World: Epidemic and emerging disease alerts in the Pacific as of 31 March 2026

Executive Summary

Countries: World, Australia, Cook Islands, Guam, Kiribati, Micronesia (Federated States of), New Caledonia (France), New Zealand, Palau, Samoa, Vanuatu, Wallis and Futuna (France) Source: Pacific Community Please refer to the attached Map. Highlights/updates since the last map was sent on PacNet on 24 March 2026: Dengue Cook Islands: As of 26 March 2026, the dengue outbreak in the Cook Islands remains ongoing, with transmission continuing to be reported from Rarotonga and Aitutaki. Over the past seven days, 15 new cases were reported from Rarotonga and one case from Aitutaki, bringing the number of active cases to 19, with no dengue-related hospital admissions reported in the past three weeks. In contrast, Atiu has reported no cases for six consecutive weeks, Mauke for four weeks, and Mangaia is entering its third week without reported cases, suggesting a reduction in transmission in the Pa Enua. Outbreak response activities under Operation Namu26 continue, including perifocal spraying, larval surveillance, environmental cleanup, and community engagement, alongside ongoing dengue pack distribution across affected islands. The blue alert for DENV-1 and DENV-2 remains in effect. – Source: Operation Namu26 Weekly Update 7 - Te Marae Ora Cook Islands Ministry of Health accessed on 31 March 2026. New Caledonia: As of 25 March 2026, dengue activity in New Caledonia has intensified, with 394 cases reported since 1 January 2026, including 357 confirmed autochthonous cases, 33 probable autochthonous cases, three confirmed imported cases and one clinically diagnosed case, corresponding to an overall incidence rate of 66 cases per 100,000 population. Transmission has prompted the declaration of an epidemic phase, with sustained and rapidly increasing transmission observed outside the Grand Nouméa area, while transmission within Grand Nouméa (Dumbéa, Mont-Dore Nouméa, Païta) remains relatively low and stable, consistent with the protective effect of the World Mosquito Program. Thirteen patients required hospitalisation, with a mean age of 40 years, no admissions to intensive care, no reported severe disease, and all patients have since been discharged. DENV‑1 continues to be the predominant circulating serotype. The blue alert for DENV-1 is changed for a red alert. – Sources: Alerte DASS Dengue_20260325 shared with PPHSN Coordinating Body Focal point on 26 March 2026 & La dengue | Direction des Affaires Sanitaires et Sociales de Nouvelle-Calédonie accessed on 31 March 2026. Samoa: As of 22 March 2026, Samoa continues to experience a prolonged dengue outbreak, with 17,778 cumulative clinically diagnosed cases and 5,234 laboratory‑confirmed cases reported since 1 January 2025. During EpiWeek 12 (16–22 March 2026), 64 laboratory confirmed cases were reported, representing a 21% increase compared with the previous week, while 23 new hospital admissions were recorded. No ICU admissions or dengue‑related deaths were reported during the EpiWeek 12. The cumulative number of dengue‑related deaths remains nine. DENV‑1 remains the predominant serotype (68%), followed by DENV‑2 (32%), with transmission remaining widespread across Upolu (64%) and Savaii (36%). Children under 15 years account for 74% of all reported cases. The blue alert for DENV-1 and DENV-2 remains in effect. – Source: Dengue Fever Outbreak Situation Report in Samoa Issue No 49 shared with PPHSN Coordinating Body Focal point on 25 March 2026. Measles Australia: Measles activity in Australia continues in early 2026, driven primarily by imported cases with growing evidence of local transmission, particularly in New South Wales (NSW), Queensland and Victoria. As of late March 2026, 38 measles cases have been confirmed in NSW since 1st January, including several locally acquired cases, some with no identified source of infection, indicating ongoing community transmission. While Queensland has reported 15 cases to date, comprising both imported and locally acquired infections linked to exposure events at public venues and transport hubs. Public health authorities have issued multiple exposure alerts, intensified contact tracing, and continue to emphasise early case detection, isolation, and up‑to‑date measles vaccination, particularly for travellers and under‑immunised populations, to limit further spread. The red alert for measles in Australia remains in effect. – Sources: Measles alert for the Brisbane International Airport | Queensland Health, Measles alert for Gold Coast | Queensland Health, Measles alert for Wollongong, and National Communicable Diseases Surveillance Dashboard accessed on 31 March 2026. Pertussis/Whooping cough Federated States of Micronesia: As of 20 March 2026, pertussis activity continues in Pohnpei State, with 34 cumulative cases reported since 5 January 2026, including 14 laboratory‑confirmed and 20 suspected cases. This represents four additional suspected cases since the previous update (12 March 2026). Most cases have occurred among