Use of geospatial analyses to address snakebite hotspots in mid-northern Brazil - A direction to health planning in shortfall biodiversity knowledge areas

Epidemiological models to estimate the burden of snakebite envenoming: A systematic review

BACKGROUND

Epidemiological modelling studies in snakebite envenoming research are evolving. Their techniques can be essential in filling the knowledge gap needed to attain the World Health Organization's (WHO) goal of halving the burden of snakebite envenoming by complementing the current data scarcity. Hence, there is a need for a systematic review to summarise epidemiological models used in estimating the burden of snakebite envenoming.

METHODS

We conducted a systematic review by searching PubMed, EMBASE, and Scopus to identify articles reporting epidemiological models in snakebite envenoming from database inception to 31st December 2023. A narrative synthesis was performed to summarise types of models, methodologies, input parameters, model outputs, and associating factors.

RESULTS

Thirty-nine modelling studies were included from 2426 retrieved articles, comprising statistical models (76.9%) and mathematical models (23.1%). Most of the studies were conducted in South Asia, (35.9%) and Latin America (35.9%), and only a few (5.1%) were a global burden estimation. The eligible studies constructed 42 epidemiological models, of which 33 were statistical models that included regression, (60.6%) geostatistical (21.2%), and time series, (18.2%) while 9 mathematical models comprised compartmental, (44.4%) agent-based, (22.2%) transmission dynamics, (11.1%) network, (11.1%) and a simple mathematical model (11.1%). The outputs of the models varied across the study objectives. Statistical models analysed the relationship between incidence, (83.3%) mortality, (33.3%) morbidity (16.7%) and prevalence (10.0%) and their associating factors (environmental, [80%] socio-demographic [33.3%] and therapeutic [10.0%]). Mathematical models estimated incidence, (100%) mortality (33.3%), and morbidity (22.2%). Five mathematical modelling studies considered associating factors, including environmental (60%) and socio-demographic factors (40%).

CONCLUSION

Mathematical and statistical models are crucial for estimating the burden of snakebite envenoming, offering insights into risk prediction and resource allocation. Current challenges include low-quality data and methodological heterogeneity. Modelling studies are needed, and their continued improvement is vital for meeting WHO goals. Future research should emphasise standardised methodologies, high-quality community data, and stakeholder engagement to create accurate, applicable models for prevention and resource optimization in high-burden regions, including Africa and Asia.

The challenge in detecting risk areas of snakebite when case rates are low: the case of Amazonian coral snakes

Identifying risk areas for envenomation by animals is relevant for public health, such as strategic distribution of antivenoms. Coral snakes are highly diverse in the Amazon, inhabit natural and human-modified environments, and the outcome of the cases tends to be serious and potentially lethal due to their neurotoxic venom. By integrating species' geographical records and environmental variables, we used species distribution modeling to predict the distribution of coral snake species in the Brazilian Amazonia. We analyzed the relationship between the predicted distribution of coral snake species, along with envenomation data in the region, to propose actions to reduce the number of cases and to provide tools for a better policy of public health. We conclude that the entire Amazon shows high environmental suitability for coral snakes, and such suitability explains little about the incidence of cases. This is probably due to the low human density in the Amazon and to coral snake traits such as secretive habits and non-agressive behavior. Differently from other venomous snakes, the scenario regarding coral snakebites precludes the detection of prominent geographical areas of concern and demands a broad and equitable availability of health centers throughout Amazonia and along other areas of occurrence of the genus Micrurus.

Snakebites in Northeastern Brazil: accessing clinical-epidemiological profile as a strategy to deal with Neglected Tropical Diseases

BACKGROUND

Brazil ranks first in the number of snakebites in South America. A detailed analysis of these cases is required to improve the public health planning. In this study, we retrospectively examined the clinical and epidemiological profiles of snakebites in Maranhão between January 2009 and December 2019.

