What is the number of krait species found in India?

Kraits in India: Species, Distribution, and Clinical Significance

There are 8-9 species of kraits (genus Bungarus) found in the Indian subcontinent, with Bungarus caeruleus (Common or Indian krait) and Bungarus niger being the most highly venomous species. 1

Species Distribution and Significance

• The Indian subcontinent (including India, Bangladesh, Bhutan, Nepal, Pakistan, Sri Lanka, and Maldives) is home to 8-9 species of kraits 1
• Kraits belong to the genus Bungarus and are part of the Elapidae family of venomous snakes 1
• The Common krait (Bungarus caeruleus) and B. niger are considered the most highly venomous species among the kraits found in India 1
• The Common krait is one of the "Big Four" venomous snakes responsible for the majority of snakebite deaths in India 2

Venom Characteristics and Clinical Significance

• Common krait venom is predominantly composed of phospholipases A2 (64.5% of total proteins), with at least 4.6% being presynaptically-acting β-bungarotoxin A-chains 3
• Three-finger toxins (19.0%) are the second most abundant components, including 15.6% κ-neurotoxins which are potent postsynaptically-acting long neurotoxins 3
• Krait venom causes severe neurotoxicity that can lead to paralysis, respiratory failure, and death within a short time frame 3
• The absence of cytotoxins in krait venom correlates with the lack of local envenoming signs (pain, swelling), making bites potentially insidious until paralysis sets in 3

Clinical Presentation of Krait Bites

• Krait bites typically occur at night while victims are asleep on the floor 4
• Cardinal symptoms include abdominal pain developing within hours of the bite 4
• Altered consciousness is observed in 71% of patients (drowsiness, semiconsciousness, or deep coma) 4
• Autonomic disturbances including transient hypertension, tachycardia, lacrimation, sweating, and salivation occur in 66% of patients with moderate to severe envenomation 4
• Metabolic complications include hypokalaemia (71%) and metabolic acidosis (50%) 4
• Neurological complications include anterograde memory loss (40%) and delayed neuropathy (22%) 4

Treatment and Management

• Anti-snake venom (ASV) is the most specific therapy available for krait envenomation 5
• The polyvalent antivenom produced in India is effective against envenomation by kraits and is used across the Indian subcontinent 5
• High doses of ASV may be required for reversal of neurological manifestations in severe krait envenomation 5
• Early access to mechanical ventilation is critical for reducing mortality in severe cases 4
• Venom samples from Sri Lanka, India, and Pakistan show comparable profiles but variable immunoreactivities to available antivenoms 3

Prevention Strategies

• Regular tick checks on humans and pets after spending time in tick-infested habitats can help prevent tick-borne diseases, which is a general principle that can be applied to snake habitats as well 6
• Use of protective clothing when outdoors, including long-sleeved shirts, pants, socks, and closed-toe shoes can reduce exposure risk 6
• Limiting exposure to snake-infested habitats, especially during nighttime when kraits are most active, is an important preventive measure 6, 4

Understanding the distribution, venom characteristics, and clinical presentation of krait bites is essential for proper management and prevention of envenomation in the Indian subcontinent.