Venom Types of Russell's Viper and Common Krait
Russell's viper produces hemotoxic/cytotoxic venom that causes severe coagulopathy and tissue damage, while the common krait produces neurotoxic venom that primarily causes neuroparalysis and respiratory depression. 1, 2
Russell's Viper Venom Characteristics
Russell's viper (Daboia russelii) venom is predominantly hemotoxic and procoagulant, causing:
- Severe coagulopathy with active bleeding from fang marks and systemic hemorrhage, detectable by positive 20-minute whole blood clotting test (20WBCT) 3, 2
- Rapid local tissue damage with severe edema at the bite site, ecchymosis, and local swelling 2
- Bleeding complications including gastrointestinal hemorrhage and thrombocytopenia 4
- Acute renal failure in severe cases 4
The venom contains metalloproteinases that directly activate Factor X in the coagulation cascade, which is why Russell's viper venom (RVV) is used diagnostically in laboratory assays for measuring coagulation abnormalities 5
Common Krait Venom Characteristics
Common krait (Bungarus caeruleus) venom is predominantly neurotoxic, causing:
- Neuroparalysis with minimal or absent local signs at the bite site 2, 6
- Abdominal pain that precedes neurological symptoms, particularly in victims bitten while sleeping on the floor 2
- Respiratory depression requiring ventilatory support, as the neurotoxins cause respiratory muscle paralysis 7, 2, 6
- Rapid development of neuromuscular blockade that can progress to complete respiratory failure 8, 7
Clinical Implications for Treatment
The venom type fundamentally determines treatment approach:
- For Russell's viper bites: Pressure immobilization may be less beneficial or potentially harmful as it concentrates cytotoxic venom in one area 7
- For common krait bites: Pressure immobilization (40-70 mmHg) is particularly beneficial to slow neurotoxin dissemination through lymphatic channels, and the recommended initial antivenom dose is 10 vials 8, 7
- Antivenom requirements differ significantly: Russell's viper envenomation typically requires higher total doses of antivenom compared to krait bites, despite similar clinical severity 2
Common Diagnostic Pitfalls
- Russell's viper bites present with obvious local signs (severe swelling, bleeding, ecchymosis) making identification easier, while krait bites often have minimal local manifestations that can lead to delayed recognition 2
- The 20WBCT is positive early in Russell's viper envenomation but may be delayed in saw-scaled viper bites, which can cause diagnostic confusion 2
- Neurotoxic effects from krait venom can be mistaken for other causes of altered consciousness if the bite history is unclear, particularly in patients bitten while sleeping 2, 6