METHODS

Data were obtained from the compulsory notification forms provided by the Health Department of Maranhão.

RESULTS

A total of 17,658 cases were recorded during the study period. Most of the bites were from snakes belonging to the genus Bothrops. Medical care was mostly within three hours after the bite. Most cases were classified as mild and most victims recovered; however, 139 deaths were recorded. Most bites occurred among people aged 20-39 years, mainly among rural workers. The most frequent local clinical manifestations were pain, edema, and ecchymosis. The most common systemic clinical manifestations include neuroparalysis, vagal syndrome, and myolysis. Most snakebites occurred between January and March. The municipalities with the highest number of notifications were Buriticupu (936 cases), Arame (705 cases), and Grajaú (627 cases).

CONCLUSIONS

The clinical profile of snakebites in Maranhão is similar to that observed in other states of Northeast Brazil. However, we found that some systemic manifestations are not compatible with the etiology of snakebites, which leads us to believe that the problem could be the lack of knowledge of the health professionals at the site of envenomation, who may not be ready for attendance, and an important lack of health centers with snake antivenom to treat snakebites.

Who are the most affected by Bothrops snakebite envenoming in Brazil? A Clinical-epidemiological profile study among the regions of the country

Snakebite envenoming represents an important Neglected Tropical Disease (NTD) that mainly affects tropical and subtropical developing countries according to the World Health Organization (WHO). As a priority issue in the tropics, it is estimated that accidental encounter between snakes and humans is the leading cause of morbidity and mortality among all NTDs in the world. In Brazil, an extremely diverse country with continental dimensions, snakebite envenoming is the second leading cause of reported human envenoming. Treating the disease has been an unprecedented challenge for Brazilian Health Systems for decades. Despite access to Antivenom therapy and distributing it free of charge across the country, Brazil faces numerous issues regarding the notification process and accurate treatment targeting for at-risk populations. Thus, this study aimed to identify the temporal epidemiological dynamics of accidents caused by Bothrops snakes in Brazil, the country's major group of venomous snakes, based on secondary information from the online database provided by The Brazilian Notifiable Diseases Information System (SINAN). For this purpose, reported Bothrops snakebites between 2012 and 2021 were counted, then the data were analyzed. We looked at the frequency, occurrence, mortality rates, case fatality rate (CFR), age and gender distribution, and the time lapse between the incident and the initiation of Antivenom therapy. The data were also organized considering regional variations of the country. Throughout the studied period, a total of 202,604 cases of envenoming caused by Bothrops spp. were notified, resulting in 766 fatalities. These accidents were found to occur in variable proportions across different regions in Brazil, with notable concentrations observed in the North, Northeast, and Southeast regions. The epidemiological profile of patients varied greatly between the regions, revealing that snake envenoming is much more a social, economic, and ecological problem than a medical one. In conclusion, our study provides an overview of the clinical and epidemiological profile of envenoming by Bothrops snakes in Brazil. Notably, this is the first study to present such information in a country as vast and diverse as Brazil, encompassing a comparative analysis of its regions using SINAN data, that proves to be a very useful national tool to improve the control and management of envenoming.

Environmental drivers of tropical forest snake phenology: Insights from citizen science

Museum specimens and citizen science initiatives are valuable sources of information on how anthropogenic activities affect biodiversity and how species respond to rapid global change. Although tropical regions harbor most of the planet's biodiversity, investigations on species' phenological changes are heavily biased toward temperate regions. Such unevenness in phenological research is also taxonomically biased, with reptiles being the least studied group among tetrapod species regarding animal phenology. Herein, we used long-term time-series data to investigate environmentally driven changes in the activity pattern of tropical forest snakes. We gathered natural history collection and citizen science data for 25 snake species (five venomous and 20 non-venomous) from an Atlantic Forest region in southeastern Brazil. Using circular mixed-effects models, we investigate whether snake activity patterns followed the variation in environmental variables over a decade. Our results show that the activity pattern of Atlantic Forest snakes was seasonal and largely driven by average temperature and relative humidity. Since snakes are ectothermic animals, they are particularly sensitive to temperature variations, especially at small scales. Moreover, relative humidity can affect snake's seasonal activities through physiological constraints and/or prey availability. Most specimens were registered during the rainy season, with highly venomous snakes (lanceheads and coral snakes) emerging as the most abundant taxa. We highlight the importance of citizen science and natural history collections in better understanding biodiversity. Furthermore, our data obtained from local collectors underscore the need for environmental education programs and collaboration between researchers and local decision-makers to raise awareness and reduce conflicts between people and snakes in the region.

