Dengue Fever Outbreak: Cook Islands, New Caledonia, Samoa & Micronesia – March 2026

Dengue fever continues to be a public health concern across several Pacific Island nations, with ongoing outbreaks in the Cook Islands and Samoa, and increasing circulation in New Caledonia. As of March 19, 2026, health authorities are closely monitoring the situation and advising travelers and residents to take precautions against mosquito bites.

Cook Islands: Sustained Transmission

In the Cook Islands, 1,193 confirmed, suspected, and probable cases of dengue have been recorded since the start of the epidemic on May 22, 2025, extending through March 9, 2026. Transmission is ongoing in Rarotonga and the outer islands (Pa Enua). The circulating strains are DENV-1 and DENV-2. Dengue is a viral infection transmitted by Aedes mosquitoes, and symptoms typically include high fever, severe headache, muscle and joint pain, rash, and sometimes bleeding. While most cases are mild, severe dengue can lead to hospitalization and even death. You can find more information about dengue from the Mesvaccins.net website.

New Caledonia: Intensifying Circulation

New Caledonia is experiencing an intensification of dengue circulation, with 268 cases reported between January 1 and March 14, 2026. Of these, 51 were locally acquired during epidemiological weeks 9 and 10. DENV-1 remains the predominant serotype in locally acquired cases, with significant transmission occurring in the north and east of the country. The province of Îles Loyauté has issued a call for vigilance, noting two confirmed autochthonous cases in Lifou, specifically in the Xepenehe area. La 1ère reports that residents are being urged to eliminate standing water and protect themselves from mosquito bites.

Samoa: Prolonged Epidemic with Shifting Serotypes

Samoa continues to grapple with a prolonged dengue epidemic. Between January 1, 2025, and March 8, 2026, a total of 17,402 cases have been clinically diagnosed, with 5,117 confirmed by laboratory testing. During the week of March 2-8, 2026 (epidemiological week 10), 187 new cases were reported, a 7% decrease from the previous week, along with ten new hospitalizations. Transmission remains widespread, with 64% of cases reported in Upolu and 36% in Savaii. Notably, the proportion of DENV-2 among confirmed cases has increased significantly, rising from 9% in epidemiological week 8 to 32% in week 10. While DENV-1 remains the most prevalent serotype, this shift in serotype distribution is being closely watched by public health officials.

Micronesia: Low-Level Circulation in Chuuk

In the Federated States of Micronesia, dengue continues to circulate at a low level in the state of Chuuk as of March 12, 2026. No new cases have been reported in the last three weeks. Of the 53 people tested since November 12, 2025, 13 cases have been laboratory confirmed, with some data suggesting localized outbreaks.

Understanding Dengue Serotypes and Implications

Dengue virus has four distinct serotypes (DENV-1, DENV-2, DENV-3, and DENV-4). Infection with one serotype provides immunity to that specific serotype, but not to the others. Sequential infection with different serotypes increases the risk of developing severe dengue. The observed increase in DENV-2 circulation in Samoa is therefore a concern, as individuals previously infected with DENV-1 may be more vulnerable to severe illness if exposed to DENV-2. This highlights the importance of ongoing surveillance to track serotype distribution and inform public health strategies.

Public Health Response and Prevention

Public health authorities in the affected regions are implementing various measures to control the spread of dengue, including mosquito control programs, public awareness campaigns, and clinical management of cases. Mosquito control efforts typically focus on eliminating breeding sites, such as standing water in containers, and using insecticides to reduce mosquito populations. Public awareness campaigns emphasize personal protective measures, such as using mosquito repellent, wearing long sleeves and pants, and sleeping under mosquito nets. The government of New Caledonia has also highlighted the importance of these measures, noting that the rainy season creates favorable conditions for mosquito breeding. More information on dengue in New Caledonia can be found on the DASS Nouvelle-Calédonie website.

What to Expect Next: Surveillance and Guidance Updates

Continued surveillance is crucial for monitoring the evolution of these outbreaks and informing public health interventions. Health organizations will continue to track case numbers, serotype distribution, and geographic spread of the virus. This data will be used to assess the effectiveness of control measures and adjust strategies as needed. Guidance for travelers and residents may be updated based on the latest epidemiological information. Individuals experiencing symptoms consistent with dengue fever should seek medical attention promptly. There is currently no widely available vaccine for dengue, so prevention remains the most effective strategy. The World Health Organization (WHO) provides comprehensive information on dengue, including global updates and guidance on prevention and control, available at their website.