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Summary Background Snakebite 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. Methods We 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. Findings We 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. Interpretation Identifying 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 better target future estimates of the burden of this neglected tropical disease.
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www.thelancet.com Published online July 12, 2018 http://dx.doi.org/10.1016/S0140-6736(18)31224-8
1
Articles
Vulnerability to snakebite envenoming: a global mapping of
hotspots
Joshua Longbottom, Freya M Shearer, Maria Devine, Gabriel Alcoba, Francois Chappuis, Daniel J Weiss, Sarah E Ray, Nicolas Ray, David A Warrell,
Rafael Ruiz de Castañeda, David J Williams, Simon I Hay, David M Pigott
Summary
Background Snakebite 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.
Methods We 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.
Findings We 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 eective 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.
Interpretation Identifying 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 eorts on snakebite envenoming from both ecological and public health perspectives and better target future
estimates of the burden of this neglected tropical disease.
Funding Bill & Melinda Gates Foundation.
Copyright © 2018 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.
Published Online
July 12, 2018
http://dx.doi.org/10.1016/
S0140-6736(18)31224-8
See Online/Comment
http://dx.doi.org/10.1016/
S0140-6736(18)31328-X
Big Data Institute, Li Ka Shing
Centre for Health Information
and Discovery
(J Longbottom MSc,
F M Shearer BSc, M Devine MSc,
D J Weiss PhD), and Nuffield
Department of Clinical
Medicine (D A Warrell FMedSci),
University of Oxford, Oxford,
UK; Centre for Health
Informatics, Computing and
Statistics, Lancaster Medical
School, Lancaster University,
Lancaster, UK (J Longbottom);
Department of Vector Biology,
Liverpool School of Tropical
Medicine, Liverpool, UK
(J Longbottom); Division of
Tropical and Humanitarian
Medicine, University Hospitals
of Geneva, Geneva,
Switzerland (G Alcoba MD,
F Chappuis MD); Division of
Tropical Medicine and
Neglected Tropical Diseases,
Médecins Sans Frontières,
Geneva, Switzerland
(G Alcoba); Institute for Health
Metrics and Evaluation,
University of Washington,
Seattle, WA, USA (S E Ray BS,
Prof S I Hay FMedSci,
D M Pigott DPhil); EnviroSPACE
Lab, Institute for
Environmental Sciences
(N Ray PhD), and Institute of
Global Health, Faculty of
Medicine
(R Ruiz de Castañeda PhD,
N Ray), University of Geneva,
Geneva, Switzerland; and
Australian Venom Research
Unit, Department of
Pharmacology and
Therapeutics, University of
Melbourne, Melbourne, VIC,
Australia (D J Williams PhD)
Introduction
Snakebite envenoming is a frequently overlooked
cause of mortality and morbidity, responsible for
81 000–138 000 deaths annually,1,2 and between 421 000 and
1·2 million envenomings.3 Contact from venomous
snakes, spiders, and scorpions contribute to 1·2 million
years of life lived with disability annually.4 The burden
remains poorly characterised because of under-reporting;
as snakebite is rarely notifiable, existing estimates are
typically derived from extrapolated hospital records
and community surveys.5 Snakebite primarily aects the
poor rural communities of Asia and sub-Saharan Africa,
where socioeconomic status and agricultural and other
practices contribute to increased snake–human inter-
action.6 Venomous snakebites can also inflict a heavy
burden on livestock, creating economic hardship for
already impoverished communities.7 Medically important
snake species, however, have a cosmopolitan distribution,
making snakebite a global challenge.3
In June, 2017, snakebite envenoming was classified as a
category A neglected tropical disease,8,9 and was
the subject of a resolution passed by the World Health
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Correspondence to:
Prof Simon I Hay, Institute for
Health Metrics and Evaluation,
University of Washington,
Seattle, WA 98121, USA
sihay@uw.edu
or
Mr Joshua Longbottom,
Department of Vector Biology,
Liverpool School of Tropical
Medicine, Liverpool L3 5QA, UK
joshua.longbottom@lstmed.
ac.uk
Assembly in May, 2018. Consequently, there is a renewed
impetus to accurately assess the burden and distribution
of snakebite to ensure appropriate prevention and control
interventions are implemented, and that adequate
resources and funding are allocated nationally and
subnationally.10,11 For other neglected tropical diseases,
substantive global targets exist: Sustainable Development
Goal target 3·3 aims to “end the epidemics” of these
diseases by 2030,12,13 with routine reporting, surveillance,
and notification architecture in place. As a new neglected
tropical disease, snakebite monitoring and evaluation
should reflect these objectives.
Data for the presence of venomous snakes and
occurrence of snakebites are sparse and incomplete
at the global level, making estimation challenging.14,15
Although some countries have done household-level
surveys to determine the incidence of snakebites,14,15
the global magnitude of this disease remains poorly
characterised. Snakebite envenoming represents an
interesting One Health challenge requiring clinical,
ecological, and public health expertise. Consequently, this
issue can be approached by considering vulnerability to
snakebite envenoming as a nexus of ecological contexts
and public health weaknesses, to provide an evidence
base for targeting future quantitative studies.
Clinical challenges involve appropriate case diagnosis
and adequate provisioning of care whether supportive
(such as ventilators) or direct treatment with antivenom,
which might not be available at any given point of
care.2,16 Ascertainment of the correct antivenom can be
challenging,17 and current diagnostics can be expensive
and slow.18,19 Furthermore, nearly half of venomous snakes
do not have antivenoms available as tracked by WHO.2,20
To comprehensively address snakebites, these clinical
challenges need to be considered within an ecological
context by understanding snake behaviour and life-history
traits that contribute to the frequency and geographical
distribution of snakebites. Therefore, by contextualising
contemporary knowledge about snake distributions with
indicators of the quality of health-care provisioning,21
the accessibility of these resources,22 and antivenom
availability,20 we aimed to identify populations vulnerable
to the worst health outcomes of an envenoming event.
Methods
Study overview
We evaluated range maps for 278 snakes to consider
their presence at a 5 × 5 km (grid cell) resolution. To
identify the most vulnerable populations, this ecological
information was paired with three key metrics: the
Research in context
Evidence before this study
Snakebite envenoming is a category A neglected tropical disease
of particular public health importance in tropical areas of Africa,
Asia, Latin America, and Papua New Guinea. It is estimated that
up to 1·2 million people are envenomed annually, resulting in
81 000–138 000 fatalities. Although effective therapies exist to
treat envenoming by some snakes of highest medical
importance, there are many species without such treatments.
The global distribution of venomous snakes and vulnerable
populations remains inadequately characterised; therefore, the
lack of knowledge of subnational disease burden might impede
production of antivenom supplies and distribution efforts
among populations currently at risk. To investigate this further,
we searched for articles on PubMed published before
March 1, 2017, using the search terms “snakebite”, “distribution”,
and “burden”. Contemporary studies have investigated
venomous snake distributions and snakebite risk at national
levels (several countries in Latin America) or subnational levels
(India, Nigeria, and Sri Lanka), but these studies did not
encompass all medically important snake species and are limited
in both geographical extent and spatial resolution. A more
recent analysis mapped the distribution of venomous snakes in
Central America and Latin America but was restricted to widely
studied species with ample occurrence data. Although an
important start, no study has coupled global ecological
information about snake distributions with measures relating to
public health capabilities to hone in on populations most
vulnerable to this cause of mortality and morbidity.
Added value of this study
We identified populations most vulnerable to 278 medically
important snake species by using expert opinion, species’ ranges
refined by publicly available occurrence data and multivariate
analyses, information about effective therapies, and metrics of
health-care quality and accessibility. Although a large proportion
of the world’s population live in areas where such snakes could be
present, proxy metrics such as the Healthcare Access and Quality
Index and urban accessibility paired with broad-scale information
about market antivenom availability provide a subnationally
resolved yet globally comprehensive picture of vulnerability,
highlighting populations that could be most affected.
Implications of all the available evidence
We highlight locations where the combination of the presence
of a variety of venomous snakes, inequalities in health care and
accessibility, and possible absence of effective therapy might
contribute toward increased vulnerability of snakebite
envenoming. Our analyses can be used to inform the
positioning of local-scale household surveys to assess the true
risk of snakebite in areas where such estimates are currently
inadequate. This study highlights the importance of continuing
to iterate, improve, and re-evaluate existing geographical
assessments of snake distributions, and the need to incorporate
spatially heterogeneous risk within future burden estimation
efforts. This work is a first step in trying to identify and assist
the most neglected populations of this newly designated
neglected tropical disease.
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3
market availability of antivenom therapies as reported
by WHO,20 accessibility to urban centres as a proxy for
access to health care,22 and the Healthcare Access and
Quality (HAQ) Index as a proxy for adequacy and
ecacy of medical interventions at health-care centres.21
Figure 1 shows conceptually how populations lacking in
all these measures should be seen as the most vulnerable
populations, and how these measures could vary
geographically.
Global list of snake species
We assembled a list of snake species, using WHO
guidelines for venomous snake species of medical
importance (hereafter referred to as snakes),23 which
define two tiers of medical importance that reflect
both ecological knowledge on propensity to interact
with humans and clinical grading of toxicity. Category
one species are common or widespread snakes that
result in high morbidity, disability, or mortality. Cate-
gory two species are snakes capable of causing mor-
bidity, disability, or death, or for which epidemiological
or clinical data are missing or are less frequently
implicated.
