Latitudinal Variation in Childhood Diarrhoea is associated with Local Rainfall and Population Density

Abstract

Background/Aim: Scientists have long predicted the impacts of climate-related infectious disease emergence, and yet the extent to which local socioeconomic and demographic drivers can mask the influence of weather variation and environmental settings on child health is widely debated. Models that couple weather and environmental conditions with demographic factors offer a potentially improved approach for estimating shifts in disease distribution and risk under climate change. Methods: With a focus on childhood diarrhoea caused by the parasite Cryptosporidium spp., – an infection easily controlled by public health interventions but also strongly linked to environmental conditions through waterborne spread, we systematically review and empirically model the effects of local weather and flooding history on cryptosporidiosis, after controlling for seasonality, publication bias, access to improved sanitation, health resources and population density at a global scale. Results: We examined 1588 papers on childhood cryptosporidiosis and identified 36 studies representing a range of geographic locations and climatic, environmental and socio-economic conditions. Generalized linear mixed effects models for equatorial, sub-tropical and temperate climates found local rainfall and population density were the most important determinants of childhood cryptosporidiosis across all regions. In lower latitudes, local rainfall and population density were significant and positively associated with childhood cryptosporidiosis. In temperate latitudes there was a significant negative association of disease with rainfall and a positive association with population density. Conclusions: This global empirical analysis indicates that climate and demographic change can affect childhood cryptosporidiosis, with differential patterns between low and high latitude regions. These findings underscore the need to consider locality specific environmental and demographic factors when assessing disease distributional shifts and risks due to climate change. These results may have implications for developing environment-focused public health policies to manage health risks of climate change for future generations.