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  1. Terrestrial snakes
  2. Indian Subcontinent and Southeast Asia
  3. Clinical Flowchart

Clinical Flowchart

Autopharmacological effects

Daboia sp.
             
Minutes1 Hours to days2
   
Nausea, vomiting, abdominal pain, diarrhoea
(urticaria, angio-oedema)
(bronchospasm)
arterial hypotension		 Daboia siamensis (Myanmar), Daboia russelii (India)
       

Non-cardiogenic pulmonary oedema

Cerebral oedema

 Generalised oedema
 
Hypovolaemia/hypovolaemic shock
     

Cardiovascular failure
CNS failure
1 Autopharmacological syndrome
“Acute profound hypotension with or without other features of anaphylaxis is part of the autopharmacological syndrome which may occur within minutes of bites by Daboia species. It may be caused by release of endogenous vasoactive compounds such as nitric oxide, kinins, histamine, serotonin and endothelins.” (Warrell 2023)
2 Capillary leak syndrome (CSL)
CLS is unique for Russell's viper envenoming and includes chemosis, periorbital, and facial oedema, bilateral parotid swelling, pleural effusions, ascites, macular oedema, acute angle-closure glaucoma, haemoconcentration, proteinuria, and hypovolaemic shock with low central venous pressure. Patients with CLS are unresponsive to antivenom and are at increased risk of acute kidney injury and death. Symptoms usually appear 12–48 h after the bite (Warrell and Williams 2023). 

Local effects

Naja sp.1
Ophiophagus sp.
Echis sp.
Daboia sp.2
Calloselasma rhodostoma
Hypnale sp.
Trimeresurus sp. 
Craspedocephalus sp.
Protobothrops sp.
Tropidolaemus sp.
Minutes (to hours)
         
Local pain and swelling
         
Painful swelling of the regional lymph nodes
                          
Naja sp.1
Ophiophagus sp.
Calloselasma rhodostoma 
Hypnale sp.
(Trimeresurus sp.) 		Calloselasma rhodostoma
Hypnale sp.
Trimeresurus sp. 
Craspedocephalus sp.
Protobothrops sp.
Tropidolaemus sp. 
Days Hours
   
 Extensive swelling
 
Hypovolaemia
 
Necrosis
Loss of function of extremities
Loss of extremities		    
1 Naja mandalayensis, Naja philippinensis. Naja samarensis, Naja siamensis, Naja sputatrix, Naja sumatrana and to some extent also Naja kouthia can also cause local symptoms of envenoming in the eyes (Spitting cobras).
2

Local signs & symptoms can be mild or absent (Warrell 1989).

Haematological effects

Echis sp.
Daboia sp.1,2 
Calloselasma rhodostoma
Trimeresurus sp.
Craspedocephalus trigonocephalus
Hypnale sp.1
< 1 hours to hours
    
Gingival bleeding
    
Bleeding from wounds remote from the site of the bite
 
Haematemesis, bleeding per rectum, haematuria
     
Systemic bleeding Intracranial bleeding2 
(focal neurological deficits, 
meningismus, coma)
 
Hypovolaemia/haemorrhagic shock
       
Cardiovascular failure Renal failure
CNS failure
1 Additionally, thrombotic microangiopathy (TMA). TMA with acute kidney injury is increasingly recognised in patients envenomed by Russell’s vipers and a variety of other species.” (Warrell and Williams 2023).
2 Addionally, bleeding into pituitary and / or adrenal glands (haemostatic effects of the venom) → Acute, delayed and chronic pituitary or adrenal insufficiency and diabetes insipidus. Hypopituitarism following Daboia siamensis envenoming (Antonypillai et al 2011, Warrell and Williams 2023).
To date, acute pituitary/adrenal insufficiency has been reported in Myanmar, southern India and Sri Lanka. 

Neurological effects

Bungarus sp.1 
Naja sp.2 
Ophiophagus sp.2 
(Daboia russelli)3
Minutes to hours
 
Cranial nerve deficits (ptosis, ophthalmoplegia, dysphagia, dysarthria)
 
Paralysis of the skeletal musculature including the respiratory musculature
 
Respiratory failure
1 Krait bites in particular may be completely unnoticed and unrecognised initially, as these snakes often bite people at night while they are asleep. A krait bite is thus an important differential diagnosis of signs of paralysis (of the cranial nerves, extremities, respiratory musculature).
Abdominal pain is recognized as a characteristic symptom of kraits.
Hyponatraemia → Hypotension / shock; brain damage.
2 “Intractable hypotension can occur in patients envenomed by Asian cobras and king cobras, despite adequate respiratory support.” (Warrell 2023) 
3 Daboia russelii (Sri Lanka, South India): Mostly mild neuromuscular dysfunction with no long-term effects.

Muscular effects

Daboia russelii (Sri Lanka, India)1
Bungarus niger (and possibly other kraits)
Hours
 
Myalgia (at rest, with active/passive movement, upon pressure), dark urine, ECG changes
 
Signs of paralysis
 

 Skeletal muscle necrosis
Renal failure 
1  mostly mild

Cardiac effects

?
?
 
Cardiac dysrhythmias, ischaemia (ECG)
 
Arterial hypotension, pulmonary oedema
 
Heart failure

Renal effects

Daboia sp.1 
Hypnale hypnale1
Hours to days
 
Flank pain, renal bed sensitive to percussion
 
Urinary output <400 ml/24 h
 
Renal failure
1 “Envenoming by many snake species occasionally results in acute kidney injury, but Russell’s vipers are the most dangerous. Acute kidney injury is the major cause of mortality and morbidity among people who have been bitten by these species. Direct venom nephrotoxicity, renal ischaemia secondary to shock, disseminated intravascular coagulation with thrombotic microangiopathy (TMA), haemoglobinuria, myoglobinuria, and hyperkalaemia contribute to acute tubular necrosis.” (Warrell and Williams 2023).