Examine the bite site for any evidence of fang marks or local envenomation.
Fang marks or patterns play no part in determining whether the biting species was venomous or non-venomous, the amount of venom injected, the degree of systemic poisoning, or the kind of the poisoning – Elapidae or viperidae venom, for example.
Some species, such as Krait, may not leave any bite scars.
Asymptomatic (i.e., non Venom related symptoms)
Patients many a times present with nonspecific symptoms related to anxiety. Common symptoms in these patients are:
– Palpitations, sweating, tremoulessness, tachycardia, tachypnoea, elevated blood pressure, cold extremities and paraesthesia. These patients may have dilated pupils suggestive of sympathetic over activity.
– Differentiate from symptoms and signs of envenomation listed below.
– Redness, increased temperature, persistent bleeding and tenderness locally.
However, local swelling can be present in these patients due to tight ligature
– Bites by nonvenomous snakes are common and bites by venomous species are not always accompanied by the injection of venom (dry bites).
– The percentage of dry bites ranges from 10–80% for various poisonous snakes.
– Some people who are bitten by snakes (or suspect or imagine that they have been bitten) or have doubts regarding bite may develop quite striking symptoms and signs, even when no venom has been injected due to understandable fear of the consequences of a real venomous bite.
– Even in case of dry bite, symptoms due to anxiety and sympathetic overactivity (as above) may be present. As symptoms associated with panic or stress sometimes mimic early envenoming symptoms, clinicians may have
difficulties in determining whether envenoming occurred or not.
Neuroparalytic (Progressive weakness; Elapid envenomation)
–Patients with neuroparalytic snakebite appear with usual symptoms between 30 minutes–6 hours in the event of Cobra bite and 6–24 hours in the case of Krait bite; nevertheless, ptosis in Krait bite has been observed as late as 36 hours following hospitalization.
– These symptoms can be remembered as 5 Ds and 2 Ps.
• 5 Ds – dyspnea, dysphonia, dysarthria, diplopia, dysphagia
• 2 Ps – ptosis, paralysis
– In chronological order of appearance of symptoms – furrowing of forehead,
Ptosis (drooping of eyelids) occurs first (Figure 3), followed by Diplopia
(double vision), then Dysarthria (speech difficulty), then Dysphonia (pitch of
voice becomes less) followed by Dyspnoea (breathlessness) and Dysphagia
(Inability to swallow) occurs. All these symptoms are related to 3rd, 4th, 6th
and lower cranial nerve paralysis. Finally, paralysis of intercostal and skeletal
muscles occurs in descending manner.
– Other signs of impending respiratory failure are diminished or absent deep tendon reflexes and head lag.
– Additional features like stridor, ataxia may also be seen.
– Associated hypertension and tachycardia may be present due to hypoxia.
– To identify impending respiratory failure bedside lung function test in adults viz.
• Single breath count – number of digits counted in one exhalation – >30 normal
• Breath holding time – breath held in inspiration – normal > 45 sec
• Ability to complete one sentence in one breath.
– Cry in a child whether loud or husky can help in identifying impending respiratory failure.
– Bilateral dilated, poorly or a non-reacting pupil is not the sign of brain dead in elapid envenoming.
– Refer patients presenting with neuroparalytic symptoms immediately to a higher facility for intensive monitoring after giving Atropine Neostigmine (AN) injection (schedule of AN injection described below).
Vasculotoxic (haemotoxic or Bleeding) – General signs and symptoms of Viperine envenomation)
Vasculotoxic bites are due to Viper species. They can have local manifestations as well as systemic manifestations.
– Local manifestations, these are more prominent in Russel’s viper bite followed by Saw scaled viper and least in Pit viper bite. Local manifestations are in form of:
• Local swelling, bleeding, blistering, and necrosis.
• Pain at bite site and severe swelling leading to compartment syndrome.
Pain on passive movement. Absence of peripheral pulses and hypoesthesia over the fuels of nerve passing through the compartment, helps to diagnose compartment syndrome.
• Tender enlargement of local draining lymph node.
– Systemic manifestations –
• Visible systemic bleeding from the action of haemorrhagins e.g. gingival bleeding, epistaxis, ecchymotic patches, vomiting, hematemesis, hemoptysis, bleeding per rectum, subconjunctival hemorrhages, continuous bleeding from the bite site, bleeding from pre-existing conditions e.g. haemorrhoids, bleeding from freshly healed wounds.
• Bleeding or ecchymosis at the injection site is a common finding in Viper bites.
• The skin and mucous membranes may show evidence of petechiae, purpura ecchymoses, blebs and gangrene.
• Swelling and local pain.
• Acute abdominal tenderness may suggest gastro-intestinal or retro peritoneal bleeding.
• Lateralizing neurological symptoms such as asymmetrical pupils may be indicative of intra-cranial bleeding.
• Consumption coagulopathy detectable by 20WBCT, develops as early as within 30 minutes from time of bite but may be delayed.