Diversity and Distribution of Medically Important Snakes of India

Abstract

Of the 285 species of snakes found in India, only four are thought to be responsible for the majority of life-threatening bites, spectacled cobra (Naja naja), Russell’s viper (Daboia russelii), common krait (Bungarus caeruleus), and saw-scaled viper (Echis carinatus), the so-called Big Four . The only available antivenom in India targets the bites of these four species. While it is true that these four species are the most medically important Indian snakes, the challenge of saving lives from snakebite is much more complex.

India has four species of cobras, eight species of kraits, and two subspecies of saw-scaled vipers, all of which must be considered medically important. Additionally, several other species like king cobra, some sea snakes, and at least two pit viper species can be classed as medically important based on clinical records of (sometimes single) fatalities from their bites. Further studies are required to determine if there are other species of Indian snakes that can be so classified. It is not known whether the existing Big Four antivenom is effective against the venom of these other or related species, a neglected research area that urgently needs addressing. The venom of Russell’s viper is reported to vary significantly in its clinical effects in different parts of its range which has implications for the production of regionally specific antivenom (Jayanthi and Gowda 1988).

To compound the problem, the distribution of most of these less well-known species is still poorly known. Further, in a country as vast as India, there are different assemblages of venomous snakes in different parts of the country. For example, there are no true vipers in the northeast, and in Eastern India, the spectacled cobra is largely replaced by the monocled cobra. Local anecdotal accounts (particularly in the northeast where large pit vipers occur) suggest several pit viper species that may cause significant morbidity and occasional mortality. The kraits are all known to possess very toxic venoms, but so far, antivenom is only made for the widely distributed common krait, Bungarus caeruleus.