Snake-byte: first national epidemiological study on snakebite shows high annual incidences in Nepal and Cameroon

Introduction: Snakebite envenoming affects 4.5-5.4 million people and kills 81,000-138,000 victims yearly according to the World Health Orga- nization (WHO), but estimates are extrapolations, and community-based country-wide studies are very scarce. Aim: To measure the impact of snakebite on human and animal health (incidence, mortality, disability) and livelihoods in Cameroon and Nepal. Methods: This epidemiological study is part of the SNAKE-BYTE project that aims at understanding the impact of snakebite in Cameroon and Nepal through one-health, health economy, and epidemiology using digital epidemiology and geo-health tools (Kobo-collect®, Stata® qGIS®, Guru-Maps®, AccesMod®). Based on minimal expected snakebite inci- dence of 100/100,000/year, 0.05% confidence limit, design effect of 2.0, 99% confidence level, 15% non-response margin, sample size was 61,000 people per country, i.e. 11,700 households in Cameroon and 13,800 in Nepal (respectively 5.2 and 4.4 persons per household). Households were preselected from satellite images, among 500 (2x250) randomly prese- lected administrative areas, where six mobile survey teams conducted the e-questionnaires. After ethical approval by Cameroonian, Nepalese, and Swiss authorities, surveys started in November 2018. Results: Interim data analysis on 5045 households in Cameroon and 10,163 in Nepal, showed respectively 120 victims per 29,537 persons- year and 141 victims per 46,888 persons-year. National snakebite inci- dence rates per 100,000 persons-year translate to 406.3 (95%CI: 338.3, 484.0) or 65,008 victims in rural Cameroon (population 16 million), and 300.7 (95%CI: 254.1, 353.5) or 39,993 victims in Nepal's Terai lowlands (population 13.3 million). Victims were young adults (median 30/31y), often farmers, predominantly males in Cameroon (54.5%) and females in Nepal (66.4%), and 22.5% were children