Identification of Risk Areas for Gloydius Snakebites in South Korea

Snakebites can pose a significant threat to human health as the destruction of natural habitats and increased human intrusion into ecosystems result in more frequent encounters with snakes. Mitigation measures for snakebites are particularly crucial for hiking trails where transportation of snakebite victims to medical facilities is challenging due to limited emergency resources and difficult access. This study employed a random forest-based species distribution model approach to investigate the potential habitats of Gloydius spp., specifically Gloydius saxatilis, Gloydius brevicaudus, and Gloydius ussuriensis, in South Korea and to assess the snakebite risk in national parks. Potential habitats of Gloydius spp. were identified and visualized by overlaying binary maps derived from species distribution models (SDMs) of each Gloydius spp. that corresponded to high-risk snakebite areas. In addition, hiking trails with high snakebite risk in the national parks were identified after demonstrating the statistical correlation between the potential habitat distribution of Gloydius spp. and the actual snakebite incidents in major regions of South Korea. The primary environmental variables determining Gloydius spp. habitat were the topographic position index, slope, and the annual average of the maximum and minimum temperatures. The potential habitat of G. saxatilis generally appeared in high-altitude mountainous areas, mostly in the eastern part of the study area. Favorable habitats for G. brevicaudus and G. ussuriensis were predominantly located in mountainous areas throughout the study area, with the exception of some high-altitude mountainous terrain in the east. The number of snakebite incidents per 10,000 people was significantly correlated with the area ratio of Gloydius spp. potential habitat (Spearman's rho = 0.638, p < 0.01). The proportion of snakebite risk areas among national parks in South Korea ranged from 18% to 57%. This study can support practical solutions to prevent injuries and fatalities among hikers due to snakebites by identifying areas with a high risk of snakebite accidents at the hiking-trail level.

Identifying high snakebite risk area under climate change for community education and antivenom distribution

Snakebite is one of the largest risks from wildlife, however 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. Here we used habitat suitability modeling for 10 medically important venomous snakes to identify high snakebite risk area under climate change in Iran. We identified areas with high snakebite risk in Iran and showed that snakebite risk will increase in some parts of the country. Our results also revealed that 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.

Bibliometric Analysis of Literature in Snake Venom-Related Research Worldwide (1933-2022)

Snake envenomation is a severe economic and health concern affecting countries worldwide. Snake venom carries a wide variety of small peptides and proteins with various immunological and pharmacological properties. A few key research areas related to snake venom, including its applications in treating cancer and eradicating antibiotic-resistant bacteria, have been gaining significant attention in recent years. The goal of the current study was to analyze the global profile of literature in snake venom research. This study presents a bibliometric review of snake venom-related research documents indexed in the Scopus database between 1933 and 2022. The overall number of documents published on a global scale was 2999, with an average annual production of 34 documents. Brazil produced the highest number of documents (n = 729), followed by the United States (n = 548), Australia (n = 240), and Costa Rica (n = 235). Since 1963, the number of publications has been steadily increasing globally. At a worldwide level, antivenom, proteomics, and transcriptomics are growing hot issues for research in this field. The current research provides a unique overview of snake venom research at global level from 1933 through 2022, and it may be beneficial in guiding future research.