The role of tropical cyclones in accelerating dengue transmission: insights from field experiments and dynamical modelling.

INTRODUCTION

To quantify the impact of tropical cyclones on dengue transmission dynamics and related disease burden by integrating field entomology with dynamic modelling in Guangzhou, China.

METHODS

Guangzhou was selected as the study site considering that it is China's most dengue-endemic coastal megacity with frequent tropical cyclones and the country's largest recorded dengue outbreak in 2014. Mark-release-recapture experiments with laboratory simulations were performed in 2024 to assess the flight distance, reproduction and survival of Aedes albopictus under cyclone and baseline conditions to estimate human-mosquito contact rates. These data informed a dynamic susceptible-incubation-infected-recovered model simulating the 2014 dengue epidemic during Typhoons Rammasun and Kalmaegi. We estimated excess cases and economic losses against counterfactual baselines and projected the impact of enhanced vector control.

RESULTS

During cyclones, Aedes albopictus maximum flight distance increased by 63.0% and human-mosquito contact rate by 30.1%. Estimated R0 increased from 1.10 (baseline) to 1.43 (Rammasun) and 1.29 (Kalmaegi). The estimated excess burden reached 217 excess cases (US$76 400) for Rammasun and 5131 cases (US$1.93 million) for Kalmaegi. Enhanced vector control during Kalmaegi was projected to avert 59 360 additional cases (US$20.91 million).

CONCLUSIONS

Tropical cyclones amplify dengue transmission by expanding mosquito dispersal and intensifying human-vector contact. Early vector control, guided by warnings, substantially reduces cases and costs.