Where relevant, expert opinion range (EOR) maps
were obtained from WHO blood products online
database or the Clinical Toxinology Resources data-
base.20,24 Occurrence data for each species were obtained
from the Global Biodiversity Information Framework,
VertNet (version 2016-09-29), iNaturalist, iDigBio, and
Ecoengine, using the spocc R package (version 0.7.0) on
May 29, 2017.25 Duplicate records based upon shared
collection year and latitude or longitude and those
missing latitude or longitude were removed.
Given the availability of data, we placed 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). Group A species (n=9)
were excluded from this analysis because of the absence
of geographical information, reducing our species
inclusion list to 278 (99 group B species and 179 group C
species; appendix 1).
Multivariate environmental similarity surface
generation and species’ ranges
For group C species with sucient occurrence records,
potential updates to the EOR maps were assessed. EOR
maps were updated with data that has become publicly
accessible since publication of the WHO EOR maps in
2008. Multivariate environmental similarity method was
applied to the occurrence records obtained for group C
species, situated within the EOR, allowing for rapid
classification of occurrence records outside of the EOR
within the environmental range of other records (ie,
interpolation) or beyond these limits (ie, extrapolation).
Multivariate environmental similarity surfaces (MESS)
measure the similarity between new environments
(records outside of the EOR) and those in the training
sample (records within the EOR), by identifying the
maximum and minimum values of environmental data
within the training sample, with respect to a set of
predictor variables (covariates).26 We fitted species-specific
MESS using occurrence records within the EOR, and
eight bioclimatic covariates thought to influence snake
distribution (appendix 2 provides information about the
MESS parameters and covariate specifics).
Figure 1: Conceptual overview of vulnerability to snakebite envenoming
(A) Vulnerability can be considered as the intersection of populations who live
within the range of venomous snakes that have no antivenoms available,
cannot easily access health care, and have poor quality health care in delivery of
antivenoms or ensuring necessary stocks. The intersection of all three defines
the most vulnerable populations. (B) These factors vary in space. By overlaying
these features, the most vulnerable populations can be identified spatially
(represented here by the boxes outlined in black).
No
antivenom
Poor quality
health care
Inaccessible
health care
Suitable habitat for snakes
No antivenom
Poor quality health care
Inaccessible health care
Suitable habitat for snakes
A
B
For the Global Biodiversity
Information Framework see
https://www.gbif.org/
For more on VertNet see
http://vertnet.org/index.html
For more on iNaturalist see
https://www.inaturalist.org
For more on iDigBio see
https://www.idigbio.org/
For more on Ecoengine see
https://ecoengine.berkeley.edu/
See Online for appendix 1
See Online for appendix 2
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Occurrence records outside of the currently accepted
EOR were overlaid on top of each species-specific threshold
MESS. Records located within cells of environ mental
interpolation (termed MESS-positive) were considered
valid records of species occurrence. Proposed ranges
were developed to encompass all valid MESS-positive
records, generated by applying a buer radius of 0·898°
(approx imately 100 km at the equator) to each MESS-
positive record to address potential movement of species,
and possible geopositioning errors.27,28 Buered locations
were masked by the threshold MESS to remove areas
of environmental extrapolation, and merged with the
currently accepted EOR to produce a proposed con-
temporary range.
Global distribution of snakes
To reflect the geographical diversity of the snakes
studied, we aggregated the ranges of dierent species.
Modified (ie, group C species with MESS-positive
records [n=96]) or original EOR surfaces (group B
and group C species with no MESS-positive records
[n=182]) were converted into 5 × 5 km raster (gridded)
files. They were then stacked by summing overlapping
cell values, resulting in three composite output layers:
a count of the number of unique category one or
category two species per cell, or both; a count of the
number of unique category one species per cell; and a
count of the number of unique category two species
per cell.
Figure 2: Ranges of venomous snake species and number of medically important venomous snake species per 5 × 5 km location for which no effective therapy is currently listed by WHO
(A) Counts range from low (n=1) to high (n=13). The light grey areas represent locations where no medically important venomous snake species are present. (B) Counts range from low (n=1) to high
(n=7). The light grey areas represent locations where snake species present have effective therapies listed by WHO, and the dark grey areas represent locations where no medically important venomous
snake species are present.
Number of category one and two
snake species
High
Low
A
B
High
Low
Number of c
ategory one and two
snake species with no effective
therapy
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Pairing ecological measures with health system metrics
To identify the extent to which snakebites could vary
globally as a public health problem, we evaluated three
key dimensions: existence of any marketed antivenom
therapy, quality of health care and treatment options
available, and geographical accessibility to health care.
Of the 278 snakes considered, the WHO antivenoms
database documents that any form of antivenom (either
monospecific or polyvalent) exists for 159 species.20
Coupling this availability information with each species
range we identified the geographical distribution of
species with no listed antivenoms, stratified by WHO
category.
To address dierences in health-care quality and
therefore identify populations to whom treatment
options might not be available or eectively deployed,
we categorised countries or regions to identify
populations living within each decile of a composite
indicator measure of health care (ie, the HAQ Index).21
The HAQ Index provides a metric for national levels of
personal health-care access and quality, drawing from
mortality rates from 32 causes that are amenable to
health care. The Index uses risk-standardised cause-
specific mortality rates derived from the Global Burden
of Disease 2016 study,29 scaled to a common 0–100 value,
and aggregated using weights derived from a principal
component analysis. To construct deciles, countries
were ranked on the basis of the HAQ Index score, and
threshold values splitting countries into ten equally
sized groups were identified. Because of variable
numbers of administrative units, subnational locations
were not used to construct decile thresholds;
subnationals for which HAQ values were estimated
were assigned to the corresponding nationally derived
decile on the basis of their value. To evaluate the
appropriateness of the HAQ Index as a proxy metric for
severe snakebite-related outcomes, we analysed the
relationship between published estimates of snakebite-
specific mortality numbers and the index, mimicking
analyses undertaken on other development indices and
mortality outcomes.6
To reflect relative geographical isolation from health
care, we coupled mortality data with a contemporary
surface of accessibility to major population centres.
Habib and Abubakar30 identified that, for a Nigerian
cohort of cases, each hour delay between envenomation
and antivenom administration was associated with
an increased mortality outcome of 1·01% (95% CI
1·00–1·02).30 A contemporary surface of accessibility to
high-density urban locations (travel time in minutes to
locations with a population >50 000) was used to identify
remote populations and compared with the mortality
statistics above.22 To evaluate the suitability of a
population–centre-based metric versus a health-care-
focused measure, we did a sensitivity analysis using
published data for African health-care facilities.31
Populations living within these geographical regions of
vulnerability were enumerated using the most recent
gridded population estimates from WorldPop, producing
estimates at the 5 × 5 km pixel level, and aggregated to
each country’s second-level administrative division
aiding government interpretation.32
Data sharing
All codes used throughout this study are available at
https://github.com/joshlongbottom/snakebite.
Figure 3: Average travel time to nearest major city for populations living within snake ranges
The light grey areas represent locations without the presence of medically important venomous snake species.
Average travel time
24 h
0
h
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Role of the funding source
The funder of the study had no role in study design, data
collection, data analysis, data interpretation, or writing of
the report. The corresponding authors had full access to
all the data in the study and had final responsibility for
the decision to submit for publication.
Results
Through the combination of publicly available data, we
provide a surface showing the ranges of 278 snake
species per 5 × 5 km area globally. Our MESS validation
method resulted in range amendments of 96 species
(appendix 1). Given the broad distribution of snakes,
approximately 6·85 billion people live within the range
of one or more of the species considered (figure 2A).
When filtered by medical classification, 5·80 billion
people live within range of category one species and
5·53 billion people live within range of category
two species (appendix 2 pp 13, 14). Hotspots of venomous
snake diversity include the Congo Basin, southeast Asia,
and Latin America.
Using the only openly available database for antivenom
availability, we identified 119 (43%) of the 278 mapped
species with no specific therapy. Of these identified
species, 24 (20%) were category one importance and
95 (80%) were category two importance. Hotspots of
species with no listed antivenom occur throughout
west Africa (eg, Ghana has ≤7 species per cell),
central Africa (eg, Cameroon has ≤7 species per cell),
South America (eg, Colombia has ≤7 species per cell), and
south Asia (eg, India has ≤6 species per cell; figure 2B;
appendix 2 pp 15, 16). Among category one snake species
with no therapy, Myanmar and Bangladesh have the
highest number (≤3 species per cell), with areas in
west Africa (Mali, Senegal, and Guinea) and Namibia
having up to two therapy-naive species per cell.
Populations living within these ranges of snake species
vary greatly in terms of accessibility to population centres
and presumed health care. Although antivenoms are
deployed in health facilities of some countries with very
small communities, this deployment is not universal, and
in the absence of exact data for antivenom access, we
were required to approximate the influence of travelling
time to health-care facilities via a proxy of distance to
centres with more than 50 000 inhabitants. Our time-
delay surface highlights that should envenoming
occur in large areas of Sudan, Algeria, Indonesia,
Papua New Guinea, Colombia, and Peru, the time taken
to travel to a city in which we might expect to find available
treatment could worsen mortality outcomes by more than
25%, assuming linear scaling of the statistic from Habib
and Abubakar30 (figure 3). For instance, 2 531 665 people
(78·71% of the population) live within ranges of any snake
species within South Sudan and 624 204 people
(89·89% of the population) in Papua New Guinea live
more than 1 h from locations with 50 000 people or more
(appendix 2 pp 17–26); globally, 750·19 million people
(10·95% of the population) potentially at risk from
snakebite envenoming live more than 1 h from high-
density urban areas, increasing the likelihood of delay-
based mortality outcomes after envenoming.
