The Association Between Heat Waves and Other Meteorological Parameters and Snakebites: Israel National Study.

BACKGROUND: Published annual estimates report a global burden of 2.5 million snakebite cases and >100,000 deaths. In Israel, envenomations are the third most frequent cause of poisonings that are of moderate to major clinical severity. Most studies focus on the clinical descriptions of snakebites in tropical climates, and we sought to investigate the association between snakebite frequency and meteorological parameters.

OBJECTIVE: We sought to investigate the seasonality of snakebites and evaluate the association between increasingly common heat waves and other meteorological parameters and snakebite frequency in a semiarid nontropical climate.

METHODS: We obtained data for all medical evacuations (2008-2015) because of snakebites in Israel. Climate data included daily 24-hour average temperature (°C) and relative humidity (%). We used a time-stratified case crossover method, in which a conditional logistic regression was applied to estimate the association, and we also stratified our analysis by season and by region.

RESULTS: We identified 1234 snakebite cases over 8 years, of which most (74.2%) occurred in hot seasons and between 6 pm and 9 pm. The risk of snakebite was positively associated with temperature >23°C (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.01-1.53) and inversely with humidity >40% (OR 0.74, 95% CI 0.57-0.97). We also found an association with heat waves both in cold (OR 1.62, 95% CI 1.01-2.60) and hot seasons (OR 1.50, 95% CI 1.18-1.92).

CONCLUSIONS: In a semiarid nontropical climate, we observed an association between an increase in the number of snakebite cases and higher temperatures and lower humidity. Moreover, heat waves increased the frequency of snakebites in both cold and hot seasons.