The impacts of global and local climates on dengue fever in Lao PDR and Cambodia.

Abstract

Background: Climate change and climate variability are increasingly recognized as one of factors influencing emergence or re-emergence of vector-borne diseases such as dengue fever. For the past years, the increment of dengue has been observed and studies showed much evidence of strong correlations between climate variables and dengue cases. There is the potential increase in the latitudinal and altitudinal distribution of vector mosquitoes and dengue under global warming. Aims: This study was conducted to explore the associations between climate variables and dengue fever in Lao PDR and Cambodia. Methods: Dengue case data was obtained from three regions (North, Central, and South) of Lao PDR (2005-2010) and two cities (Phnom Penh and Siem Reap) of Cambodia (2006-2011). Time series analysis was performed to assess the associations with monthly climate variability, fitting global climate Southern Oscillation Index (SOI) and Dipole Mode Index (DMI)) and local weather variables (rainfall and maximum temperature) into generalized linear quasi-Poisson models. Result: The seasonality of dengue cases appeared to be mostly concomitant with rainy season (April to September) in both countries. Rainfall was positively associated with the number of dengue cases throughout the year in all locations whereas SOI showed a negative association. The effects of maximum temperature and DMI, on the other hand, varied depending on season and location, and the consistent pattern was hardly defined. Conclusion: In both countries, the number of dengue cases was positively and negatively associated with rainfall and SOI, respectively. The effects of maximum temperature and DMI were highly variable. Understanding the association between rainfall and SOI might assist further clarification of the impact of climate change on dengue fever.