Study busts myths around king cobra venom

Photo by Kalyan Varma.

  • King cobra venom is as potent as the spectacled cobra venom but of less complex composition, finds a new study from the Western Ghats.
  • Antivenoms in the market are ineffective in neutralising king cobra venom, the study reports.
  • Scientists propose manufacturing small batches of king cobra monovalent venom to protect vulnerable populations from fatalities.

King cobra venom is less complex in its composition than the spectacled cobra venom, potentially due to the strict snakes-only diet the king cobra follows, finds a new study. The study, however, warns that despite its apparent simplicity, the king cobra venom is as potent as the spectacled cobra venom. The study busts a commonly-held belief that king cobra yields a high amount of venom to compensate for its lack of potency. Moreover, no antivenom available in the market currently is capable of neutralising the venom of king cobra in South India, where the study was conducted.

India is notoriously famous for the number of deaths from snakebites, averaging to about 58000 a year, as per a study. Venom and antivenom research in India are focussed on the “big four” — the spectacled cobra (Naja naja), common krait (Bungarus caeruleus), Russell’s viper (Daboia russelii) and saw-scaled viper (Echis carinatus) that are responsible for most of the snakebite deaths. Many other venomous snakes, including the king cobra (Ophiophagus hannah), collectively referred to as the “neglected many”, are overlooked resulting in antivenoms being ineffective in treating their bites, a previous study found.

Understanding venom ecology for effective antivenom

Due to increased reporting of king cobra bites and anticipating threats to zoo keepers, herpetologists and snake rescuers, there was a need to understand the venom composition of king cobra to produce effective antivenom, said Gerry Martin of the conservation organisation, The Liana Trust, in Karnataka, who was a part of the study.

A king cobra in the western ghats. Photo by Gerry Martin
A king cobra in the Western Ghats. Despite being simple in composition, the king cobra venom is potent. Photo by Gerry Martin.

Despite similarities in their appearance and names, the spectacled cobra (Naja naja) and the king cobra (Ophiophagus hannah) are different species with different venom ecology. The researchers compared the venom ecology, biochemistry, pharmacological activity and potency of the king cobra from the Western Ghats of South India with the more familiar spectacled cobra venom.

The king cobra venom is commonly believed to be not as potent as the spectacled cobra venom, a reason often cited for its high yield — as much as 900 mg in a single bite. The study, however, revealed that the king cobra venom is superficially simple due to lesser diversity of toxin types but it is as potent as the spectacled cobra venom, scientist Kartik Sunagar of Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, who led the study, told Mongabay India.

“Another important finding of the study is that the existing antivenoms do not neutralise king cobra venom,” he said. People at risk of king cobra bites stock the Thai Red Cross monovalent antivenom (made in Thailand against king cobra venoms in Thailand and Malaysia) but that doesn’t have an effect on the Indian king cobra bites. Earlier, biogeographical studies have proven that snake venom compositions vary dramatically across geographies. The Indian polyvalent antivenom too is ineffective since king cobra venom is not a part of the immunisation mixture.

Herpatologists Gerry Martin and Romulus Whitaker extract venom from a king cobra for the study.
Snake researchers Gerry Martin and Romulus Whitaker extract venom from a king cobra for the study. Venoms of O. hannah and N. naja were collected from adult males, one individual of each species from Agumbe and Mysuru in Karnataka. Photo by Hemanth Byatroy.

The longest venomous snake in the world, the king cobra is shy and avoids confrontation with humans. Accidental bites and envenoming are uncommon due to its large size and unmissable threat display (hooding and hissing). A Schedule II species, it enjoys high protection under the Wildlife Protection Act 1972, making venom collection for research a tedious process, say researchers. These are some reasons why king cobra venom studies are almost absent in India.

What you eat is what you are

The comparative analysis of the venom compositions for the king cobra and spectacled cobra, revealed a higher venom complexity in the spectacled cobra with a greater number of toxin superfamilies compared to the king cobra venom. Scientists attributed the variation in venom diversity to their distinct dietary preferences with the king cobra being a specialist predator, feeding mostly on snakes. Sunagar said that this could mean it needs only a limited variety of toxins whereas the spectacled cobra, that feeds on a diverse range of prey, might need a wider repertoire of toxins. The same could be the reason for the high venom yield of the king cobra since it sometimes needs to overpower large, venomous snakes like other king cobras it preys on. It could also be due to the large venom glands it possesses.

Sunagar said that these findings are applicable only in the Western Ghats considering the biogeographical variations of snake venoms. He proposes producing a small batch of king cobra monovalent antivenom as a lifesaving drug for king cobra bites in the region as an outcome of the findings. Similar studies should be done in other regions where king cobras are found, he said.

Read more: New study sheds light on lack of research in snake antivenoms


Banner image: No antivenom in the market can neutralise king cobra venom which is found to be as potent as the spectacled cobra venom. Photo by Kalyan Varma.

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