Epidemic and emerging disease alerts in the Pacific as of 17 March 2026

Highlights/updates since the last map was sent on PacNet on 10 March 2026:

Dengue

• Cook Islands: As of 09 March 2026, the dengue outbreak in the Cook Islands remains ongoing, with 1,193 cumulative confirmed, suspected and probable cases reported since the outbreak was declared on 22 May 2025. This includes 25 active cases and 806 recovered cases, with 53 cases hospitalised to date, most of whom have since been discharged, and one dengue‑related death reported. Transmission continues to affect Rarotonga and the Pa Enua, with 145 cases reported from the Pa Enua, indicating sustained geographic spread beyond the main island. In response, Te Marae Ora continues to implement intensified outbreak control measures under Operation Namu26, including peri‑focal and block spraying targeting hotspots, island‑wide clean‑up activities, larval source reduction, and sustained community engagement. The blue alert for DENV-1 and DENV-2 remains in effect. – Source: Dengue Situation Report #90, EpiWeek #11 shared with PPHSN Coordinating Body focal point on 17 March 2026.
• New Caledonia: As of 14 March 2026, dengue activity continues to intensify in New Caledonia, with 268 cases reported since 1 January 2026 with 51 local cases reported in EpiWeek 09 and EpiWeek 10. From the Situation report #4 DENV‑1 remains the predominant serotype among locally acquired cases. The mean age of cases is approximately 27 years, with a slight female predominance (sex‑ratio H/F: 0.8). A total of 23 municipalities has reported cases, with significant transmission in the northern and eastern parts of the territory. The blue alert for DENV-1 remains in effect. – Sources: Vigilance DASS Dengue 2026-#4 shared with PPHSN Coordinating Body Focal point on 10 March 2026 & La dengue | Direction des Affaires Sanitaires et Sociales de Nouvelle-Calédonie accessed on 17 March 2026.
• Samoa: As of 08 March 2026, Samoa continues to experience a prolonged dengue outbreak, with 17,402 cumulative clinically diagnosed cases and 5,117 laboratory‑confirmed cases reported since 01 January 2025. During EpiWeek 10 (02–08 March 2026), 187 new cases were notified, representing a 7% decrease compared with the previous week, alongside 10 new hospital admissions, with no new ICU admissions or dengue‑related deaths reported during the week. Transmission remains widespread, with 64% of cases reported from Upolu and 36% from Savaii, and children under 15 years accounting for 74% of all cases. The proportion of DENV‑2 among confirmed serotypes increased markedly, from 9% in EpiWeek 08 to 32% by EpiWeek 10, indicating a shift in serotype distribution alongside the continued predominance of DENV‑1. The cumulative number of reported dengue‑related deaths has been updated to nine, reflecting a revision from earlier reports. Health authorities continue outbreak response activities, including enhanced surveillance, risk communication and community engagement, while closely monitoring trends in severe disease and hospitalisation. The blue alert for DENV-1 and DENV-2 remains in effect. – Source: Dengue-sitrep-issue-no-47_Government of Samoa - Ministry of Health accessed on 17 March 2026.

Measles

• Australia: Measles activity in Australia continues in early 2026, largely driven by imported cases with evidence of subsequent local transmission. In South Australia, a third measles case was notified on 10 March 2026 in an unvaccinated infant with no recent travel history, prompting extensive public exposure notifications across healthcare, educational and community settings. In New South Wales (NSW), case numbers have continued to increase, with 29 confirmed cases reported since 1 January 2026, including several locally acquired cases with no identified source, indicating likely ongoing community transmission, particularly across metropolitan Sydney. Epidemiological investigations in NSW indicate that while the majority of cases remain linked to overseas travel predominantly to Southeast Asia an increasing proportion of cases are locally acquired, including sporadic cases not linked to known transmission chains. Public health authorities across affected jurisdictions continue to issue exposure alerts, reinforce early case detection and isolation measures, and emphasise the importance of vaccination to limit further spread. The red alert for measles in Australia remains in effect. – Sources: Measles case 10 March 2026 | SA Health, Measles alert for Sydney, NSW respiratory surveillance, and National Communicable Diseases Surveillance Dashboard accessed on 17 March 2026.

