Impacts of temperature, diurnal temperature range, heat index and heat wave on diarrhoeal diseases in Dhaka, Bangladesh in the context of climate change: a time-series analysis

Although several studies investigated the impact of climate variability on human health, a comprehensive understanding of the relationship between climate variability and waterborne infectious diseases is lacking. This thesis examines the relationship of key climate parameters likely to be impacted by climate change (temperature, diurnal temperature range (DTR), heat index (HI) and heat wave) with hospitalisation for all-cause diarrhoeal diseases in Dhaka, Bangladesh, using time-series regression analyses. A 1°C higher daily mean temperature was associated with a 3.4% increase in all-cause diarrhoea hospitalisations in all ages. A 1°C higher DTR, and low (94.3°F), high (>98.4°F), very high (>100.7°F) and extremely high HI (>105°F) were associated with 0.8%, 8%, 7%, 7% and 9% increase in diarrhoea hospitalisation, respectively. Compared to a non-heat wave day, diarrhoea admissions increased by 6.7%, 8.3%, 5.6% and 6.2% in all ages and by 13.9%, 24.2%, 15% and 17% in children aged under 5 years on a TAV95, TAV99, HI95 and HI99 heat wave day (defined as the day where the average temperature or heat index exceeded the 95th and 99th percentile), respectively. Regional climate projections suggest an increase of 1.5 – 2°C in daily mean temperature by the 2050s, which would be predicted to result in an increase of 5.1 - 6.8% in daily diarrhoea hospitalisation in Dhaka. Ambient temperature, DTR, HI or heat wave are associated with diarrhoea hospitalisation in Dhaka. Given the high prevalence of diarrhoeal diseases, high population density, and sub-optimal infrastructure, even a small increase in risk of diarrhoea hospitalisations could overwhelm healthcare services. This underscores the importance of preparing Dhaka for prevention and management of diarrhoeal diseases in anticipation of climate change