Meteorological predictors of dengue hemorrhagic fever incidence in Cilacap Regency, Indonesia: A time series analysis
Abstract
To analyze the nonlinear relationship between meteorological predictors and dengue hemorrhagic fever, and to quantify the meteorologically attributable fraction of dengue hemorrhagic fever (DHF) during 2021-2025 in Cilacap Regency. This ecological time series design used sequential three-stage analytical tools, including a cross-correlation function (CCF) analysis applied to identify lag structures, Granger causality within a vector autoregression (VAR) framework used to confirm directional temporal precedence, and a quasi-Poisson Distributed Lag Nonlinear Model (DLNM) with natural cubic spline crossbases over a 28-day lag window used to estimate the exposure-response relationship. Autoregressive terms alongside long-term trends and seasonal splines were incorporated to account for autocorrelation and potential confounding. Granger causality testing confirmed unidirectional of DHF relationships across all four predictors, including mean temperature, rainfall, relative humidity, and wind speed (all P <0.05). Among these, daily rainfall emerged as the dominant predictor [relative risk ( RR ) 4.23; 95% CI 2.10-8.52)], a peak CCF lag of 7 days, and an attributable fraction of 27.58%. The mean temperature displayed a J-shaped exposure-response curve, with a protective nadir at 26.5°C, and markedly elevated risk above 28 °C [ RR 2.13; 95% CI 1.43-3.19; Attributable Fraction (AF) = 6.22%]. Relative humidity (AF= -14.40%) and wind speed (AF= -3.37%) demonstrated complex nonlinear patterns contributing net protective attributable fractions. Overall, the model explained 52.26% of the null deviance (QAIC= 3 984.23). Rainfall and temperature were the meteorological predictors most strongly associated with DHF incidence in Cilacap Regency. This finding provides evidence for actionable vector control program and early warning system of DHF to consider the utilization of meteorological predictor to prevent DHF outbreak in Cilacap.