Special Assessment of Dengue and Percipitation in the ASEAN Region

ASEAN Member States have tropical climates that favor Aedes aegypti breeding, yet the timing of rainfall-related changes in dengue incidence may differ substantially among countries. This exploratory study assessed country-specific associations between precipitation and reported dengue cases, including temporal lags. National dengue surveillance data were paired with NASA POWER precipitation estimates and aggregated to each country's reporting frequency. Pearson correlation coefficients were calculated for 11 ASEAN Member States across lags of 0-6 months for monthly series and 0-12 weeks for weekly series. Lag patterns were heterogeneous. Viet Nam showed the strongest monthly shortlag association, peaking at 1 month (r = 0.72). Among weekly series, Lao PDR and Thailand peaked at 5 weeks (r = 0.68 and 0.47, respectively), whereas Myanmar peaked at 2-3 weeks (r = 0.53). Timor-Leste remained positively correlated across all evaluated lags (r = 0.48-0.68). Brunei Darussalam, Cambodia, and Indonesia showed weaker associations; Malaysia showed little consistent positive association; and Singapore showed negative correlations throughout the evaluated lag window. Estimates for the Philippines were unstable because of its short observation period and the small number of paired observations at longer lags. No single precipitation-dengue lag pattern applied across the region. Because inferential testing was not performed, the results should be interpreted as hypothesis-generating rather than causal. These findings support countryspecific, multivariable early-warning models using longer time series, subnational exposure data, harmonized temporal scales, and methods that address seasonality, autocorrelation, nonlinear effects, and uncertainty.