieve zero-mortality?

Snakes have killed more people than any other wild animal in the past 10 years in Kerala; 600. Even the cumulative deaths caused by elephants, tigers, wild gaurs and boars are just above 50 per cent of snake-bite fatalities; a reason why Kerala plans to eradicate snakebite-related deaths within five years or at least halve the present mortality rate in two years. The state has bigger concerns in achieving this target. It's not the mighty four - the spectacled cobra (moorkhan), the common krait (vellikettan), Russell's viper (chenathandan) or the saw-scaled viper(churutta mandali) - that make the objective hard to attain.

A small snake, the hump-nosed pit viper (HNPV), once thought to be moderately venomous, is now known to cause life-threatening complications. The worst part is that Kerala doesn't have an antivenom specifically to combat this reptile. The polyvalent anti-snake venom (ASV) is effective only against what is commonly called the Big 4 venomous species. 

"The state doesn't have an ASV for species like HNPV (muzha mookan), which is endemic to the South-Western Ghats. Most number of venomous snakebites reported in Kerala are those of HNPV and there are several deaths reported due to HNPV," shows the minutes of the meeting convened by the Kerala chief secretary as part of drafting guidelines to ensure safety in schools against snake-bite incidents.

"From Kasaragod to the southernmost part of the state, HNPV is commonly found. It prefers wet, moist surfaces. Though considered not as lethal as a cobra or a krait, this snake can inflict serious damage on an immunocompromised person or on children. We need to develop either a monovalent ASV exclusively for HNPV or a polyvalent one for other vipers like the Malabar pit viper (chola mandali) or the Bamboo pit viper (mula mandali)," said Mohammad Anwar Y, state nodal officer for snake rescue and Assistant Conservator of Forests.

Kerala forest department has been able to significantly reduce the mortality rate due to snake bites in the past five years with the help of SARPA app, an initiative that enables people to connect with the department's trained snake rescuers. 

The forest department collaborates with the Evolutionary Venomics Lab at the Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, to develop an ASV for HNPV. Kartik Sunagar, an Associate Professor at IIS, who is a renowned researcher of animal venoms, said that the work is now focused on developing region-based antivenoms. "We have developed an antivenom for a particular species of snake found in Maharashtra and Rajasthan. We need to develop region-based antivenom for Tamil Nadu, Karnataka and Kerala," Sunagar told Onmanorama.

This may still not offer a permanent solution for Kerala. "Monoclonal antibodies and small molecule inhibitors (repurposed drug combinations) could be a far effective solution for snakebites, and these are considered as alternatives to antivenom therapies," said Sunagar. 

A study titled 'Fangs in the Ghats' by Sunagar and other researchers shows that polyvalent antivenoms have therapeutic inadequacies in neutralising the local and systemic toxicity resulting from pit viper envenomings. The HNPV has been documented to impair the ability of blood to coagulate and can cause severe haemorrhagic complications in bite victims. In certain cases, the demise of the patients, as immediately as within the first thirty minutes of envenomation due to cardiac arrest, has also been reported in Sri Lanka.

According to Mohammad Anwar, there are challenges in the current medical protocol and access to ASV, which cause snake bite deaths. "Administering antivenom can also result in adverse reactions. Often, identifying the species and deciding on the course of treatment gets difficult," said Anwar. While there is obvious evidence of bites like fang puncture marks, bleeding and swelling, in some cases, like in a krait bite, no local marks would be seen. It can only be noted by a magnifying lens as a pinpoint bleeding spot with a surrounding rash. 

This is where Sunagar stresses the importance of SMIs in early intervention. He said that his team of researchers have discovered that two repurposed drugs, which previously entered phase 3 clinical trials for other uses, can prevent the lethal effects of Russell's viper. The research is also underway on developing a human monoclonal antibody for treating neurotoxic snakebites from different regions, he said.