Sensitivity analyses using African hospitals versus cities
similarly showed consistent results (appendix 2 pp 34, 35).
Separating the populations living within ranges of
species by HAQ Index deciles reveals large dieren ces
across the sociodemographic spectrum (figure 4).
Such dierences are best highlighted when analysing
populations by medical classification: approximately
389·58 million individuals (92·91%) of the population
within the lowest HAQ Index decile are at risk of exposure
to a category one snake compared with approximately 1·61
billion individuals (86·27%) within the highest decile
(appendix 2 p 16). Furthermore, 272·91 million individuals
(65·25%) of the population within the lowest decile are at
risk of exposure to any snake for which no eective
therapy exists compared with 519·46 million individuals
(27·79%) within the highest HAQ Index decile (figure 4).
Vulnerable populations (ie, people in geographical reg-
ions living within the range of any snake species who also
lived more than 3 h away from major urban centres, had
health systems that scored within the lowest three deciles
Figure 4: Proportion of populations living within range of snake species by each HAQ Index decile
(A) Populations living within the range of one or more medically important venomous snake species (either
category one or two). (B) Populations living within the range of one or more medically important venomous snake
species (either category one or two), for which no effective therapy is listed. HAQ=Healthcare Access and Quality.
1
0
Population (%)
HAQ Index decile HAQ Index decile
AB
20
40
60
80
100
2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10
Outside of rangeWithin range
Figure 5: Hotspots of vulnerable populations to medically important
venomous snake species
Hotspots are defined as people living in areas within the range of one or more
medically important venomous snake species, and more than 3 h away from
major urban centres with Healthcare Access and Quality Index deciles of 1–3.
(A) Pixel-level vulnerability surface (ie, vulnerability to all species of medically
important snakes). (B) Aggregated second administrative level vulnerability to
all species of medically important venomous snakes, as measured by the
absolute number of people. (C) Aggregated second administrative level
vulnerability to only those species for which no effective therapy is currently
listed by WHO, as measured by the absolute number of people.
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C
0
1–50
000
50
001–500
000
500
001–1
000
000
>1
000
001
Vulnerable populations
B
0
1–50
000
50
001–500
000
500
001–1
000
000
>1
000
001
Vulnerable populations
A
Vulnerable populations
Not vulnerable populations
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of the HAQ Index, and were further stratified by the
presence or absence of a WHO listed antivenom) are
highlighted in figure 5. Vulnerability estimates for HAQ
Index deciles of 1–10 are provided in the table. Within the
lowest three deciles, we highlighted regions where about
92·66 million vulnerable individuals live (table), with
Angola, Pakistan, Indonesia, Ethiopia, and the Democratic
Republic of the Congo ranking as the highest locations
in absolute numbers. The majority of countries across
Africa, many of which have some of the lowest scores on
the HAQ Index, have vulnerable populations present.
When excluding infor mation about the existence of
antivenoms, 146·70 million people live within remote
areas lacking quality health care provisioning (deciles 1–3;
appendix 2 pp 28–31).
Discussion
Understanding the distribution of venomous snakes and
their potential burden on health systems at national,
regional, and global levels is important for eective re-
duction and control of snakebite.8 By combining species
range maps, available information about antivenoms, and
measures of quality of and distance to health care, this
study provides global contemporary maps of vulnerable
populations to snakebite and its clinical complications.
This analysis, therefore, provides a means of identifying
communities in greatest need of support from herpe-
tologists, clinicians, and public health experts, and to
prioritise new data-collection activities.
Although this analysis is not a substitute for a full global
burden estimation, there is overlap between vulnerable
communities and existing burden estimates, with vulner-
able countries such as Nigeria, Benin, Congo (Brazzaville),
Myanmar, and Papua New Guinea identified as burden-
some in country-specific estimates,1 and south Asia and
sub-Saharan Africa as regions with considerable mort-
ality and morbidity.3 A post-hoc analysis of national
envenoming and death burden values, shows that, for
vulnerable countries, such values were more likely to be
estimates as opposed to data-driven numbers (χ² test at
90% significance level, p=0·0476 for envenoming and
p=0·0517 for deaths).3 Chippaux33 similarly shows that
where data are available in sub-Saharan countries, they
are not necessarily contemporary information. These
Decile 1 Decile 2 Decile 3 Decile 4 Decile 5 Decile 6 Decile 7 Decile 8 Decile 9 Decile 10
Afghanistan 281 586 ·· ·· ·· ·· ·· ·· ·· ·· ··
Algeria ·· ·· ·· ·· 74 397 ·· ·· ·· ·· ··
Angola ·· 3 652 123 ·· ·· ·· ·· ·· ·· ·· ··
Argentina ·· ·· ·· ·· ·· 78 462 ·· ·· ·· ··
Armenia ·· ·· ·· ·· ·· ·· 27 064 ·· ·· ··
Azerbaijan ·· ·· ·· ·· ·· 116 150 ·· ·· ·· ··
Bangladesh ·· ·· ·· 359 780 ·· ·· ·· ·· ·· ··
Belize ·· ·· ·· ·· 14 532 ·· ·· ·· ·· ··
Benin 97 491 ·· ·· ·· ·· ·· ·· ·· ·· ··
Bhutan ·· ·· ·· 114 385 ·· ·· ·· ·· ·· ··
Bolivia ·· ·· ·· 1 307 831 ·· ·· ·· ·· ·· ··
Botswana ·· ·· ·· 323 599 ·· ·· ·· ·· ·· ··
Brazil ·· ·· ·· ·· 4 107 300 2296 619 ·· ·· ··
Brunei ·· ·· ·· ·· ·· ·· ·· 9630 ·· ··
Burkina Faso 699 570 ·· ·· ·· ·· ·· ·· ·· ·· ··
Burundi 10 597 ·· ·· ·· ·· ·· ·· ·· ·· ··
Cambodia ·· ·· 43 972 ·· ·· ·· ·· ·· ·· ··
Cameroon ·· 1 279 030 ·· ·· ·· ·· ·· ·· ·· ··
Central African
Republic
1 081 841 ·· ·· ·· ·· ·· ·· ·· ·· ··
Chad 5814 ·· ·· ·· ·· ·· ·· ·· ·· ··
China ·· ·· ·· 167 314 6 787 216 6 793 121 11 323 668 8 414 197 14 142 ··
Colombia ·· ·· ·· ·· ·· 6 277 835 ·· ·· ·· ··
Congo
(Brazzaville)
·· 521 800 ·· ·· ·· ·· ·· ·· ·· ··
Costa Rica ·· ·· ·· ·· ·· ·· 138 011 ·· ·· ··
Côte d’Ivoire 379 448 ·· ·· ·· ·· ·· ·· ·· ·· ··
Democratic
Republic of the
Congo
22 586 819 ·· ·· ·· ·· ·· ·· ·· ·· ··
Djibouti ·· 73 050 ·· ·· ·· ·· ·· ·· ·· ··
(Table continues on next page)
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9
Decile 1 Decile 2 Decile 3 Decile 4 Decile 5 Decile 6 Decile 7 Decile 8 Decile 9 Decile 10
(Continued from previous page)
Ecuador ·· ·· ·· ·· 552 572 ·· ·· ·· ·· ··
Egypt ·· ·· ·· ·· 37 780 ·· ·· ·· ·· ··
Equatorial
Guinea
·· ·· ·· 242 345 ·· ·· ·· ·· ·· ··
Eritrea 905 464 ·· ·· ·· ·· ·· ·· ·· ·· ··
Ethiopia 10 422 734 ·· ·· ·· ·· ·· ·· ·· ·· ··
Gabon ·· ·· 499 707 ·· ·· ·· ·· ·· ·· ··
Georgia ·· ·· ·· ·· ·· 111 973 ·· ·· ·· ··
Ghana ·· ·· 354 713 ·· ·· ·· ·· ·· ·· ··
Greece ·· ·· ·· ·· ·· ·· ·· ·· 7327 ··
Guatemala ·· ·· ·· 533 186 ·· ·· ·· ·· ·· ··
Guinea 427 253 ·· ·· ·· ·· ·· ·· ·· ·· ··
Guinea-Bissau 120 745 ·· ·· ·· ·· ·· ·· ·· ·· ··
Guyana ·· ·· ·· 138 904 ·· ·· ·· ·· ·· ··
Honduras ·· ·· ·· 58 882 ·· ·· ·· ·· ·· ··
India ·· 231 656 1 488 560 4 623 346 ·· 276 547 ·· ·· ·· ··
Indonesia ·· ·· 10 454 226 ·· ·· ·· ·· ·· ·· ··
Iran ·· ·· ·· ·· ·· ·· 341 174 ·· ·· ··
Iraq ·· ·· ·· 49 668 ·· ·· ·· ·· ·· ··
Japan ·· ·· ·· ·· ·· ·· ·· ·· 38 825 6288
Jordan ·· ·· ·· ·· ·· ·· 91 671 ·· ·· ··
Kazakhstan ·· ·· ·· ·· ·· ·· 2 494 396 ·· ·· ··
Kenya ·· ·· 1 825 765 ·· ·· ·· ·· ·· ·· ··
Kyrgyzstan ·· ·· ·· ·· 495 765 ·· ·· ·· ·· ··
