Sara Babo Martins

Background: Worldwide, it is estimated that snakes bite 4.5–5.4 million people annually, 2.7 million of which are envenomed, and 81,000–138,000 die. The World Health Organization reported these estimates and recognized the scarcity of large-scale, community-based, epidemiological data. In this context, we developed the “Snake-Byte” project that aims at (i) quantifying and mapping the impact of snakebite on human and animal health, and on livelihoods, (ii) developing predictive models for medical, ecological and economic indicators, and (iii) analyzing geographic accessibility to healthcare. This paper exclusively describes the methodology we developed to collect large-scale primary data on snakebite in humans and animals in two hyper-endemic countries, Cameroon and Nepal. Methodology/Principal findings: We compared available methods on snakebite epidemiology and on multi-cluster survey development. Then, in line with those findings, we developed an original study methodology based on a multi-cluster random survey, enhanced by geospatial, One Health, and health economics components. Using a minimum hypothesized snakebite national incidence of 100/100,000/year and optimizing design effect, confidence level, and non-response margin, we calculated a sample of 61,000 people per country. This represented 11,700 households in Cameroon and 13,800 in Nepal. The random selection with probability proportional to size generated 250 clusters from all Cameroonian regions and all Nepalese Terai districts. Our household selection methodology combined spatial randomization and selection via high-resolution satellite images. After ethical approval in Switerland (CCER), Nepal (BPKIHS), and Cameroon (CNERSH), and informed written consent, our e-questionnaires included geolocated baseline demographic and socio-economic characteristics, snakebite clinical features and outcomes, healthcare expenditure, animal ownership, animal outcomes, snake identification, and service accessibility. Conclusions/Significance: This novel transdisciplinary survey methodology was subsequently used to collect countrywide snakebite envenoming data in Nepal and Cameroon. District-level incidence data should help health authorities to channel antivenom and healthcare allocation. This methodology, or parts thereof, could be easily adapted to other countries and to other Neglected Tropical Diseases.

Background: Each year, two million people worldwide suffer snakebite envenoming (SBE), resulting in up to 138,000 deaths. The World Health Organization has added SBE to the list of Neglected Tropical Diseases, calling for stronger epidemiological evidence in highly endemic countries such as Nepal. Methods: We conducted a cross-sectional survey in 249 randomly selected clusters across Nepal’s Terai region, including 13,879 geospatially selected households. We analysed snakebite incidence rates and outcomes in humans and domestic animals. Findings :Among 63,454 human participants, 166 suffered snakebites over the previous 12 months; 48·8% were envenomed and 7·8% died. This corresponded to annual incidence rates of 262 snakebites [95% CI 225–305] , 127 envenomings [102–158], and 20 [12–35] deaths per 100,000 individuals, extrapolating into 37,661 yearly victims [32,362–43,836] and 2,949 deaths [1,728–5,053] in the Terai. Victim median age was 30 years (IQR 20–45) and 60% were female. Children younger than 15 years (n=6; 46%) and females (n=10; 77%) were over-represented among the 13 deceased. Incidence was higher in Eastern, and mortality in Central regions. Of 184,999 animals, owners reported 144 snakebites, with annual incidence rates of 42-202 and mortality of 79-100 per 100,000 varying by animal type. Spatial and seasonal incidence were similar in humans and animals. Conclusion: This first One Health study on snakebite across Nepal’s Terai shows high incidence and mortality rates in humans and animals. These results call for strengthening of preventive measures and better access to life-saving treatments. Funding: Swiss National Science Foundation project 315130_176271 (SNAKE-BYTE) Declaration of Interest: None to declare. Ethical Approval: The study was approved by the Nepal Health Research Council (NHRC Reg. 585/2018), and Commission Cantonale d’Ethique de la Recherche Scientifique in Geneva, Switzerland (CCER/SwissEthics Registry No. 2018-01331).

Snakebite envenoming causes up to 138,000 deaths and 400,000 permanently disabled victims worldwide every year. Flooding is one of the many factors that seems to influence the incidence of snakebite. The catastrophic floods from late 2018 in Kerala (India) were widely broadcast and are an example of how flooding events are related to the increased incidence of snakebite. This relationship has been mentioned regularly in scientific and grey literature, but usually quite scarcely in comparison to other topics linked to snakebite. Additionally, web media, mobile communications, and social media have started playing an important role not only in providing access to information on flooding-related snakebite events, but also in snakebite prevention at a larger scale. In order to better understand to what extent the relationship between snakebite incidence and flooding is reported and quantified and appraise the importance of mobile communications and social media in snakebite prevention and management, we performed multiple searches in generic (Google) and specialized (PubMed, Web of Science, Google Scholar) databases. We retrieved 68 scientific articles and 5 reports ranging from 1892 to 2018 mentioning or analyzing flooding and the increased incidence of snakebite. Additionally, we found 68 web media reports linking flooding and snakebite. This review indicates that the increase of snakebite incidence due to flooding has been repeatedly observed all over the world. This phenomenon could be exacerbated because of climate change, which is expected to increase the overall magnitude and frequency of flooding. However, it could also be mitigated by the role the Internet, mobile communications, and social media could play in snakebite prevention and human and animal rescue strategies during flooding.

Since 2013 in Emilia-Romagna, Italy, surveillance information generated in the public health and in the animal health sectors has been shared and used to guide public health interventions to mitigate the risk of West Nile virus (WNV) transmission via blood transfusion. The objective of the current study was to identify and estimate the costs and benefits associated with this One Health surveillance approach, and to compare it to an approach that does not integrate animal health information in blood donations safety policy (uni-sectoral scenario). Costs of human, animal, and entomological surveillance, sharing of information, and triggered interventions were estimated. Benefits were quantified as the averted costs of potential human cases of WNV neuroinvasive disease associated to infected blood transfusion. In the 2009–2015 period, the One Health approach was estimated to represent a cost saving of €160,921 compared to the uni-sectoral scenario. Blood donation screening was the main cost for both scenarios. The One Health approach further allowed savings of €1.21 million in terms of avoided tests on blood units. Benefits of the One Health approach due to short-term costs of hospitalization and compensation for transfusion-associated disease potentially avoided, were estimated to range from €0 to €2.98 million according to the probability of developing WNV neuroinvasive disease after receiving an infected blood transfusion.