Dengue Situation and Trends in Thailand, 2026

Abstract

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• Dengue fever is a vector borne disease caused by the dengue virus (DENV), which comprises four distinct serotypes: DENV-1, DENV-2, DENV-3, and DENV-4. Transmission occurs from person to person through infected mosquito vectors, primarily the Aedes aegypti. Epidemics typically peak during the rainy season, spanning from May to August. Currently, dengue can be prevented through vaccination.
• The majority of cases remain asymptomatic or present with mild symptoms. However, the infection can lead to complications and fatalities. Upon suspicion of infection, immediate medical consultation is imperative to ensure prompt diagnosis.
• The dengue situation in Thailand over the past five years (2021–2025) indicated morbidity rates ranging from 16.04 to 243.43 per 100,000 population. As of 24 June 2026, a total of 10,551 dengue cases had been reported, which was below the 5-year median. Fifteen deaths were reported, corresponding to a case fatality rate (CFR) of 0.14%. The highest disease burden was observed in the southern region of the country. Although the current trend indicates a decline in reported cases, dengue incidence is expected to increase during the rainy season. Therefore, continuous surveillance and preparedness measures remain essential.
• Recommendations for Dengue Fever Prevention and Control.The public is advised to implement the "3 Clean-ups to Prevent 3 Diseases" strategy, which entails maintaining clean households, disposing of solid waste, and securing water containers to eliminate vector breeding sites. Furthermore, individuals must closely monitor their symptoms. Those presenting with an acute high fever, or a fever that does not subside despite the administration of antipyretics, should seek immediate medical attention at a healthcare facility for definitive diagnosis and appropriate therapeutic management. Regarding vaccination strategies, clinical data demonstrate the efficacy of licensed tetravalent dengue vaccines in reducing disease incidence. However, while these vaccines remain accessible via private clinics and specific healthcare facilities, they have not yet been integrated into expanded program on Immunization.