Impacts of short-term weather on communicable enteric infectious diseases in western Europe: A case study of the Republic of Ireland, 2009–2020

Martin Boudou, Jean O’Dwyer, Patricia Garvey, Coilin O'hAiseadha, Paul Hynds

The incidence of sporadic enteric infections at temperate latitudes, including much of western Europe, vary seasonally, and as such are forecasted to shift in response to global climate changes. Understanding the associations between weather patterns and infection incidence is crucial to focus future surveillance efforts and minimise disease transmission. Accordingly, the relationship between antecedent mean ambient temperature, cumulative rainfall and weekly de-seasonalised incidence rates of three communicable pathogens, Campylobacter, Cryptosporidium, and Shiga-toxigenic Escherichia coli (STEC), delineated by five distinct settlement type classifications across the Republic of Ireland were investigated. A two-phase modelling strategy was employed, initiated via seasonal decomposition and followed by Bayesian structural time-series (BSTS) modelling of infection incidence using 0–20-week distributed temperature and rainfall lags. Models indicate that STEC enteritis is the most “climate driven” infection studied (R2=0.577), followed by cryptosporidiosis (R2=0.355) and campylobacteriosis (R2=0.207). Associations between antecedent local weather variables and infection differed significantly with respect to settlement type: national-scale patterns of campylobacteriosis reflected a combination of i) urban incidence characterised by an association with short-term (0-4 weeks) antecedent temperature (suggesting shifting social behaviours e.g., food consumption), and ii) rural incidence driven by long-term temperatures (10-18 weeks) and short-term precipitation (1-2 weeks) (indicating bimodal transmission mechanisms). Conversely, STEC enteritis exhibited high levels of variance with respect to antecedent hydrometeorological variables across both urban commuter (R2=0.495) and rural commuter (R2=0.407) areas, settlement types often characterised by high concurrent reliance on private water supplies, domestic wastewater treatment systems, and livestock grazing across much of Western Europe. Study findings may be used to inform development of risk-based, pathogen-specific surveillance strategies based on observed and future weather conditions to mitigate the human health impacts of climate change across temperate high-income regions.