The impact of climate on the prevalence of respiratory tract infections in early childhood in Lahore, Pakistan.

BACKGROUND: Respiratory tract infections are a major health problem in developing countries. The aim of this study was to analyse the impact of the climate on the prevalence of upper respiratory tract infection (URTI) and lower respiratory tract infection (LRTI) in four socioeconomically different groups in a developing country. METHODS: A prospective cohort study was conducted among children in four socioeconomically different groups in Lahore, Pakistan. Monthly observations were made on 1476 infants born during 1984-1987 and followed for 24 months. Prevalence of URTI and LRTI was analysed according to age, area of living, family size, time of birth, the season of the year and climate variables such as rain, temperature and humidity. RESULTS: Low monthly average minimum day temperature was associated with high prevalence of URTI and LRTI. For LRTI the impact of temperature was larger for boys, children living in larger families and children living in the poorer areas. This pattern was not seen for URTI. A peak in prevalence for LRTI was shown at 5-6 months of age for LRTI and at 10-12 months of age for URTI. CONCLUSIONS: Temperature is related to prevalence of URTI and LRTI in a developing society. The effect of temperature on health varies between different subgroups. These effects should be considered in planning health actions to prevent respiratory tract infections.