Work

Contrasting pandemic era trajectories of dengue; chikungunya; and hand, foot, and mouth disease in Thailand using national surveillance findings, 2016–2025

Year: 2026

Type: article

Abstract: Objectives: To compare the pandemic era trajectories of dengue; chikungunya; and hand, foot, and mouth disease (HFMD) in Thailand. Methods: We conducted a national ecological interrupted time series analysis using weekly surveillance data from all 77 Thai provinces from 2016 to 2025. Segmented quasi-Poisson regression with Fourier terms for annual seasonality estimated the level and slope changes at a calendar-based 2020 break point; sensitivity analyses used later break points. Results: The analysis included 40579 province-week observations including 790263 dengue, 32265 chikungunya, and 713822 HFMD cases. The estimated level incidence rate ratios at week 1 of the 2020 break point were 0.39 for dengue (95% confidence interval [CI] 0.32-0.48), 0.54 for chikungunya (95% CI 0.41-0.71), and 0.51 for HFMD (95% CI 0.38-0.69). Dengue rebounded above pre-pandemic levels by 2023, chikungunya declined after the 2018-2020 outbreak, and HFMD's mean annual incidence in 2023-2025 exceeded the pre-pandemic baseline by approximately 26%. Conclusions: These contrasting trajectories support the need for comparative multi-disease surveillance. Ecological designs cannot separate the contribution of transmission ecology from epidemic history or other time-varying factors.

Source: IJID Regions

DOI: 10.1016/j.ijregi.2026.101037

Authors: Wannarat Pongpirul, Mohamed Mustaf Ahmed, Krit Pongpirul