Clinic: Micrurus sp.

Examine for venom effects

Local Effects

Pain
Redness, minor swelling

Neurological effects

Descending flaccid paralysis
- Ptosis (not to be mixed up with tiredness / drowsiness; test: lid retraction with upward gaze).
- Double vision (external ophthalmoplegia)
- Difficulties to swallow (dysphagia) (bulbar paralysis) > inhalation of vomitus!
- Difficulties to lift the head when lying on the back (‘broken neck syndrome’)
- Cyanosis, shallow breathing, respiratory arrest (respiratory paralysis); respiratory arrest may be precipitated by obstruction of the upper airway by the paralysed tongue or inhaled vomitus.
- Weakness or loss of voluntary movement; movements of digits may still be possible, allowing the patient to communicate.
- Loss of consciousness and generalized convulsions caused by hypoxaemia in patients who have respiratory paralysis.

(Muscular effects)

Generalized rhabdomyolysis:
- Muscles pain and tenderness, painful on passive stretching, muscle stiffness, trismus
- Bulbar and respiratory muscle weakness.
- Dark brown urine.
- Renal failure (AKI)
- Laboratory: Generalized rhabdomyolysis: defined by a serum creatine kinase level > 10,000 U/l
- ECG: Signs of hyperkalaemia.

Species-specific envenoming pattern

The assessment of the envenoming pattern is based on the data from publication in which the identification of the snakes is clearly specified and in accordance with accepted criteria.

	Local effects¹	Neurological effects²	Musular effects³
Micrurus fulvius
Micrurus laticollaris
Micrurus lemniscatus
Micrurus mipartitus
Micrurus tener		?

The overall picture of coral snakes (Micrurus spp.) envenoming

¹Local effect

Often complete lack of any local signs at the bite site despite severe envenoming; e.g.in a Micrurus lemniscatus helleri bite. However, with severe pain and paraesthesia in the bitten limb despite morphine and tranquilizers (Manock et al. 2008).

“Micrurus venoms differ in their oedema-forming effects, with the Central American M. nigrocinctus having the greatest effect clinically” (Manock et al. 2008).

Local numbness/paraesthesia, pain, mild swelling (Bucaretchi et al. 2016)

Haematological effects

Haematological effects are very uncommon in Micrurus envenoming. Thrombocytopenia and mild coagulopathy, no bleeding has been reported in a patient envenomed by Micrurus lemniscatus (Manock et al. 2008).

²Neurological effects

Typical neurological effects of envenoming have been observed developing with a lack period of 14 hrs after the bite (Manock et al 2008). The reported onset of respiratory muscle paralysis ranges from a few hours to 60 hrs (need of oxygen) to 72 hours (need of intubation and mechanical ventilation) with recurring respiratory distress for 38 hrs (Micrurus lemniscatus helleri; Manock et al. 2008).

In 20 clearly identified Micrurus fulvius (described as M. fulvius fulvius) bites in 14 of 15 patients, the average time between the bite and appearance of the first symptoms of envenoming was 140 min (30–780 min)In one case the delay between the bite and the onset of severe envenoming (complete paralysis including respiratory muscles) was delayed for 13 hours after the bite with a, then, precipitous onset (Kitchens and Van Mierop 1987).

Neurological effects include autonomous nervous system activity (profuse sweating, urinary incontinence) (Warrell 2004; Manock et al. 2008).

³Muscular effects

In human envenoming muscular effect have been described in bites by Micrurus lemniscatus (modest increase in serum creatine kinase activity, from 256 to 749 U/l) (Manock et al. 2008), by Micrurus fulvius (generalised myalgia with evidence of gross rhabdomyolysis with serum creatine kinase levels of up to 18 000 U/l) (Kitchens and Van Mierop 1987). And, also mild, in a patient bitten by Micrurus laticollaris (CK 1,392 U/l (normal 8–132 U/l); LDH 945 U/l (normal 83–200 U/l)) (Pettigrew and Glass 1985).

