Vulnerability to snakebite envenoming: a global mapping of hotspots

Abstract

SummaryBackgroundSnakebite envenoming is a frequently overlooked cause of mortality and morbidity. Data for snake ecology and existing snakebite interventions are scarce, limiting accurate burden estimation initiatives. Low global awareness stunts new interventions, adequate health resources, and available health care. Therefore, we aimed to synthesise currently available data to identify the most vulnerable populations at risk of snakebite, and where additional data to manage this global problem are needed.MethodsWe assembled a list of snake species using WHO guidelines. Where relevant, we obtained expert opinion range (EOR) maps from WHO or the Clinical Toxinology Resources. We also obtained occurrence data for each snake species from a variety of websites, such as VertNet and iNaturalist, using the spocc R package (version 0.7.0). We removed duplicate occurrence data and categorised snakes into three groups: group A (no available EOR map or species occurrence records), group B (EOR map but <5 species occurrence records), and group C (EOR map and ≥5 species occurrence records). For group C species, we did a multivariate environmental similarity analysis using the 2008 WHO EOR maps and newly available evidence. Using these data and the EOR maps, we produced contemporary range maps for medically important venomous snake species at a 5 × 5 km resolution. We subsequently triangulated these data with three health system metrics (antivenom availability, accessibility to urban centres, and the Healthcare Access and Quality [HAQ] Index) to identify the populations most vulnerable to snakebite morbidity and mortality.FindingsWe provide a map showing the ranges of 278 snake species globally. Although about 6·85 billion people worldwide live within range of areas inhabited by snakes, about 146·70 million live within remote areas lacking quality health-care provisioning. Comparing opposite ends of the HAQ Index, 272·91 million individuals (65·25%) of the population within the lowest decile are at risk of exposure to any snake for which no effective therapy exists compared with 519·46 million individuals (27·79%) within the highest HAQ Index decile, showing a disproportionate coverage in reported antivenom availability. Antivenoms were available for 119 (43%) of 278 snake species evaluated by WHO, while globally 750·19 million (10·95%) of those living within snake ranges live more than 1 h from population centres. In total, we identify about 92·66 million people living within these vulnerable geographies, including many sub-Saharan countries, Indonesia, and other parts of southeast Asia.InterpretationIdentifying exact populations vulnerable to the most severe outcomes of snakebite envenoming at a subnational level is important for prioritising new data collection and collation, reinforcing envenoming treatment, existing health-care systems, and deploying currently available and future interventions. These maps can guide future research efforts on snakebite envenoming from both ecological and public health perspectives and b...

Epidemiology, ecology and human perceptions of snakebites in a savanna community of northern Ghana

“…Snakebite envenomations constitute one of the most important human-wildlife conflicts, causing considerable yet largely insufficiently known magnitudes of socio-economical losses, morbidity and death [1]. Globally, out of >3,500 snake species, ∼600 are venomous, and ∼280 are considered medically important, causing a conservatively estimated >1.2 million snakebite envenomations causing ∼100.000 deaths and >400,000 cases of morbidity annually [1, 2, 3, 4]. Prevailing conservative estimates of the global burden of snakebite envenomations and fatalities are probably highly underrated as majority are based on conventional health facility reports, largely neglecting cases treated by local traditional medical practitioners (TMPs) [1, 5, 6].…”

“…In many parts of sub-Saharan Africa, the high mortality and morbidity rates are attributed to increased vulnerability caused by both high work risk and exposure to diverse snake habitats, as well as poor infrastructure and limited access to appropriate medical treatment and health facilities [1, 4, 6]. Currently, an estimated ∼100 million people, particularly in southeast Asia and Africa, live in vulnerable areas with very high exposure to snake envenomation and lack of effective antivenom therapy [4]. The current ‘global snakebite crisis’ as a disease of poverty, has been termed misunderstood, underrated, ignored or neglected as a public health issue [5, 8, 11, 12], and has lately gained prominence as one of the most important ‘neglected tropical diseases’ [7].…”

A Bayesian phase 2 model based adaptive design to optimise antivenom dosing: application to a dose-finding trial for a novel Russell’s viper antivenom in Myanmar

“…Snake-bite envenoming (SBE) was re-categorized as a priority neglected tropical disease by the World Health Organization (WHO) in 2017 [1, 2]. Worldwide, there are as many as 2.7 million people affected by SBE resulting in an estimated 81,000 to 138,000 deaths per year [3, 4], the burden of which disproportionately affects the poorest communities [5, 6]. Antivenom is considered to be one of the most cost effective health interventions [7].…”

Preclinical validation of a repurposed metal chelator as a community-based therapeutic for hemotoxic snakebite

“…The highest burden of snakebite is suffered by the rural impoverished communities of low/middle income countries, who often rely on agricultural activities for their income (3). These activities put them at risk of snakebite by being exposed to environments inhabited by venomous snakes, and the remoteness of many of these communities makes accessing healthcare problematic (4). Consequently, it is estimated that 75% of snakebite fatalities occur outside of a hospital setting (5), as victims are often delayed in reaching a healthcare facility due to long travel times and/or suboptimal health seeking behaviors.…”