A review of reported bushmaster (Lachesis spp.) bites in the Americas

Envenomations caused by Lachesis species in the Americas are a rare but medically important condition. The genus Lachesis comprises five species distributed throughout Central and South America. Their venoms induce both local and systemic manifestations, although such accidents are rarely reported in the literature. This study aimed to describe the clinical characteristics of Lachesis envenomations in the Americas through a literature review. A comprehensive search of scientific databases from 1950 to 2023 identified 23 articles reporting 44 confirmed cases of Lachesis envenomation. The accidents were caused by L. muta and L. rhombeata in South America, and by L. stenophrys and L. melanocephala in Central and North America (caused by an imported captive specimen from Costa Rica), occurring mainly in rural environments or during snake handling in captivity. Among the reported cases, 93.2% presented local symptoms, 88.6% systemic manifestations, and two were asymptomatic. Vagal syndrome occurred in 75% of cases, and hemorrhagic manifestations in 20.4%. Regarding severity, 18.2% were mild, 29.5% moderate, 47.7% severe, and 4.5% asymptomatic. The mortality rate was 9.1%, even with antivenom administration. The low number of case reports confirms the rarity of Lachesis envenomation in the Americas. The variability of local and systemic manifestations demonstrates clinical similarities with Bothrops envenomation, highlighting the importance of confirming the offending species, as not all cases present the characteristic vagal syndrome.