Clinical management

Clinical Management: South America and the West Indies

Clinical Management: Mexico and Central America

Clinical Management: North America

for advice on post-First Aid measures, diagnosis (clinical, laboratory) and treatment (supportive, antivenom).

First Aid

Release of any type of tourniquet follow links above.

Local treatment

Pain control
Tetanus prophylaxis
Standard wound care
WHO (2010)

Systemic supportive treatment

A general understanding of emergency medicine is required, or can be found in emergency medicine guidelines, e.g. ABCDE approach, WHO-ICRC Basic Emergency Care.

Follow SAMPLE & ABCDE Approach

Comprehensive ABCDE approach

ICRC Basic Emergency Care: approach to the acutely ill and injured (SAMPLE and ABCDE approach: first module)

Obey Micrurus sp. - specific features

see 'Species-specific envenoming pattern above'.

Key issues

Respiratory failure

Lifesaving in neurotoxic snakebite envenoming (as supportive treatment and when Antivenoms are not available or fail):

Airway management

Breathing: Oxygen⇨assisted ventilation⇨mechanical ventilation

A trial of anticholinesterase drugs to improve neuromuscular transmissionappears is reasonable (Manock et al. 2008).

Specific treatment (antivenoms)

„Early administration of antivenom is recommended to allow neutralisation of neuro toxins before they have become bound, perhaps irreversibly in the case of pre-synaptic toxins, to their receptor targets at neuromuscular junctions. This was the basis of the recommendation in the United States that coral snake antivenom be given immediately in any case of definite coral snake bite, even before any signs of envenoming have appeared.” (Manock et al. 2008).

WHO Snakebite Information and Data Platform

Species-specific evidence

Micrurus fulvius (descriped as M. fulvius fulvius)

United States

Kitchens CS, Van Mierop LH. Envenomation by the Eastern coral snake (Micrurus fulvius fulvius). A study of 39 victims. JAMA. 1987 Sep 25;258(12):1615-8.PMID: 3625968.
Norris RL, Pfalzgraf RR, Laing G. Death following coral snake bite in the United States--first documented case (with ELISA confirmation of envenomation) in over 40 years. Toxicon. 2009 May;53(6):693-7. PMID: 19673084. https://doi.org/10.1016/j.toxicon.2009.01.032
Moseley T. Coral snake bite: recovery following symptoms of respiratory paralysis. Ann Surg. 1966 Jun;163(6):943-8. PMID: 5933807; PMCID: PMC1477049. https://doi.org/10.1097/00000658-196606000-00016
McCullough NC, Gennaro JF. Coral snake bites in the United States.J Fla Med Assoc. 1963;49:968–972.

Micrurus laticollaris

Mexico

Pettigrew LC, Glass JP. Neurologic complications of a coral snake bite. Neurology. 1985 Apr;35(4):589-92. PMID: 3982652. https://doi.org/10.1212/wnl.35.4.589

Micrurus lemniscatus

Ecuador

Manock SR, Suarez G, Graham D, Avila-Aguero ML, Warrell DA. Neurotoxic envenoming by South American coral snake (Micrurus lemniscatus helleri): case report from eastern Ecuador and review. Trans R Soc Trop Med Hyg. 2008 Nov;102(11):1127-32. Epub 2008 May 16. PMID: 18486170. https://doi.org/10.1016/j.trstmh.2008.03.026

Micrurus mipartitus

Colombia

Cañas CA, Castro-Herrera F, Castaño-Valencia S. Envenomation by the red-tailed coral snake (Micrurus mipartitus) in Colombia. J Venom Anim Toxins Incl Trop Dis. 2017 Feb 14;23:9. PMID: 28228775; PMCID: PMC5307858. https://doi.org/10.1186/s40409-017-0100-4

Micrurus tener (described as M. fulvius tenere)