Laos ·· ·· 18 010 ·· ·· ·· ·· ·· ·· ··
Liberia ·· 664 940 ·· ·· ·· ·· ·· ·· ·· ··
Malawi ·· 133 687 ·· ·· ·· ·· ·· ·· ·· ··
Malaysia ·· ·· ·· ·· ·· 1 790 903 ·· ·· ·· ··
Mali ·· 2 373 844 ·· ·· ·· ·· ·· ·· ·· ··
Mauritania ·· ·· 5129 ·· ·· ·· ·· ·· ·· ··
Mexico ·· ·· ·· ·· 229 259 384 600 275 250 ·· ·· ··
Morocco ·· ·· ·· ·· 93 028 ·· ·· ·· ·· ··
Mozambique 3 206 555 ·· ·· ·· ·· ·· ·· ·· ·· ··
Myanmar ·· ·· 2 544 010 ·· ·· ·· ·· ·· ·· ··
Namibia ·· ·· 752 476 ·· ·· ·· ·· ·· ·· ··
Nepal ·· ·· 2 665 443 ·· ·· ·· ·· ·· ·· ··
Nicaragua ·· ·· ·· ·· 73 046 ·· ·· ·· ·· ··
Niger 15 45 113 ·· ·· ·· ·· ·· ·· ·· ·· ··
Nigeria ·· ·· 2 067 928 ·· ·· ·· ·· ·· ·· ··
Oman ·· ·· ·· ·· ·· ·· ·· 84 388 ·· ··
Pakistan ·· ·· 4 425 880 ·· ·· ·· ·· ·· ·· ··
Panama ·· ·· ·· ·· ·· 137 946 ·· ·· ·· ··
Paraguay ·· ·· ·· ·· 227 331 ·· ·· ·· ·· ··
Peru ·· ·· ·· ·· ·· 2 674 949 ·· ·· ·· ··
Philippines ·· ·· ·· 1 517 133 ·· ·· ·· ·· ·· ··
Russia ·· ·· ·· ·· ·· ·· ·· 1 205 085 ·· ··
Rwanda ·· ·· 32 081 ·· ·· ·· ·· ·· ·· ··
Saudi Arabia ·· ·· ·· ·· ·· ·· ·· 2 392 280 ·· ··
Senegal ·· 467 056 ·· ·· ·· ·· ·· ·· ·· ··
Sierra Leone 154 596 ·· ·· ·· ·· ·· ·· ·· ·· ··
Somalia 2 140 834 ·· ·· ·· ·· ·· ·· ·· ·· ··
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maps collate ecological and public health metrics, and
identify opportunities where substantial improvements
and refinements can be undertaken to move from
broad vulnerability assessment to a more nuanced
and accurate description of the most burdensome
populations.
Our study had key limitations, and future eorts can
focus on addressing some of these limitations: the relative
contribution of dierent snake species must be quantified,
the factors influencing snake–human interactions and
subsequent likelihood of envenoming events must be
identified, and snakebite-specific measures of local
preparedness, eectiveness, and coverage of existing
clinical countermeasures must be taken. Paucity of data
available at the global scale, despite comprehensive
coverage in several high-income countries, remains one
of the largest limitations throughout this study. Ultimately,
quantifying these additional components will allow for
estimates to be based on a bottom-up data synthesis,
rather than dependence on global-level datasets and
correlations.
Mapping snake species’ locations to reflect variations in
snake presence is also important. Fine-scale maps, such as
those of American venomous snake species,34 should be
extended globally—this current analysis identifies
216 species requiring updated assessments of current
ranges given the quality and quantity of records available.
This study also establishes a systematic prioritisation
based on medical importance (appendix 2 pp 3–11).
Although species occurrence surveys can be formally
done by public health initiatives or during ecological
assessments, citizen science has a complementary role
in facilitating broad-scale data collection.35
This assessment considers the presence of any one
venomous snake as a prerequisite for vulnerability;
however, dierent species contribute dierently to
envenoming risk. Species with a very high incidence of
envenoming events might be the dominant cause of high
snakebite burden in a locality,36 regardless of the presence
of other species,37 as reported for Echis ocellatus,38 Daboia
russelii,39 and others.40 Identifying and quantifying, at a
local scale, important species, risky human practices,
and ongoing changes to subsequent interactions given
climatic and socioeconomic change, are necessary.41
Future vulnerability assessments can explicitly leverage
interspecies’ dierences and weigh their relative
Decile 1 Decile 2 Decile 3 Decile 4 Decile 5 Decile 6 Decile 7 Decile 8 Decile 9 Decile 10
(Continued from previous page)
South Africa ·· ·· ·· 289 322 ·· ·· ·· ·· ·· ··
South Sudan 601 410 ·· ·· ·· ·· ·· ·· ·· ·· ··
Sri Lanka ·· ·· ·· ·· ·· ·· 62 951 ·· ·· ··
Sudan ·· ·· ·· 542 183 ·· ·· ·· ·· ·· ··
Suriname ·· ·· ·· 94 635 ·· ·· ·· ·· ·· ··
Swaziland ·· ·· 226 ·· ·· ·· ·· ·· ·· ··
Syria ·· ·· ·· ·· ·· 48 738 ·· ·· ·· ··
Tajikistan ·· ·· ·· 301 870 ·· ·· ·· ·· ·· ··
Tanzania ·· 4 950 775 ·· ·· ·· ·· ·· ·· ·· ··
Thailand ·· ·· ·· ·· ·· ·· 77 295 ·· ·· ··
The Gambia ·· 3245 ·· ·· ·· ·· ·· ·· ·· ··
Togo ·· 14 488 ·· ·· ·· ·· ·· ·· ·· ··
Trinidad and
Tobago
·· ·· ·· ·· ·· 6520 ·· ·· ·· ··
Turkey ·· ·· ·· ·· ·· ·· 48 653 ·· ·· ··
Uganda ·· 371 059 ·· ·· ·· ·· ·· ·· ·· ··
Ukraine ·· ·· ·· ·· ·· ·· ·· 4956 ·· ··
USA ·· ·· ·· ·· ·· ·· ·· ·· 4728 ··
Uzbekistan ·· ·· ·· ·· 805 059 ·· ·· ·· ·· ··
Venezuela ·· ·· ·· ·· ·· 3 3465 88 ·· ·· ·· ··
Vietnam ·· ·· ·· ·· 175 519 ·· ·· ·· ·· ··
Yemen ·· ·· 3 017 147 ·· ·· ·· ·· ·· ·· ··
Zambia 2 125 572 ·· ·· ·· ·· ·· ·· ·· ·· ··
Zimbabwe ·· 936 801 ·· ·· ·· ·· ·· ·· ·· ··
Total 46 793 442 15 673 554 30 195 273 10 664 383 13 672 804 22 046 628 14 880 752 12 110 536 65 022 6288
Country-level count of vulnerable people living within the range of one or more medically important venomous snake species, for which no effective therapy exists, and with a travel time of more than 3 h from
urban centres with a population of 50 000 people or more provided per HAQ Index decile (ranging from 1 [low] to 10 [high]). Appendix 2 shows the vulnerability estimates not incorporating antivenom
availability. HAQ=Healthcare Access and Quality.
Table: Vulnerable population count per HAQ Index decile
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11
contribution as a function of species-specific envenoming
risk and associated burden. The transition of the
WHO resource20 into a living database documenting
contemporary antivenom availability, species taxonomic
changes, higher-resolution distribution data, and other
information will substantially aid in this eort.42,43
Areas where snakes are present can be further evaluated
to determine the true incidence of envenoming events.
Local-scale household surveys assessing incidence of
snakebite have been done in several countries.11,14,15,44
Questions relating to snakebite could also be nested within
existing demographic and health surveys,45 minimising
associated costs and informing current data-poor
estimates. By integrating preventive measures with
existing management systems for neglected tropical
diseases, many logistical obstacles to eective intervention
might be overcome.46 Corresponding quantification of key
risky behaviours will help reflect fine-scale population
heterogeneity to exposure. Surveys such as the World Bank
Living Standards Measurement Survey series could be
used to obtain local-scale information about agricultural
practices,47 further aiding the identification of communities
most at risk and increasing understanding of the public
health consequences of dierent land use. Through these
steps, eorts to prevent envenoming events can be tailored
to the specifics of any given population.
In many low-income and middle-income countries, a
multitude of barriers influence snakebite outcomes
including health care, transport, and communications
infrastructure, along with adequacy of and access to safe,
eective, and aordable antivenom supplies, medical
sta proficiency and training, and public health policy.
When considering antivenom availability, this method is
constrained to listings as reported by WHO.20 Since
initial compilation, new antivenoms have become
available (eg, EchiTAb-Plus-ICP),48 while others have
ceased production (eg, Fav-Afrique by Sanofi).42 Market
availability of antivenom products does not translate to
in-field availability and ecacy; further information
regarding country-specific, contemporary stockpiles, and
the positioning of antivenom holding centres is required.
