Tonga-Fiji: Dengue fever cases likely to climb amid increased rainfall and floods

On 24 March, Tonga’s Ministry of Health reported 339 dengue fever cases with the highest recorded in Vava’u. The Ministry of Health disclosed that the 10-19 age group were the most affected but no deaths had yet occurred. The Tongan Government declared a dengue fever outbreak on 19 February 2025. Separately, the Fijian Ministry of Health announced the death from  dengue fever in the Northern Division. An  outbreak has officially been ongoing in the Western Division since 3 February 2025. Both countries have established measures to control the spread of the disease, including targeted interventions, eliminating breeding sites, and the use of protective measures.

Assessment: The surge in dengue fever cases is likely a result of repeated rains in Tonga and Fiji. Other Pacific island countries are very likely to record dengue fever cases due to similar weather. A high number of adolescent cases indicates a lack of sufficient preventive measures and an exposure to mosquitoes at secondary school institutions. Poor drainage systems and sanitation problems have been reported as likely mosquito breeding sites. Health Ministries will very likely embark on massive preventive containment measures in most affected areas to control the spread of the disease.

Sources:  “Tonga declares dengue outbreak amid rising cases,” RNZ, February 19, 2025; “Tonga's dengue cases surge to 339, health ministry says,” RNZ, March 25, 2025; “Epidemic and emerging disease alerts in the Pacific as of 25 March 2025,” ReliefWeb, March 25, 2025; Shania Shayal Prasad, “Surge in flu and dengue cases,” FBC, March 18, 2025.