A brief review on the natural history, venomics and the medical importance of bushmaster (Lachesis) pit viper snakes

Abstract

Snakes of the genus Lachesis , commonly known as bushmasters, are the largest venomous snakes in the Americas. Because these snakes have their habitats in areas of remote forests they are difficult to find, and consequently there are few studies of Lachesis taxa in their natural ecosystems. Bushmasters are distributed in tropical forest areas of South and Central America. In Brazil they can be found in the Amazon Rainforest and the Atlantic Forest. Despite the low incidence of cases, laquetic envenoming causes severe permanent sequelae due to the high amount of inoculated venom. These accidents are characterized by local pain, hemorrhage and myonecrosis that can be confused with bothropic envenomings. However, victims of Lachesis bites develop symptoms characteristic of Lachesis envenoming, known as vagal syndrome. An important message of this bibliographic synthesis exercise is that, despite having the proteomic profiles of all the taxa of the genus available, very few structure-function correlation studies have been carried out. Therefore the motivation for this review was to fill a gap in the literature on the genus Lachesis , about which there is no recent review. Here we discuss data scattered in a number of original articles published in specialized journals, spanning the evolutionary history and extant phylogeographic distribution of the bushmasters, their venom composition and diet, as well as the pathophysiology of their bites to humans and the biological activities and possible biotechnological applicability of their venom toxins.

Action of Varespladib (LY-315920), a Phospholipase A2 Inhibitor, on the Enzymatic, Coagulant and Haemorrhagic Activities of Lachesis muta rhombeata (South-American Bushmaster) Venom

“…In Brazil, these snakes are represented by three main genera, i.e., Bothrops , Crotalus and Lachesis (Viperidae–Crotalinae), being responsible for more than 20,000 cases of snakebites per year in this country, as reported by Notifiable Diseases Information System of the Brazilian Ministry of Health (SINAN, Brasília, DF, Brazil). Lachesis snakes found in South America ( L. muta muta and L. m. rhombeata ) occasionally cause severe human envenomations ( Magalhães et al, 2019 ; Diniz-Sousa et al, 2020 ), which are characterized by pronounced local and systemic disorders, e.g., necrosis ( Damico et al, 2006 ; Ferreira et al, 2009 ; Damico et al, 2012 ), haemorrhage, coagulopathy ( Sánchez et al, 1987 ; Sánchez et al, 1991 ; Sánchez et al, 1995 ; Fuly et al, 1997 ; Rucavado et al, 1999 ; Estêvão-Costa et al, 2000 ; Torres-Huaco et al, 2013 ) and hypotension ( Dias et al, 2016a ; Dias et al, 2016b ), strongly associated with a variety of enzymatically active proteins such as snake venom metalloproteases, serine proteases, PLA 2 , C-type lectins and l -amino acid oxidases ( Weinberg et al, 2004 ; Junqueira-de-Azevedo et al, 2006 ; Bregge-Silva et al, 2012 ; Madrigal et al, 2012 ; Cordeiro et al, 2018 ; Diniz-Sousa et al, 2018 ; Wiezel et al, 2019 ) present in these venoms.…”

“…Snakes of Lachesis genus are represented by three species found in Central America ( L. stenophrys , L. melanocephala , and L. acrochorda ) and one in South America ( L. muta ), with the latter being recognized as two subspecies distributed in the Amazon river basin (= L. muta muta ) and Atlantic rainforest (= L. muta rhombeata ) in Brazil ( Costa and Bérnils, 2018 ; Nogueira et al, 2019 ; Diniz-Sousa et al, 2020 ). Together, these snakes are responsible by the second most frequent cases of snakebites in Americas, being exceeded only by Bothrops snakes ( Magalhães et al, 2019 ; Diniz-Sousa et al, 2020 ).…”

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“…), are common prey items in Central America, where, along with suitable habitat, the abundance of snakes is largely dependent on the availability of this food source (Greene and Santana 1983). To our knowledge, no records exist of any bushmasters preying on amphibians, birds, or other reptiles, but we cannot rule out the possibility that at least young individuals might exploit the amphibians (contrary to Diniz-Sousa et al 2020, citing Carrillo de Espinoza 1970 that can be phenomenally abundant in habitats where bushmasters occur. Note, however, that even hatchling bushmasters are large enough to swallow small rodents.…”

Rodent Lethality Models Are Problematic for Evaluating Antivenoms for Human Envenoming

“…and south American Bushmasters (Lachecis sp.) (Gutiérrez et al, 1988;Bard et al, 1994;Diniz-Sousa et al, 2020). Although α-neurotoxins are mostly found in elapids and colubrids, they are present even in some viperid venoms that do not cause neurotoxicity in humans, such as Puff adders (Wang et al, 2020;Youngman et al, 2021) hence the utility of these assays remains narrow.…”