Bites by coral snakes (Micrurus spp.) in Campinas, State of São Paulo, Southeastern Brazil

Abstract

SUMMARYCoral snakes (Micrurus spp.) are the main representatives of the Elapidae in South America. However, bites by these snakes are uncommon. We retrospectively reviewed the data from 11 individuals bitten by coral snakes over a 20-year period; four were confirmed (snake brought for identification) and seven were highly suspected (neuromuscular manifestations) cases of elapid envenoming. The cases were classified as dry-bite (n = 1, caused by M. lemniscatus; did not receive antivenom), mild (n = 2, local manifestations with no acute myasthenic syndrome; M. frontalis and Micrurus spp.), moderate (n = 5, mild myasthenia) or severe (n = 3, important myasthenia; one of them caused by M. frontalis). The main clinical features upon admission were paresthesia (local, n = 9; generalized, n = 2), local pain (n = 8), palpebral ptosis (n = 8), weakness (n = 4) and inability to stand up (n = 3). No patient developed respiratory failure. Antivenom was used in ten cases, with mild early reactions occurring in three. An anticholinesterase drug was administered in the three severe cases, with a good response in two. No deaths were observed. Despite the high toxicity of coral snake venoms, the prognosis following envenoming is good. In serious bites by M. frontalis or M. lemniscatus, the venom of which acts postsynaptically, anticholinesterases may be useful as an ancillary measure if antivenom is unavailable, if there is a delay in obtaining a sufficient amount, or in those patients given the highest recommended doses of antivenom without improvement of the paralysis or with delayed recovery.

Envenoming by coral snakes (Micrurus) in Argentina, during the period between 1979-2003

“…The venom of the Argentinean Micrurus is as toxic as the venom of Micrurus that causes death in other countries 13,19,26,34,38 . In Brazil, a country with very similar characteristics regarding the fauna and snakebite epidemiology, Micrurus bites are also uncommon 4,14,25,27,31 and usually mild 6,9 representing about 0.4% of total snakebites with 0.36% mortality 25 , which is very consistent with our results.…”

“…Significant clinical symptoms are recorded in approximately 40% of Micrurus bites reflecting venom inoculation 30,32,33 , which seems to be slightly lower than elapid envenomings reported from other continents where the incidence of clinical disorders is estimated at 50-60% in humans 7,9 . However, it is well known that even a venomous snake may inflict a dry bite 6,35 . It is also possible that the rapid management of patients, half of which are treated within one hour after the bite, could explain the absence of death and severe envenoming among patients of Argentina.…”

“…In Central America and Colombia less than 2% of all snakebites have been related to bites by Micrurus spp. 5,8 , while in Brazil coral snakes accounted for 0.65% (486 out of 75,312) of bites by venomous snakes in the period between 2001-2004, with no recorded deaths 6 . In the United States of America, bites by coral snakes (principally by M. fulvius) represent 3.6% of accidents involving indigenous venomous snakes, based on records from the last 20 years (911 coral snake bites from a total of 25,551 bites by venomous snakes in the period between 1983-2003) 1 , which equates to around 45 bites/ year; while another report accounts for 1254 bites by Micrurus in the period between 1983-2007 41 , leading to 50 ± 31 bites per year, this is in the same range as previous report.…”

“…Micrurus bites produce a neurotoxic envenoming, which can lead to peripheral paralysis of respiratory muscles in animals and humans 6,21,34 . The neurological symptoms may involve 1) a block of the postsynaptic cholinergic receptor by toxic peptides called a-neurotoxins, e.g.…”

Envenomation by Micrurus coral snakes in the Brazilian Amazon region: report of two cases

“…Coral snakes are the main representatives of the Elapidae in the Americas, the genus Micrurus being the most important in terms of public health 4,6 . Due to their large geographical distribution, coral snakes may be found in diverse environments 6,13 .…”