Emerging trends of malaria-dengue geographical coupling in the Southeast Asia region.

BACKGROUND & OBJECTIVES Malaria and dengue fever are the most common mosquito-borne diseases in the Southeast Asia region (SEAR). We analysed a temporal record of annual cases of malaria and dengue fever from 1985-2009 in SEAR. METHODS Data of dengue and malaria cases were obtained from WHO website for the period from 1985-2009. El-Nino Southern Oscillation (ENSO) fluctuation data were obtained from NOAA Climate Prediction Centre, Maryland. The wavelet analysis was conducted to analyse the data. RESULTS RESULTS showed that multiyear cycles of malaria outbreaks appeared in 1986 and 1996, concomitant with the timing of dengue cases at one year lag. The dynamics of both cases pronounce a regime shift in the 1999, when the coupling between dengue and ENSO is also stronger. The statistical significance of this coupling is evident from wavelet band-averaged cross power in 2-4 yr scale (95% confidence level). INTERPRETATION & CONCLUSION The present analysis suggests that the dengue incidence patterns in SEAR are periodic. There is not much evidence of malaria and ENSO having periodic association in the region; however, dengue fever and ENSO shows statistical significant cross-coherence in the 2-4 yr wavelet band and the results are statistically significant in the last decade. This study also provides statistical evidence of geographical clustering which quantitatively demonstrate the cross-country and cross-epidemic situations that exist across SEAR.