Given that some of the countries with the lowest
HAQ Index deciles have the largest proportions of the
population living in areas with snakes for which no
antivenom is currently reported, documented socio-
economic dierences might amplify inequalities in care.6
Although health system indicators and accessibility
metrics act as generalised correlates for a location’s
ability to respond to cases, these measures will possibly
underestimate or overstate local vulnerabilities in some
settings. Existing analyses of health systems show
variation both nationally and subnationally in treatment-
seeking behaviours,49,50 quality of primary point of care
visits and referrals,51 and general practitioner knowledge
about the condition.52 However, the external validity of
these existing surveys is unknown. This vulnerability
analysis provides a foundation for the identification of
locations where further surveys of treatment-seeking
behaviours, quality of care, and existing coverage of
antivenom stockpiles and supply chains need to be
assessed.
The global burden of snakebite can be assessed through
an approach that integrates ecological information, human
behavioural data, and snakebite-specific health system
functioning. The impetus to reduce and control the burden
of snakebite envenoming, a thorough cataloguing of snake
presence and abundance, species-specific interaction
profiles with humans, and detailed understanding of
logistical hurdles to intervention delivery should be
long-term objectives. Contemporary assessments, such as
the resources presented, provide an immediate means of
identifying key hotspots and most vulnerable communities
where the need for such investigations is greatest.
Contributors
JL, SIH, and DMP conceived and planned the study. JL wrote the
computer code, and designed and did the analyses with input from
FMS and DMP. DJWe constructed the accessibility covariate data layer.
JL produced all output figures. NR, DAW, RRdC, and DJWi provided
intellectual input into aspects of this study. All authors contributed to the
interpretation of the results. JL wrote the first draft of the manuscript
and all authors contributed to subsequent revisions.
Declaration of interests
We declare no competing interests.
Acknowledgments
This study is funded by the Bill & Melinda Gates Foundation. SIH is
funded by grants from the Bill & Melinda Gates Foundation
(OPP1132415), the Wellcome Trust (209142 and Senior Research
Fellowship 095066), and the Fleming Fund. The Bill & Melinda Gates
Foundation grant OPP1093011 supports JL and DMP. The Fleming
Fund also supports MD. FMS is supported by a scholarship from
The Rhodes Trust. GA, FC, NR, and RRdC are partly supported by a
grant from the Swiss National Science Foundation (315130_176271).
DJWi is supported by a Doherty Biomedical Postdoctoral Fellowship
from the Australian National Health and Medical Research Council.
We thank C A Design Services for assistance with expert opinion range
map digitisation.
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... The treatment of snakebite envenoming (SBE) is an urgent, global unmet medical need. It is estimated that worldwide more than 2.7 million SBEs occur annually, causing significant morbidity (~400,000 permanent deformities or amputations) and mortality (~138,000 deaths), primarily among poor, rural populations of low-and middle-income countries [1][2][3]. Approximately 5.8 billion people live in regions that place them at risk for being bitten by medically important snakes. An estimated 75 percent of deaths from SBE occur outside the hospital setting before victims can reach adequate medical care [3,4] and poor outcomes are associated with delays in care [5][6][7]. ...
... Approximately 5.8 billion people live in regions that place them at risk for being bitten by medically important snakes. An estimated 75 percent of deaths from SBE occur outside the hospital setting before victims can reach adequate medical care [3,4] and poor outcomes are associated with delays in care [5][6][7]. A staggering 1.2 million snakebite deaths, 325,000 (28%) in children younger than 15 years of age, and loss of more than 3 million disability-adjusted life years are estimated to have occurred in India alone from 2000 to 2019 [8]. ...
... The classification of snakebite envenoming as a Neglected Tropical Disease (NTD) by the World Health Organization (WHO) has underscored the urgency of the global health crisis posed by SBE [3]. WHO has established a multifaceted global strategy to improve the control, prevention, and treatment of SBE, including the development of new therapeutic approaches to treatment [14]. ...
Article
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Introduction: Snakebite is an urgent, unmet global medical need causing significant morbidity and mortality worldwide. Varespladib is a potent inhibitor of venom secretory phospholipase A2 (sPLA2) that can be administered orally via its prodrug, varespladib-methyl. Extensive preclinical data support clinical evaluation of varespladib as a treatment for snakebite envenoming (SBE). The protocol reported here was designed to evaluate varespladib-methyl for SBE from any snake species in multiple geographies. Methods and analysis: BRAVO (Broad-spectrum Rapid Antidote: Varespladib Oral for snakebite) is a multicenter, randomized, double-blind, placebo-controlled, phase 2 study to evaluate the safety, tolerability, and efficacy of oral varespladib-methyl plus standard of care (SoC) vs. SoC plus placebo in patients presenting with acute SBE by any venomous snake species. Male and female patients 5 years of age and older who meet eligibility criteria will be randomly assigned 1:1 to varespladib-methyl or placebo. The primary outcome is the Snakebite Severity Score (SSS) that has been modified for international use. This composite outcome is based on the sum of the pulmonary, cardiovascular, nervous, hematologic, and renal systems components of the updated SSS. Ethics and dissemination: This protocol was submitted to regulatory authorities in India and the US. A Clinical Trial No Objection Certificate from the India Central Drugs Standard Control Organisation, Drug Controller General-India, and a Notice to Proceed from the US Food and Drug Administration have been obtained. The study protocol was approved by properly constituted, valid institutional review boards or ethics committees at each study site. This study is being conducted in compliance with the April 1996 ICH Guidance for Industry GCP E6, the Integrated Addendum to ICH E6 (R2) of November 2016, and the applicable regulations of the country in which the study is conducted. The trial is registered on Clinical trials.gov, NCT#04996264 and Clinical Trials Registry-India, 2021/07/045079 000062.
... This is due to the agricultural and other rural practices and socioeconomic status, which largely contribute to increased human-snake interactions (Harrison et al., 2009). Longbottom et al. (2018) carried out a global mapping of hotspots with vulnerability to snakebite envenomation and showed that an overlap exists between identified vulnerable communities and existing burden estimates ( Figure 1). Benin, Congo (Brazzaville), Nigeria, Myanmar, and Papua New Guinea, previously estimated to be burdensome countries (Chippaux, 1998), are identified as vulnerable communities. ...
... (B) Aggregated second administrative level vulnerability all species of medically important venomous snakes, as measured by the absolute number of people. Source: Longbottom et al. (2018) Antivenoms Snake antivenom (also referred to as antivenin, venom antiserum or antivenom immunoglobulin) is a drug used to treat snakebites and wounds. The administration of antivenoms has been the basis for the treatment of snakebite for almost 125 years (Potet et al., 2021). ...
Article
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Snakes are primarily venomous animals that bite when frightened, which can be lethal. This is because snake venom is one of the most active biological fluids containing a wide range of peptides and proteins that can induce several effects, including hemo-, neuro-, cyto-and myotoxic effects, consequently becoming deleterious to life if untreated. Although snakes are found on almost all continents, the rural communities in sub-Saharan Africa are the most affected by snakebites, mainly due to increased human-snake interactions forced by their socioeconomic status and agricultural or rural practices. Consequently, this recently prompted the World Health Organisation to enlist snakebites envenoming among the category-A neglected tropical diseases with an estimated annual death of 7,300 in sub-Saharan Africa. Aside from mortality, snakebite envenomation also causes permanent disabilities in humans and a heavy burden on livestock, creating economic hardship for the already impoverished communities. Several animal-derived antivenoms have been developed for treating snakebites and wounds; they effectively attenuate venom-related toxicity, tissue necrosis, and deaths. However, despite the efficacy of these antivenoms, several issues, such as problems in production and distribution, exorbitant prices, and adverse effects of the antivenoms, have challenged their practical use in sub-Saharan Africa. This review highlights the challenges that make conventional antivenoms unavailable to prone populations. We also discuss the plants used in the treatment of snake bites laying emphasis on Mucuna pruriens (Velvet bean) and Allium sativum (Garlic) as the two most studied medicinal plants. The progress and bottlenecks of using herbal antivenoms as alternatives in treating snakebite envenomation in sub-Saharan Africa are also discussed.
... Encompassing Central and South America, it is home to about 900 snake species [2,41]. As a consequence of this remarkable ophidian diversity, the Neotropics are a global hotspot of medically important snake species, for many of which no effective therapy is listed by the WHO (like the Congo Basin and southeast Asia [3]), and which pose a serious threat to the large part of the local population, leading a markedly rural lifestyle [12,42,43]. In recent years, various research centres and laboratories located in Central and South America (e.g., Instituto Butantan in Brazil, Instituto Clodomiro Picado in Costa Rica) have made a remarkable contribution to snakebite studies [37,38], largely focusing on local medically relevant snake species. ...
... Nevertheless, we were able to detect an increase in the curves relative to these categories starting from the first half of the 2010s (see Figure 6). This is concordant with several publications and awareness campaigns which, together with the very recent official recognition of snakebite as a neglected tropical disease by the World Health Organization [53], have recently been addressing the human health burden of snakebite and the antivenom crisis [3,10,12,37,54], renewing the interest in snake venom research in general and likely stimulating the study of these topics. ...