adults, with only one newly reported paediatric case in a five‑year‑old child. Cases remain geographically dispersed across the state. Pertussis vaccination coverage among children aged 19–39 months remains low at 39%, and most affected children and adults are unvaccinated. Laboratory testing confirms ongoing Bordetella pertussis transmission with respiratory co‑infections. No hospitalisations or deaths have been reported to date, and enhanced surveillance, contact tracing, risk communication, and targeted vaccination and booster promotion are ongoing. The red alert for pertussis in Pohnpei remains in effect. – Source: Pertussis Situation Report, Issue no. 8 shared with PPHSN Coordinating Body Focal point on 26 March 2026. New Zealand: Pertussis activity in New Zealand continues as part of the ongoing national epidemic, although recent weekly notifications have declined. As of the week ending 20 March 2026, 18 cases were reported, down from 28 cases the previous week, bringing the total number of cases reported in 2026 to 492. The blue alert for pertussis remains in effect. – Sources: Pertussis dashboard accessed on 31 March 2026. Vanuatu: As of 30 March 2026, three new pertussis cases were reported in Vanuatu between EpiWeeks 10 - 12. This brings the cumulative total to 811 cases since the outbreak was declared on 18 August 2025, including 780 clinically diagnosed and 31 laboratory‑confirmed cases. Pertussis activity in 2026 continues to show a declining trend compared with late 2025, although case numbers remain above the alert threshold, indicating ongoing transmission. The cumulative number of pertussis‑associated deaths remains seven, including six in Tanna and one in Shefa, with 67 hospitalisations reported to date and no current hospitalisations. Cases have been reported across all age groups, with the highest burden among children aged 1–9 years and a substantial proportion among infants under one year of age. Among cases with known vaccination status, 47% were unvaccinated, while 53% had received at least one dose of a pertussis‑containing vaccine. Transmission remains concentrated in Efate (~54%) and Tanna (~38%). Enhanced surveillance continues as the outbreak remains ongoing. The blue alert for pertussis remains in effect. – Sources: Source: Vanuatu Pertussis Outbreak: Situation Report 16 (30 March 2026) shared on PacNet on 31 March 2026. Rotavirus Kiribati: As of 26 March 2026, the rotavirus outbreak in Kiribati remains ongoing, with 5,350 cumulative diarrhoea cases reported, reflecting a continued circulation since mid‑March. While transmission has declined substantially in recent days, with daily suspected cases decreasing to low levels by late March, the outbreak continues to disproportionately affect South Tarawa, particularly Betio, which accounts for the largest share of reported cases. Children under five years of age remain the most affected, with 56 hospitalisations reported to date, and three confirmed deaths and two suspected deaths currently under investigation. Health authorities continue enhanced surveillance, laboratory confirmation, health promotion, and community‑level hygiene interventions while closely monitoring trends. The red alert for Rotavirus remains in effect***.** – Sources: Rotavirus Outbreak Situational Report 14 shared with PPHSN Coordinating Body Focal point on 30 March 2026.* Other Information: Ciguatera Vanuatu: As of 30 March 2026, ciguatera fish poisoning activity in Vanuatu remains ongoing, with 11 new cases reported, bringing the cumulative total to 75 cases nationally. Case numbers declined slightly between EpiWeeks 09 and 11 and remained below the alert threshold during that period, before exceeding the alert threshold again in EpiWeek 12. No deaths were reported, and one case was hospitalised and subsequently discharged, with no current hospitalisations. Males accounted for 60% of cases, and individuals aged 15–34 years were the most affected. Cases were reported across eight islands, predominantly Efate (63%), and most illnesses were linked to consumption of unspecified “other” fish, followed by reef fish and Karosol fish. – Source: Vanuatu Ciguatera Situation Report 4 shared on PacNet on 31 March 2026*.*** Dengue Hawai’i: As of 27 March 2026, the Hawaiʻi Department of Health reported a new travel‑related dengue virus case on Oʻahu, bringing the total number of dengue cases reported in the state to four in 2026. The case was acquired overseas in a dengue‑endemic area, and no local transmission has been identified to date. Public health authorities note that recent heavy rainfall may increase mosquito breeding and underscore the importance of source reduction. In response, vector control teams have conducted inspections and community outreach, while the public is encouraged to eliminate standing water and travellers returning from dengue‑affected areas are advised to take precautions to prevent mosquito exposure. – Source: DOH REPORTS ANOTHER TRAVEL-RELATED DENGUE VIRUS CASE ON OʻAHU | News Releases from Department of Health accessed on 31 March 2026. New Zealand: In New Zealand (NZ), during EpiWeek 12 (21 – 27 March 2026), five confirmed imported dengue cases and one case under investigation were reported. Among confirmed cases with a travel history, 60% had returned from the Cook Islands and 40% from Samoa. 