Pertussis/Whooping cough

• Federated States of Micronesia: As of 12 March 2026, pertussis activity continues in Pohnpei State, with 30 cumulative cases reported since 05 January 2026, including 14 laboratory‑confirmed and 16 suspected cases. This represents two additional cases since the previous update (05 March 2026), comprising one confirmed and one suspected case. The majority of cases have occurred among adults, with one newly reported paediatric case in a seven‑year‑old child. Cases remain geographically dispersed. Vaccination coverage remains low, with only two cases reported as up to date with pertussis immunisation, while most affected children and adults are unvaccinated. Laboratory testing confirms ongoing transmission of Bordetella pertussis, with concurrent detection of other respiratory co‑infections. No hospitalisations or deaths have been reported to date. Public health authorities continue enhanced surveillance, case investigation, contact tracing and risk communication, alongside targeted vaccination and booster promotion, particularly among frontline health workers and close contacts. A red alert for pertussis is added. – Source: Pertussis Situation Report, Issue no. 7 shared with PPHSN Coordinating Body Focal point on 13 March 2026.
• New Zealand: Pertussis activity in New Zealand continues as part of the ongoing national epidemic, with a recent increase in weekly notifications. As of the week ending 06 March 2026, 37 cases were reported, up from 28 cases in the previous week (ending 27 February), bringing the total number of reported cases in 2026 to 443. Since the start of the national epidemic on 19 October 2024, a total of 4,205 confirmed, probable, and suspected cases has been notified, with 392 cases (9.6%) requiring hospitalisation and one death reported. Infants under 1 year of age remain the most affected, with more than half of infant cases requiring hospitalisation. While recent case numbers are substantially lower than during the same period last year, health authorities continue to emphasise vaccination and sustained surveillance to protect high-risk groups. The blue alert for pertussis remains in effect. – Sources: Pertussis dashboard & Pertussis Report 7 February–6 March 2026 accessed on 17 March 2026.

Rotavirus

• Kiribati: The rotavirus outbreak in Kiribati remains substantial, with 4,508 cumulative cases reported as of 15 March 2026, but recent data indicate a continued stabilisation of transmission. Epidemiological trends suggest that the outbreak peaked in late February to early March, with the overall test positivity rate declining from approximately 80% to 67%, despite ongoing increases in reported suspected cases, including from outer islands such as Beru, Abaiang and North Tarawa. Transmission remains concentrated in South Tarawa, particularly Betio, which continues to report the highest case burden. Children under five years of age remain the most affected group, although cases span a wide age range (from six days to 89 years). To date, 54 patients have required hospitalisation, predominantly paediatric cases. Five deaths have been reported in association with the outbreak and remain under review. Health authorities continue enhanced surveillance, laboratory confirmation and monitoring of disease severity, alongside sustained risk communication, community hygiene promotion, extended clinic hours and decentralised service delivery, while closely monitoring for any resurgence in cases. The red alert for Rotavirus remains in effect. – Sources: Rota Virus Outbreak Situational Report 10 shared with PPHSN Coordinating Body Focal point on 17 March 2026.

Other Information:

Dengue

• Federated States of Micronesia: As of 12 March 2026, dengue activity in Chuuk State remains low with no new cases reported over the past three weeks and a cumulative total of 13 laboratory-confirmed cases among 53 patients screened since 12 November 2025. Confirmed cases have been reported from multiple locations with evidence of clustered transmission. The most recent confirmed cases have recovered, and no severe cases or dengue‑related deaths have been reported to date. Dengue‑like illness surveillance and rapid diagnostic testing remain ongoing, and specimens from confirmed cases have been sent overseas for dengue virus genotyping, with results pending. – Source: Chuuk Dengue Situation Report 9 (12 March 2026) shared with PPHSN Coordinating Body Focal point on 13 March 2026.
• New Zealand: In New Zealand (NZ), during EpiWeek 10 (07 March – 13 March 2026), ten confirmed imported dengue cases and five probable cases were reported. Among confirmed cases with a travel history, 100% had returned from the Cook Islands. The four probable cases with travel history had been to the Cook Islands (75%) and Indonesia (25%). Given the known serological cross‑reactivity between dengue and other flaviviruses, some reported dengue cases may ultimately be reclassified as other flavivirus infections as epidemiological and laboratory investigations continue. – Source: NZ Arbovirus Notifications by Country (10: 07/03/2026–13/03/2026) shared with PPHSN Coordinating Body Focal point on 16 March 2026.