Rainfall, household crowding, and acute respiratory infections in the tropics

Abstract

SUMMARYAcute respiratory infections (ARI) are the leading cause of death worldwide in children aged <5 years, and understanding contributing factors to their seasonality is important for targeting and implementing prevention strategies. In tropical climates, ARI typically peak during the pre-rainy and rainy seasons. One hypothesis is that rainfall leads to more time spent indoors, thus increasing exposure to other people and in turn increasing the risk of ARI. A case-crossover study design in 718 Bangladeshi children aged <5 years was used to evaluate this hypothesis. During a 3-month period with variable rainfall, rainfall was associated with ARI [odds ratio (OR) 2·97, 95% confidence interval (CI) 1·87-4·70]; some evidence of an increased strength of association as household crowding increased was found (≥3 people/room, OR 3·31, 95% CI 2·03-5·38), but there was a lack of association in some of the most crowded households (≥5 to <6 people/room, OR 1·55, 95% CI 0·54-4·47). These findings suggest that rainfall may be increasing exposure to crowded conditions, thus leading to an increased risk of ARI, but that additional factors not captured by this analysis may also play a role.

The association between the incidence of mumps and meteorological parameters in Taiwan

“…44 Thereby, each subject's exposure prior to a case-defining event is compared with his or her own exposure during a control period when he/she had not yet been diagnosed as a case. A case day was the day on which the first symptom of mumps presented, 45,46 and the case period was 0-14 d prior to that day. The control day was selected 2 to 4 weeks before the case date (14-28 d prior to the case day).…”

Epidemiology and seasonality of respiratory viral infections in hospitalized children in Kuala Lumpur, Malaysia: a retrospective study of 27 years

“…Malaysia experiences brief, intense showers of rainfall, as well as prolonged episodes of light rainfall. Therefore, the number of rain days may have a greater influence than the absolute amount of rainfall on behaviours such as children staying indoors, thus increasing close contact and indoor transmission of respiratory viruses [33]. …”

Incidence of influenza-associated hospitalization in rural communities in western and northern India, 2010–2012: A multi-site population-based study

“…These factors have been implicated in the transmission dynamics of respiratory infections and more specifically for influenza. 19,20 Modelling has shown the existence of two types of environmental conditions which Incidence of influenza-associated hospitalization explain the different seasonality of influenza globally e cold-dry as in temperate climates like United States and Europe; and humiderainy as in tropical climates of south-east Asia. 21 Antigenic and genetic analysis of the viruses circulating at Vadu and Ballabgarh suggest that the viruses circulating at both sites were similar making it unlikely that inherent differences in circulating viruses were responsible for differences in clinical features and hospitalization rates between the two sites.…”