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 (12: 21/03/2026–27/03/2026) shared with PPHSN Coordinating Body Focal point on 30 March 2026. Wallis and Futuna: As of 20 March 2026, a travel‑related dengue case was confirmed in Wallis and Futuna, identified at Sia Hospital in a person who had recently arrived in the territory. The case was promptly managed by health authorities, with the patient placed under isolation, enhanced epidemiological surveillance implemented, and vector control measures conducted within a 150‑metre radius of the residence, including larval source reduction and targeted mosquito control. – Source: Un cas de dengue importé à Wallis et Futuna accessed on 31 March 2026. Diphtheria Australia: Health authorities in Australia’s Northern Territory have reported four cases of respiratory diphtheria, including three cases in Darwin and one in Alice Springs, triggering an urgent public health response. Since 2025, 33 cases of cutaneous toxigenic diphtheria have also been notified, indicating ongoing circulation of toxigenic Corynebacterium diphtheriae. Enhanced surveillance, contact tracing, and infection prevention and control measures are underway, and clinicians are urged to remain vigilant, particularly among under‑ or unvaccinated individuals, while ensuring vaccination status is up to date. – Sources: CDC surveillance update - March 2026 and Public health alert - diphtheria outbreak in the NT - 25 March 2026 accessed on 31 March 2026. Gastroenteritis Palau: As of 29 March 2026, gastroenteritis activity in Palau has continued to increase, with 28 acute gastroenteritis cases reported in EpiWeek 13 (23-29 March 2026), up from 17 cases in the previous week and approaching the alert threshold of 30 cases. The Ministry of Health and Human Services has reported that several cases are suspected to be associated with norovirus, prompting the issuance of a public service announcement and reinforcement of hygiene, food safety, and environmental sanitation measures. Enhanced surveillance and laboratory monitoring are ongoing to assess trends and support timely public health response. – Source: Ministry of Health & Human Services Syndromic Surveillance EpiWeek 13 shared with PPHSN Coordinating Body focal point on 30 March 2026. Influenza-Like Illness Kiribati: As of 25 March 2026, Kiribati has reported a cumulative total of 552 influenza‑like illness (ILI) cases, primarily affecting South Tarawa, particularly Betio. The epidemic curve indicates a rapid increase in cases from mid‑March, peaking around 18–20 March with part of the increase attributed to delayed healthcare‑seeking and retrospective reporting. The median age of cases is four years (range: 1 month to 89 years), cases are evenly distributed by sex (51% female, 49% male), and one ILI‑associated death is currently under investigation. Laboratory testing has confirmed six influenza B cases. Health authorities have strengthened surveillance and community awareness activities while continuing to monitor trends. – Source: ILI Outbreak Situational Report 11 shared with PPHSN Coordinating Body Focal point on 18 March 2026 Norovirus Federated States of Micronesia: Norovirus transmission remains ongoing in Pohnpei State, with 18 cumulative cases reported as of 20 March 2026, including three new cases since the previous update. The outbreak, first detected on 28 January 2026, continues to disproportionately affect young children, with 72% of cases occurring among children under five years of age (age range: 4 days to 57 years), and a high proportion of cases (83%) requiring hospitalisation. Two deaths have been reported to date, both among hospitalised paediatric cases. Cases remain geographically dispersed across the state, particularly in Kitti and Sokehs. Laboratory investigations confirm ongoing norovirus transmission with co‑detection of other gastrointestinal pathogens. – Source: Norovirus Outbreak Report No.5 shared with PPHSN Coordinating Body Focal point on 26 March 2026. Pertussis/Whooping cough Guam: Pertussis continues to be reported in Guam, with the Department of Public Health and Social Services confirming one new laboratory‑confirmed case on 25 March 2026, bringing the total number of confirmed cases in 2026 to seven. Epidemiological investigation and contact tracing are ongoing to determine the source of exposure and prevent further transmission, and no additional clusters have been reported to date. Public health authorities continue to monitor respiratory illness trends and reinforce vaccination messaging, particularly for infants, pregnant women, and close contacts, to reduce the risk of further spread. – Sources: news_1774423298_PR26-079 DPHSS Confirms One New Case of Pertussis in Guam.pdf and Guam Communicable Disease Dashboard accessed on 24 March 2026.