Snake bite in South Asia: a review

Abstract

Snake bite is one of the most neglected public health issues in poor rural communities living in the tropics. Because of serious misreporting, the true worldwide burden of snake bite is not known. South Asia is the world's most heavily affected region, due to its high population density, widespread agricultural activities, numerous venomous snake species and lack of functional snake bite control programs. Despite increasing knowledge of snake venoms' composition and mode of action, good understanding of clinical features of envenoming and sufficient production of antivenom by Indian manufacturers, snake bite management remains unsatisfactory in this region. Field diagnostic tests for snake species identification do not exist and treatment mainly relies on the administration of antivenoms that do not cover all of the important venomous snakes of the region. Care-givers need better training and supervision, and national guidelines should be fed by evidence-based data generated by well-designed research studies. Poorly informed rural populations often apply inappropriate first-aid measures and vital time is lost before the victim is transported to a treatment centre, where cost of treatment can constitute an additional hurdle. The deficiency of snake bite management in South Asia is multi-causal and requires joint collaborative efforts from researchers, antivenom manufacturers, policy makers, public health authorities and international funders.

Figure 1. Gum bleeding after bite by Russell's viper.

In Asia, coagulation defects and spontaneous bleeding are characteristic of bites by viperid snakes and are caused by procoagulant and haemorrhagic toxins in the snake venom. Image credit: D. A. Warrell.

Figure 2. “Broken neck” sign observed in a 14-year-old girl bitten by a Russell's viper in India.

Envenoming by cobras, kraits and—in some areas—by Russell's viper frequently leads to progressive descending paralysis. Looking for the broken neck sign, which is caused by paralysis of the neck flexor muscles, should be part of the routine clinical assessment of patients. In this case, neuroparalysis persisted for five days despite antivenom treatment, but without progression toward respiratory failure. Image credit: H. S. Bawaskar.

Figure 3. Tourniquet on a 43-year-old woman presenting at a rural health post in Nepal.

First-aid methods applied throughout South Asia are largely inadequate. Tourniquets in particular can have deleterious effects. This patient consulted after being bitten by a nonvenomous rat snake (Ptyas mucosa) that she had killed and brought for identification. After reassurance, local treatment, and observation, she was uneventfully discharged from the health post. Image credit: E. Alirol.