Article
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Biases in snake venom research have been partially identified but seldomly quantified. Using the Google Scholar web search engine, we collected a total of 267 articles published between 1964 and 2021, and reviewed them to assess the main trends in this field of study. We developed a 4-category classification of the harmful potential of each of the 298 snake species retrieved from the analysed publications, and tested whether taxonomy, realm of origin, and/or assigned hazard category could affect how often each of them appeared in the articles considered. Overall, viperids were significantly more represented than any other snake taxon retrieved. The Neotropics were the most represented biogeographic realm for number of studied species, whereas information about the country of origin of the analysed specimens was often incomplete. The vast majority of the publications focused on snake venom characterisation, whereas more ecology-related topics were rarely considered. Hazard category and biogeographic realm of origin of each species had a significant effect on the number of articles dedicated to it, suggesting that a snake’s harmful potential and place of origin influence its popularity in venom studies. Our analysis showed an overall positive trend in the number of snake venom studies published yearly, but also underlined severe neglect of snake families of supposedly minor medical relevance (e.g., Atractaspididae), underrepresentation of some of the areas most impacted by snakebite (i.e., Indomalayan and Afrotropic realms), and limited interest in the ecological and functional context of snake venom.
... Identifying area with high risk of snakebite can help us to identify target areas for awareness rising program and to effectively provide antivenoms to the most vulnerable groups (Longbottom et al., 2018;Pintor et al., 2021;Youse et al., 2020). However, our knowledge on snakebite risk pattern still remains limited (Pintor et al., 2021;Ruiz de Castañeda et al., 2022). ...
Preprint
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Snakebite is a global health problem and yearly snakebites have been estimated up to 5 million leading to about 100,000 deaths each year. While those numbers are showing that snakebite is one of the largest risks from wildlife, little is known about venomous snake distribution, spatial variation in snakebite risk, potential changes in snakebite risk pattern due to climate change, and vulnerable human population. As a consequence, management and prevention of snakebite is hampered by this lack of information. Previous studies suggest that habitat suitability models are effective tools in predicting snakebite risk areas under current and future climate and identifying vulnerable human population. Here we used an ensemble approach of five different habitat suitability modeling algorithms for 10 medically important venomous snakes to quantify snakebite risk pattern, map snakebite hotspots, calculate community composition changes and changes in vulnerability to snakebite in Iran under current and future climate (years 2041–2070 and 2071–2100). We identified areas with high snakebite risk in Iran and showed that snakebite risk will increase in some parts of the country. We also found mountainous areas (Zagros, Alborz, Kopet-Dagh mountains) will experience highest changes in species composition. We underline that in order to improve snakebite management, areas which were identified with high snakebite risk in Iran need to be prioritized for the distribution of antivenom medication and awareness rising programs among vulnerable human population.
... Snake communities are usually comprised of species occupying several size classes and trophic levels (Sosa and Schalk 2016;Zipkin et al. 2020). Often these include top predators, which can act as indicators of environmental health (Beaupre and Douglas 2009; Sergio et al. 2008); and, where medically significant venomous species occur, snakebite can contribute a significant burden on human health systems (Chippaux 2017;Longbottom et al. 2018;Williams et al. 2019). Theoretically, larger snake species may be more prone to success in urban environments, as they generally have higher fecundity and larger home ranges, and the ability to exploit a wider variety of prey (Iverson 1987;Shine et al. 1998;Tamburello et al. 2015). ...
Article
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Urbanisation changes landscapes, often simplifying and homogenising natural ecosystems while introducing novel environments. Although this transformation often adversely impacts native wildlife, generalist species that exhibit broad dietary and habitat requirements can persist and take advantage of urban environments. To understand which life history traits most influence the occurrence of a diverse snake assemblage in an urban environment, we leveraged a dataset of 5102 detection records for 12 snake species in the tropical city of Darwin, Australia. By building ecological niche models, calculating urban niche hypervolume, and compiling life history data, we analysed the diversity of environments occupied by each species and determined which landscape components were most associated with occurrence data. In keeping with our hypothesis that generalist species would be more successful, we found that species with broader habitat and dietary preferences, as well as a penchant for arboreality, were associated with larger urban niche hypervolumes and more frequent human–snake interactions. Additionally, we found that colubrid snakes had significantly larger urban niche hypervolumes than elapid species. These findings contribute to understanding how life history traits aid wildlife persistence in, and adaptation to, urban ecosystems, and have implications for landscape design and conservation management.
... Besides, there are also most cited topics such as the discussion of financial literacy as a part of economic literacy by S. Cole [21], and the discussion of mathematical literacy as a part of basic literacy by K. Stacey [22]. In addition to this, the most widely cited articles discussing topics outside of digital-age literacy are such as research on poisonous snake bites by J. Longbottom et al [23], substitutes for science learning by PWU Chinn [24], global primate conservation by Estrada [25], and the effects of peatland fires by Carmenta [26]. ...
Conference Paper
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This research was conducted to determine research development and describe research opportunities on digital-age literacy in Indonesia. Data in journals and proceedings were collected from the Scopus database using search keywords sourced from the main domain of digital-age literacy and other related keywords from 2003-2020. The data collected were 681 articles in the form of 453 journal articles and 228 proceedings. The analysis was carried out using Ms. Excel and VOSViewer. Ms. Excel analyzes the number of publications, author productivity, and the topmost cited articles. In contrast, VOSViewer is used to create and analyze visualizations based on words, known as co-occurrence and co-authorship, to determine the relationship between authors. The results showed that a significant increase in the number of publications occurred from 2018-2020, where the highest publication occurred in 2020, which was 33.63%. Researcher productivity is almost the same, between 1-3 publications. The most cited topics were global awareness, economic literacy, basic literacy, and several articles discussing topics outside digital-age literacy. Network visualization co-occurrence is divided into 10 clusters. The latest topics based on article data in this study include STEM, covid, and higher education published in 2019-2020. The most frequently researched topics are related to students, followed by financial literacy, ICT, media literacy, culture, and higher education. The co-authorship visualization shows no collaboration between researchers.
... En el ámbito de Guatemala, ocurren alrededor de 900 casos por año, la mayoría en los departamentos de Petén, Alta Verapaz y Escuintla (Guerra-Centeno, 2018a). Los campesinos jóvenes son los más afectados (Guerra-Centeno, 2016) y los más vulnerables desde múltiples dimensiones (Guerra-Centeno, 2017;Longbottom et al., 2018). ...
Article
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Con el propósito de comprender los significados de las prácticas populares de prevención y tratamiento del accidente ofídico en Petén, Guatemala se realizó una investigación cualitativa por el método fenomenológico. Se entrevistaron a profundidad 10 participantes campesinos de las aldeas El Caoba y San Andrés. Se identificaron ocho categorías descriptivas: (1) Matar a la serpiente por prevención (2) El intento de extracción del veneno, (3) La aplicación de torniquete, (4) La ingestión de brebajes, (5) La aplicación de sustancias en la herida, (6) La inyección de suero antiofídico en el campo, (7) Valor y actitud positiva, (8) Prohibición moral de tomar agua. Los hallazgos del presente estudio idiográfico indican que la noción de la venenosidad de las serpientes ocupa un lugar muy importante en el imaginario de la gente del campo y que la persona víctima de accidente ofídico echa mano de varios recursos en su carrera por la supervivencia.
... Snakebite envenoming (SBE) is a high-priority neglected tropical disease that predominantly affects rural communities living in low-and middle-income countries in Asia, Latin America, and Africa (Gutiérrez et al., 2017;. SBE causes around 140,000 deaths and 500,000 permanent disabilities annually worldwide (Kasturiratne et al., 2008;Longbottom et al., 2018). Notably, SBE instigates substantial socioeconomic impacts on victims, their families and society through resulting consequences including deaths, permanent disabilities, psychological morbidity, and significant treatment cost (Vaiyapuri et al., 2013;Franco et al., 2022). ...
Article
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Snakebite envenoming (SBE) predominantly affects rural impoverished communities that have limited access to immediate healthcare. These communities often hold numerous myths/misbeliefs about snakes and SBE. Moreover, healthcare professionals who practice in rural regions often work in unstable situations with limited medical infrastructure and therefore, lack sufficient knowledge/experience and confidence in the clinical management of SBE. Due to the lack of reliable statistics on the true burden of SBE, developing health policies for this condition by relevant authorities may be difficult. Hence, it is critical to improve awareness about SBE among rural communities, healthcare professionals and health authorities using robust multifaceted community health education approaches. Here, we describe the design, development, implementation, and impact of distinctive community health education approaches that we used in India and Brazil. A wide range of educational tools including information leaflets, posters, pocket guides, learning materials for healthcare professionals and short/long video documentaries were developed in local languages and used to engage with target communities through direct assemblies as well as mass/traditional and social media. Notably, we used diverse methods to determine the impact of our programs in improving awareness, treatment-seeking behaviour, and clinical practice. The people-centred approaches that we used were inclusive and highly impactful in instigating fundamental changes in the management of SBE among rural communities. The resources and approaches presented in this article can be easily adapted for wider use in other countries in order to collectively reduce SBE-induced deaths, disabilities and socioeconomic ramifications.
