An ecologic study on the presumed impacts of climate change and seasonal patterns on acute respiratory infection and health service utilization in Nueva Ecija from 1999 to 2008.

OBJECTIVE: Only recently has the effects of weather on disease prevalence been brought to attention.To better understand this relationship, the study identified the probable impacts that climate change and seasonal patterns may have to the prevalence of both acute respiratory infections (ARI) and health services utilization.

METHODS: This mixed-ecologic study explored the possible consequences that temperature, rainfall, humidity and wind had on ARI prevalence and rural health unit (RHU) consultations in the entire province of Nueva Ecija. Monthly data for ARI and consults were obtained through consultation logbooks from each RHU in the province, while climate data were provided by the Manila Observatory.These were then subjected to linear regression, cross correlation, and spatial analyses.

RESULTS: Although the study failed to prove or disprove the occurrence of climate change, the sequence graphs established seasonality of weather occurrence.In the analysis of seasonal patterns, relative humidity was found to be correlated with both ARI (Pearson's R=0.605, CI=95%), and consults prevalence (Pearson's R=0.584, CI=95%). Wind speed also affected ARI prevalence (R2=0.088, P value=0.045, CI=95%). Spatial analysis showed an unequal distribution of all variables across Nueva Ecija, with ARI and consultations being more prevalent in the eastern half of the province.

CONCLUSIONS: Due to the short study period, the study failed to prove the occurrence or non-occurrence of climate change.Thus, any correlations cannot be made in relation to such meteorological phenomena.however, several issues may be said about seasonal patterns. In Nueva Ecija, they occur from December to May for the dry months and from June to November for the rainy season, in varying degrees throughout the province.The occurrence of ARI prevalence and consults prevalence likewise follow cyclical fluctuations and differences in geographic distribution; they increase during humid conditions, when damp air is most likely to promote bacterial, fungal, and viral growth, and decrease during less humid months.Additionally, wind speed also increase ARI cases, possibly by spreading pathogens through the air. Although these weather-disease associations are confirmed by the study, causality and mechanisms behind them require more investigation.