Emergency Flowchart

Signs and symptoms¹	Supportive emergency medical treatment	Identification of the culprit	Antivenom

	Possible culprit²


Nausea, vomiting, abdominal pain, diarrhoea, urticaria, angio-oedema, bronchospasm, arterial hypotension (autopharmacological effects of the venom including anaphylaxis) Autopharmacological syndrome³	Treatment of anaphylactic/anaphylactoid reactions	Identification strategies 1. Morphological identification key (if snake is available for identification) 2. Narrowing down the cause with the aid of indirect criteria (if the snake is unavailable or could not be unequivocally identified) Which snake species are present in the country where the snake bite took place? Under what circumstances did the snake bite occur, and how did the snake behave? Syndromic approach: How does the clinical picture of snakebite envenoming develop? Comparative observations of the various species responsible in the region. Follow also links to species- and family-specific 'clinical entries' in the column `possible culprit' of this flowchart.	WHO Snakebite Information and Data Platform Check for nationally / regionally available antivenoms (assure safety and effectiveness) Antivenom indications and antivenom therapy: go to 'clinical management' Check for updates in case of an accident

	Daboia sp.

Generalised oedema → hypovolaemia → hypovolaemic shock. Capillary leak syndrome (CLS)⁴	Treatment of hypovolaemia/ hypovolaemic shock

	Daboia sp.

Extensive local swelling possibly involving the trunk → hypovolaemia → hypovolaemic shock (local effect of the venom: regionally increased capillary permeability).	Treatment of hypovolaemia/ hypovolaemic shock

	Calloselasma rhodostoma Hypnale sp. Trimeresurus sp.⁵

Systemic bleeding (haemostatic effects of the venom) → haemorrhagic shock. Intracranial bleeding (haemostatic effects of the venom) → focal neurological deficits, coma, meningismus.	Treatment of blood loss Treatment of intracarnial bleeding

	Calloselasma rhodostoma Daboia sp. Echis sp. Hypnale sp. (Trimeresurus sp.⁵)

Bleeding into pituitary and / or adrenal glands (haemostatic effects of the venom).	Treatment of pituitary and / or adrenal insufficiency

	Daboia sp.⁶

Severe anaemia (haemolysis - TMA) - delayed	Treatment of severe anaemia (blood transfusion)

	Daboia sp.⁷ Echis sp.⁷ Hypnale sp.⁷

Cranial nerve deficits, paralysis of the skeletal musculature including the respiratory musculature (neurological effects of the venom) → respiratory insufficiency, respiratory failure	Treatment of respiratory insufficiency/ respiratory failure: In Naja sp. envenoming trial of acetylcholinesterase inhibitors

	Bungarus sp.⁸ Naja sp.^9,10Ophiophagus sp.¹⁰ (Daboia sp.)¹¹

Myalgia, pain on active/passive movement, upon pressure (muscular effect of the venom: rhabdomyolysis) → ECG changes (hyperkalaemia), signs of paralysis, urine colour (differential diagnosis haemoglobinuria), renal failure	Treatment of hyperkalaemia, prevention and treatment of acute renal failure, treatment of respiratory insufficiency/ respiratory failure

	Bungarus niger (and possibly other kraits) (Daboia sp.)¹²

Myocardial symptoms, cardiac dysrhythmias, ischaemia (ECG), cardiac insufficiency, heart failure (usually secondary, rarely primary cardiac effects of the venom)	Treatment of the cardiac disturbance

	(Naja sp.) (Calloselasma rhodostoma)

Acute renal failure (usually secondary and primary renal effects of the venom)	Treatment of acute renal failure

	Daboia sp.¹³Hypnale sp.¹³

Eyes: Intense local pain; blepharospasm; palpebral oedema; leucorrhoea; photophobia, clouding of vision, temporary blindness	see Clinical management; Local treatment

	Asian spitting cobras¹⁴

This section contains genera and species for which clinical data is either sparse or entirely missing. In this case, the link will lead you to the biological file. Under 'Risk', you will find what is known about the potential harm to humans which are well described for adjacent regions but not for the region you are currently looking at. The link will take you to the biological file and from there to the clinical file. When using the clinical information, however, you must consider that it is not from your region and therefore may not be applicable to your situation.	Follow ABCDE approch

	Colubridae Calliophis sp. Hemibungarus sp. Sinomicrurus sp. Azemiops sp. Eristicophis macmahoni Pseudocerastes persicus Macrovipera lebetinus Gloydius sp. Deinagkistrodon acutus

1	See also Clinical flowchart as a guide to the dynamics of envenoming.
2	Taxonomic name without parentheses/(in parentheses)/((in double parentheses)): these signs and symptoms are regularly/(rarely)/((questionably)) observed following bites by these species.
3	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)
4	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. These features were first reported in Burma from envenoming by D. siamensis and in India from D. russelii (Warrell and Williams 2023).
5	Also: Craspedocephalus sp., Protobothrops sp. and Tropidolaemus sp.
6	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.
7	Thrombotic microangiopathy (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).
8	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.
9	Neurological effects with signs of paralysis, including the respiratory musculature, of varying severity. Very significant and well documented with Naja naja and Naja philippinensis. With other Naja species the local effects often dominate (e.g. Naja kaouthia).
10	“Intractable hypotension can occur in patients envenomed by Asian cobras and king cobras, despite adequate respiratory support.” (Warrell 2023)
11	Daboia russelii (Sri Lanka, South India): Mostly mild neuromuscular dysfunction with no long-term effects.
12	Daboia russelii: Mild and non-life threatening, as evident from the low frequency of generalized myotoxicity and low concentrations of serum creatine kinase in envenomed patients. There is a small possibility that myotoxicity may occur in patients with severe envenoming in which antivenom is delayed (Silva et al. 2016b).
13	“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)
14	Local symptoms of envenoming in the eyes (Spitting cobras: Naja mandalayensis, Naja philippinensis. Naja samarensis, Naja siamensis, Naja sputatrix, Naja sumatrana and to some extend also Naja kaouthia). Venom ophthalmia from Asian species are considered less severe than that from African species. Intense local pain; Blepharospasm; Palpebral oedema; Leucorrhoea; photophobia, clouding of vision, temporary blindness (Chu et al. 2010, Warrell 2023, WHO 2016).