Technical Report
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MALAYSIAN SOCIETY ON TOXINOLOGY NEWSLETTER DUO EDITION 2021-2022
Article
Snakebite affects more than 1.8 million people annually. Factors explaining snakebite variability include farmers’ behaviors, snake ecology and climate. One unstudied issue is how farmers’ adaptation to novel climates affect their health. Here we examined potential impacts of adaptation on snakebite using individual-based simulations, focusing on strategies meant to counteract major crop yield decline due to changing rainfall in Sri Lanka. For rubber cropping, adaptation led to a 33% increase in snakebite incidence per farmer work hour due to work during risky months, but a 17% decrease in total annual snakebites due to decreased labour in plantations overall. Rice farming adaptation decreased snakebites by 16%, due to shifting labour towards safer months, while tea adaptation led to a general increase. These results indicate that adaptation could have both a positive and negative effect, potentially intensified by ENSO. Our research highlights the need for assessing adaptation strategies for potential health maladaptations.
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Background: A key component of achieving universal health coverage is ensuring that all populations have access to quality health care. Examining where gains have occurred or progress has faltered across and within countries is crucial to guiding decisions and strategies for future improvement. We used the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) to assess personal health-care access and quality with the Healthcare Access and Quality (HAQ) Index for 195 countries and territories, as well as subnational locations in seven countries, from 1990 to 2016. Methods: Drawing from established methods and updated estimates from GBD 2016, we used 32 causes from which death should not occur in the presence of effective care to approximate personal health-care access and quality by location and over time. To better isolate potential effects of personal health-care access and quality from underlying risk factor patterns, we risk-standardised cause-specific deaths due to non-cancers by location-year, replacing the local joint exposure of environmental and behavioural risks with the global level of exposure. Supported by the expansion of cancer registry data in GBD 2016, we used mortality-to-incidence ratios for cancers instead of risk-standardised death rates to provide a stronger signal of the effects of personal health care and access on cancer survival. We transformed each cause to a scale of 0–100, with 0 as the first percentile (worst) observed between 1990 and 2016, and 100 as the 99th percentile (best); we set these thresholds at the country level, and then applied them to subnational locations. We applied a principal components analysis to construct the HAQ Index using all scaled cause values, providing an overall score of 0–100 of personal health-care access and quality by location over time. We then compared HAQ Index levels and trends by quintiles on the Socio-demographic Index (SDI), a summary measure of overall development. As derived from the broader GBD study and other data sources, we examined relationships between national HAQ Index scores and potential correlates of performance, such as total health spending per capita. Findings: In 2016, HAQ Index performance spanned from a high of 97·1 (95% UI 95·8–98·1) in Iceland, followed by 96·6 (94·9–97·9) in Norway and 96·1 (94·5–97·3) in the Netherlands, to values as low as 18·6 (13·1–24·4) in the Central African Republic, 19·0 (14·3–23·7) in Somalia, and 23·4 (20·2–26·8) in Guinea-Bissau. The pace of progress achieved between 1990 and 2016 varied, with markedly faster improvements occurring between 2000 and 2016 for many countries in sub-Saharan Africa and southeast Asia, whereas several countries in Latin America and elsewhere saw progress stagnate after experiencing considerable advances in the HAQ Index between 1990 and 2000. Striking subnational disparities emerged in personal health-care access and quality, with China and India having particularly large gaps between locations with the highest and lowest scores in 2016. In China, performance ranged from 91·5 (89·1–93·6) in Beijing to 48·0 (43·4–53·2) in Tibet (a 43·5-point difference), while India saw a 30·8-point disparity, from 64·8 (59·6–68·8) in Goa to 34·0 (30·3–38·1) in Assam. Japan recorded the smallest range in subnational HAQ performance in 2016 (a 4·8-point difference), whereas differences between subnational locations with the highest and lowest HAQ Index values were more than two times as high for the USA and three times as high for England. State-level gaps in the HAQ Index in Mexico somewhat narrowed from 1990 to 2016 (from a 20·9-point to 17·0-point difference), whereas in Brazil, disparities slightly increased across states during this time (a 17·2-point to 20·4-point difference). Performance on the HAQ Index showed strong linkages to overall development, with high and high-middle SDI countries generally having higher scores and faster gains for non-communicable diseases. Nonetheless, countries across the development spectrum saw substantial gains in some key health service areas from 2000 to 2016, most notably vaccine-preventable diseases. Overall, national performance on the HAQ Index was positively associated with higher levels of total health spending per capita, as well as health systems inputs, but these relationships were quite heterogeneous, particularly among low-to-middle SDI countries. Interpretation: GBD 2016 provides a more detailed understanding of past success and current challenges in improving personal health-care access and quality worldwide. Despite substantial gains since 2000, many low-SDI and middle-SDI countries face considerable challenges unless heightened policy action and investments focus on advancing access to and quality of health care across key health services, especially non-communicable diseases. Stagnating or minimal improvements experienced by several low-middle to high-middle SDI countries could reflect the complexities of re-orienting both primary and secondary health-care services beyond the more limited foci of the Millennium Development Goals. Alongside initiatives to strengthen public health programmes, the pursuit of universal health coverage hinges upon improving both access and quality worldwide, and thus requires adopting a more comprehensive view—and subsequent provision—of quality health care for all populations.
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Background Snakebite envenoming causes considerable morbidity and mortality in northern Nigeria. The clinician’s knowledge of snakebite impacts outcome. We assessed clinicians’ knowledge of snakebite envenoming to highlight knowledge and practice gaps for possible intervention to improve snakebite outcomes. Methods This was a cross-sectional multicentre study of 374 doctors selected from the accident and emergency, internal medicine, family medicine/general outpatient, paediatrics and surgery departments of nine tertiary hospitals in northern Nigeria using a multistage sampling technique. A self-administered questionnaire was used to assess their sociodemographics, knowledge of common venomous snakes, snakebite first aid, snake antivenom treatment and prevention. Results The respondents’ mean age was 35.6±5.8 y. They were predominantly males (70.6%) from urban hospitals (71.9%), from the northwest region (35.3%), in family medicine/general outpatient departments (33.4%), of <10 years working experience (66.3%) and had previous experience in snakebite management (78.3%). Although their mean overall knowledge score was 70.2±12.6%, only 52.9% had an adequate overall knowledge score. Most had adequate knowledge of snakebite clinical features (62.3%), first aid (75.7%) and preventive measures (97.1%), but only 50.8% and 25.1% had adequate knowledge of snake species that caused most injuries/deaths and anti–snake venom treatment, respectively. Overall knowledge predictors were ≥10 y working experience (odd ratio [OR] 1.72 [95% confidence interval {CI} 1.07 to 2.76]), urban hospital setting (OR 0.58 [95% CI 0.35 to 0.96]), surgery department (OR 0.44 [95% CI 0.24 to 0.81]), northwest/north-central region (OR 2.36 [95% CI 1.46 to 3.82]) and previous experience in snakebite management (OR 2.55 [95% CI 1.49 to 4.36]). Conclusions Overall knowledge was low. Improvements in overall knowledge may require clinicians’ exposure to snakebite management and training of accident and emergency clinicians in the region.
Article
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Summary Background Timely access to emergency care can substantially reduce mortality. International benchmarks for access to emergency hospital care have been established to guide ambitions for universal health care by 2030. However, no Pan-African database of where hospitals are located exists; therefore, we aimed to complete a geocoded inventory of hospital services in Africa in relation to how populations might access these services in 2015, with focus on women of child bearing age. Methods We assembled a geocoded inventory of public hospitals across 48 countries and islands of sub-Saharan Africa, including Zanzibar, using data from various sources. We only included public hospitals with emergency services that were managed by governments at national or local levels and faith-based or non-governmental organisations. For hospital listings without geographical coordinates, we geocoded each facility using Microsoft Encarta (version 2009), Google Earth (version 7.3), Geonames, Fallingrain, OpenStreetMap, and other national digital gazetteers. We obtained estimates for total population and women of child bearing age (15–49 years) at a 1 km² spatial resolution from the WorldPop database for 2015. Additionally, we assembled road network data from Google Map Maker Project and OpenStreetMap using ArcMap (version 10.5). We then combined the road network and the population locations to form a travel impedance surface. Subsequently, we formulated a cost distance algorithm based on the location of public hospitals and the travel impedance surface in AccessMod (version 5) to compute the proportion of populations living within a combined walking and motorised travel time of 2 h to emergency hospital services. Findings We consulted 100 databases from 48 sub-Saharan countries and islands, including Zanzibar, and identified 4908 public hospitals. 2701 hospitals had either full or partial information about their geographical coordinates. We estimated that 287 282 013 (29·0%) people and 64 495 526 (28·2%) women of child bearing age are located more than 2-h travel time from the nearest hospital. Marked differences were observed within and between countries, ranging from less than 25% of the population within 2-h travel time of a public hospital in South Sudan to more than 90% in Nigeria, Kenya, Cape Verde, Swaziland, South Africa, Burundi, Comoros, São Tomé and Príncipe, and Zanzibar. Only 16 countries reached the international benchmark of more than 80% of their populations living within a 2-h travel time of the nearest hospital. Interpretation Physical access to emergency hospital care provided by the public sector in Africa remains poor and varies substantially within and between countries. Innovative targeting of emergency care services is necessary to reduce these inequities. This study provides the first spatial census of public hospital services in Africa.
