A dengue outbreak that fell almost entirely on children

Dengue is a febrile disease caused by one of four dengue viruses (DENV-1 to
DENV-4), spread mainly by infected Aedes mosquitoes. In 2025, **11 of 21
Pacific Island countries and areas reported outbreaks**.

Naoero has a population of about 11,000 and one hospital — the
Republic of Naoero Hospital, with six emergency department beds and 65
inpatient beds. It had seen dengue in 2014 (251 cases, no deaths), 2017
(DENV-2; 964 cases, three deaths) and 2018 (DENV-1; 114 cases, no deaths), and
no cases at all during 2019–2024.

How it started

On 27 June 2025 a 16-year-old boy was seen at the hospital with fever,
headache, muscle and joint pain. Dengue was suspected from the symptoms and
the outbreaks elsewhere in the region, and a rapid diagnostic test came back
positive for dengue NS1 antigen. The next day a 17-year-old boy tested
positive for dengue IgM.

Clinicians were alerted, told to suspect dengue and to use the rapid test.
Within 10 days, 32 more laboratory-confirmed cases were identified. The
government declared an outbreak on 8 July.

What the outbreak looked like

Between 27 June and 28 September, 1,402 people with suspected dengue
were tested, and 477 (34%) were laboratory-confirmed.

Confirmed cases came from all 14 districts. Testing at the CDC identified
DENV-2, and phylogenetic analysis confirmed the **cosmopolitan genotype,
lineage 5**.

Why children. The report's own explanation is that the concentration among
the young is *likely related to high levels of previous DENV exposure and
immunity among adults*. The 2017 and 2018 outbreaks protected the people who
lived through them — and left everyone born or arriving since without that
protection. A country's dengue history is written into who falls ill next
time.

What one hospital did

• Refresher training on timely case identification and recommended
  clinical management
• A dengue triage tent for rapid assessment of febrile patients, against
  hospital overcrowding
• A nine-bed dengue unit added to the existing 65 beds
• Care at home for most patients, with regular check-ups by home visit
• Outpatient services suspended, with staff and supplies reassigned from
  other parts of the hospital

Alongside that: public messaging on repellent, removing standing water and
when to seek care; and vector control teams distributing larvicides and
repellents, spraying indoors in schools, in households with cases and in
neighbouring homes, and running community campaigns to clear standing water.

Cases began falling in the week of 22 August, the last confirmed case was
18 September, and the outbreak was declared over on 28 September 2025.

What it shows

A dengue epidemic is rapid and disruptive, and it strains a resource-limited
health system in ways the case count alone does not convey — an island
hospital closing its outpatient clinic to staff a dengue ward is the real
measure of it.

The report's conclusions: strengthen year-round vector control and
clinical training for managing children with dengue, improve **early
detection** through surveillance and laboratory testing, and build public
health capacity for outbreaks that are growing in frequency and size across
the Pacific Islands. And it underscores the need for **safe and effective
dengue vaccines**.

*Source: Sánchez-González L, Zebari D, Detenamo M, et al. Notes from the
Field: Dengue Outbreak — Naoero, 2025. MMWR Morb Mortal Wkly Rep
2026;75:413–415. Centers for Disease Control and Prevention.*