Article
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The economic and man-made resources that sustain human wellbeing are not distributed evenly across the world, but are instead heavily concentrated in cities. Poor access to opportunities and services offered by urban centres (a function of distance, transport infrastructure, and the spatial distribution of cities) is a major barrier to improved livelihoods and overall development. Advancing accessibility worldwide underpins the equity agenda of 'leaving no one behind' established by the Sustainable Development Goals of the United Nations. This has renewed international efforts to accurately measure accessibility and generate a metric that can inform the design and implementation of development policies. The only previous attempt to reliably map accessibility worldwide, which was published nearly a decade ago, predated the baseline for the Sustainable Development Goals and excluded the recent expansion in infrastructure networks, particularly in lower-resource settings. In parallel, new data sources provided by Open Street Map and Google now capture transportation networks with unprecedented detail and precision. Here we develop and validate a map that quantifies travel time to cities for 2015 at a spatial resolution of approximately one by one kilometre by integrating ten global-scale surfaces that characterize factors affecting human movement rates and 13,840 high-density urban centres within an established geospatial-modelling framework. Our results highlight disparities in accessibility relative to wealth as 50.9% of individuals living in low-income settings (concentrated in sub-Saharan Africa) reside within an hour of a city compared to 90.7% of individuals in high-income settings. By further triangulating this map against socioeconomic datasets, we demonstrate how access to urban centres stratifies the economic, educational, and health status of humanity.
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Introduction: Sri Lanka has a population of 21 million and about 80,000 snakebites occur annually. However, there are limited data on health seeking behavior following bites. We investigated the effects of snakebite and envenoming on health seeking behavior in Sri Lanka. Methods: In a community-based island-wide survey conducted in Sri Lanka 44,136 households were sampled using a multistage cluster sampling method. An individual who reported experiencing a snakebite within the preceding 12 months was considered a case. An interviewer-administered questionnaire was used to obtain details of the bite and health seeking behavior among cases. Results: Among 165,665 individuals surveyed, there were 695 snakebite victims. 682 (98.1%) had sought health care after the bite; 381 (54.8%) sought allopathic treatment and 301 (43.3%) sought traditional treatment. 323 (46.5%) had evidence of probable envenoming, among them 227 (70.3%) sought allopathic treatment, 94 (29.1%) sought traditional treatment and 2 did not seek treatment. There was wide geographic variation in the proportion of seeking allopathic treatment from <20% in the Western province to > 90% in the Northern province. Multiple logistic regression analysis showed that seeking allopathic treatment was independently associated with being systemically envenomed (Odds Ratio = 1.99, 95% CI: 1.36-2.90, P < 0.001), distance to the healthcare facility (OR = 1.13 per kilometer, 95% CI: 1.09 to 1.17, P < 0.001), time duration from the bite (OR = 0.49 per day, 95% CI: 0.29-0.74, P = 0.002), and the local incidence of envenoming (OR = 1.31 for each 50 per 100,000, 95% CI: 1.19-1.46, P < 0.001) and snakebite (OR = 0.90 for each 50 per 100,000, 95% CI: 0.85-0.94, P < 0.001) in the relevant geographic area. Conclusions: In Sri Lanka, both allopathic and traditional treatments are sought following snakebite. The presence of probable envenoming was a major contribution to seeking allopathic treatment.
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Background: Monitoring levels and trends in premature mortality is crucial to understanding how societies can address prominent sources of early death. The Global Burden of Disease 2016 Study (GBD 2016) provides a comprehensive assessment of cause-specific mortality for 264 causes in 195 locations from 1980 to 2016. This assessment includes evaluation of the expected epidemiological transition with changes in development and where local patterns deviate from these trends. Methods: We estimated cause-specific deaths and years of life lost (YLLs) by age, sex, geography, and year. YLLs were calculated from the sum of each death multiplied by the standard life expectancy at each age. We used the GBD cause of death database composed of: vital registration (VR) data corrected for under-registration and garbage coding; national and subnational verbal autopsy (VA) studies corrected for garbage coding; and other sources including surveys and surveillance systems for specific causes such as maternal mortality. To facilitate assessment of quality, we reported on the fraction of deaths assigned to GBD Level 1 or Level 2 causes that cannot be underlying causes of death (major garbage codes) by location and year. Based on completeness, garbage coding, cause list detail, and time periods covered, we provided an overall data quality rating for each location with scores ranging from 0 stars (worst) to 5 stars (best). We used robust statistical methods including the Cause of Death Ensemble model (CODEm) to generate estimates for each location, year, age, and sex. We assessed observed and expected levels and trends of cause-specific deaths in relation to the Socio-demographic Index (SDI), a summary indicator derived from measures of average income per capita, educational attainment, and total fertility, with locations grouped into quintiles by SDI. Relative to GBD 2015, we expanded the GBD cause hierarchy by 18 causes of death for GBD 2016. Findings: The quality of available data varied by location. Data quality in 25 countries rated in the highest category (5 stars), while 48, 30, 21, and 44 countries were rated at each of the succeeding data quality levels. Vital registration or verbal autopsy data were not available in 27 countries, resulting in the assignment of a zero value for data quality. Deaths from non-communicable diseases (NCDs) represented 72·3% (95% uncertainty interval [UI] 71·2–73·2) of deaths in 2016 with 19·3% (18·5–20·4) of deaths in that year occurring from communicable, maternal, neonatal, and nutritional (CMNN) diseases and a further 8·43% (8·00–8·67) from injuries. Although age-standardised rates of death from NCDs decreased globally between 2006 and 2016, total numbers of these deaths increased; both numbers and age-standardised rates of death from CMNN causes decreased in the decade 2006–16—age-standardised rates of deaths from injuries decreased but total numbers varied little. In 2016, the three leading global causes of death in children under-5 were lower respiratory infections, neonatal preterm birth complications, and neonatal encephalopathy due to birth asphyxia and trauma, combined resulting in 1·80 million deaths (95% UI 1·59 million to 1·89 million). Between 1990 and 2016, a profound shift toward deaths at older ages occurred with a 178% (95% UI 176–181) increase in deaths in ages 90–94 years and a 210% (208–212) increase in deaths older than age 95 years. The ten leading causes by rates of age-standardised YLL significantly decreased from 2006 to 2016 (median annualised rate of change was a decrease of 2·89%); the median annualised rate of change for all other causes was lower (a decrease of 1·59%) during the same interval. Globally, the five leading causes of total YLLs in 2016 were cardiovascular diseases; diarrhoea, lower respiratory infections, and other common infectious diseases; neoplasms; neonatal disorders; and HIV/AIDS and tuberculosis. At a finer level of disaggregation within cause groupings, the ten leading causes of total YLLs in 2016 were ischaemic heart disease, cerebrovascular disease, lower respiratory infections, diarrhoeal diseases, road injuries, malaria, neonatal preterm birth complications, HIV/AIDS, chronic obstructive pulmonary disease, and neonatal encephalopathy due to birth asphyxia and trauma. Ischaemic heart disease was the leading cause of total YLLs in 113 countries for men and 97 countries for women. Comparisons of observed levels of YLLs by countries, relative to the level of YLLs expected on the basis of SDI alone, highlighted distinct regional patterns including the greater than expected level of YLLs from malaria and from HIV/AIDS across sub-Saharan Africa; diabetes mellitus, especially in Oceania; interpersonal violence, notably within Latin America and the Caribbean; and cardiomyopathy and myocarditis, particularly in eastern and central Europe. The level of YLLs from ischaemic heart disease was less than expected in 117 of 195 locations. Other leading causes of YLLs for which YLLs were notably lower than expected included neonatal preterm birth complications in many locations in both south Asia and southeast Asia, and cerebrovascular disease in western Europe. Interpretation: The past 37 years have featured declining rates of communicable, maternal, neonatal, and nutritional diseases across all quintiles of SDI, with faster than expected gains for many locations relative to their SDI. A global shift towards deaths at older ages suggests success in reducing many causes of early death. YLLs have increased globally for causes such as diabetes mellitus or some neoplasms, and in some locations for causes such as drug use disorders, and conflict and terrorism. Increasing levels of YLLs might reflect outcomes from conditions that required high levels of care but for which effective treatments remain elusive, potentially increasing costs to health systems.
Article
This corrects the article DOI: 10.1038/nrdp.2017.63.
Article
Snakebite envenoming is a neglected tropical disease that kills >100,000 people and maims >400,000 people every year. Impoverished populations living in the rural tropics are particularly vulnerable; snakebite envenoming perpetuates the cycle of poverty. Snake venoms are complex mixtures of proteins that exert a wide range of toxic actions. The high variability in snake venom composition is responsible for the various clinical manifestations in envenomings, ranging from local tissue damage to potentially life-threatening systemic effects. Intravenous administration of antivenom is the only specific treatment to counteract envenoming. Analgesics, ventilator support, fluid therapy, haemodialysis and antibiotic therapy are also used. Novel therapeutic alternatives based on recombinant antibody technologies and new toxin inhibitors are being explored. Confronting snakebite envenoming at a global level demands the implementation of an integrated intervention strategy involving the WHO, the research community, antivenom manufacturers, regulatory agencies, national and regional health authorities, professional health organizations, international funding agencies, advocacy groups and civil society institutions.