World: Epidemic and emerging disease alerts in the Pacific as of 28 April 2026

Executive Summary

Countries: World, Australia, Cook Islands, French Polynesia (France), Guam, Kiribati, Micronesia (Federated States of), New Caledonia (France), New Zealand, Palau, Tonga, United States of America, Vanuatu Source: Pacific Community Please refer to the attached Map. Highlights/updates since the last map was sent on PacNet on 21 April 2026: Dengue Cook Islands: As of 24 April 2026, dengue activity in the Cook Islands has remained low, with only isolated cases reported and no evidence of sustained transmission. Between 6 and 22 April 2026, single cases were reported on 9, 13, 14 and 20 April, all on Rarotonga, while no cases have been reported from Aitutaki or Atiu during the past month and none from Mauke and Mangaia for several months. Given the sustained reduction in reported cases, Operation Namu26 has concluded, and routine public health surveillance and monitoring are continuing as authorities work towards a possible declaration of dengue‑free status. The blue alert for DENV-1 and DENV-2 remains in effect. – Source: Operation Namu26 Weekly Update 10 - Te Marae Ora Cook Islands Ministry of Health accessed on 28 April 2026. New Caledonia: As of 27 April 2026, dengue transmission in New Caledonia remains ongoing, with 1,190 cases reported in 2026, indicating continued epidemic activity. The most recent case was reported on 27 April 2026. DENV‑1 remains the predominant circulating serotype. The red alert for DENV-1 remains in effect. – Source: La dengue | Direction des Affaires Sanitaires et Sociales de Nouvelle-Calédonie accessed on 28 April 2026. Samoa: As of EpiWeek 16 (13–19 April 2026), Samoa continues to experience ongoing dengue transmission. During the week, 29 laboratory‑confirmed cases were reported, representing an increase compared with the previous week, while 121 clinically diagnosed cases were recorded. Fifteen new hospital admissions were reported, with no ICU admissions and no dengue‑related deaths. DENV‑1 (57%) and DENV‑2 (43%) continue to co‑circulate, and transmission remains widespread across Upolu and Savai‘i, with children under 15 years continuing to be the most affected age group. The cumulative number of dengue-related deaths remains nine. The blue alert for DENV-1 and DENV-2 remains in effect. – Source: Dengue Fever Outbreak Situation Report in Samoa Issue No 53 shared with PPHSN Coordinating Body Focal point on 24 April 2026. Tonga: As of 28 April 2026, dengue transmission continues in Tonga following the outbreak declaration earlier in April. A total of 41 laboratory-confirmed cases have been reported, including two new cases since the 27 April. Case distribution by age group and island remains unchanged, with most cases reported among children aged 11–14 years, predominantly male and mainly from Tongatapu. One case remains hospitalised, with no dengue-related deaths reported. The dengue red alert remains in place, with DENV-2 confirmed as the circulating serotype. – Source: Dengue Fever Outbreak Situation Report #10 - Ministry of Health Tonga - Official Facebook page accessed on 28 April 2026. Measles Australia: Measles activity continues in Australia and remains largely linked to imported cases and secondary spread. As of late April 2026, cases have been reported in New South Wales and Victoria, mainly associated with recent international travel. In New South Wales, recent cases in Sydney have been linked to returned travellers from Japan and South-East Asia, with multiple public exposure locations identified. In Victoria, recent cases were infectious while attending multiple public exposure sites, including healthcare settings and public venues, prompting exposure alerts. Most cases continue to occur among under-vaccinated or individuals of unknown vaccination status, and authorities continue to emphasise the importance of two-dose MMR vaccination, particularly prior to overseas travel. The red alert for measles in Australia remains in effect. – Sources: Measles alert for Sydney, Measles public exposure sites in Victoria | health.vic.gov.au and National Communicable Diseases Surveillance Dashboard accessed on 28 April 2026. Pertussis/Whooping cough Federated States of Micronesia: As of EpiWeek 16 (13–19 April 2026), pertussis transmission continues in Pohnpei State. Seven new cases were reported during the reporting period, bringing the cumulative total to 36 cases since January 2026, including 14 laboratory‑confirmed and 22 suspected cases. Cases have been reported across multiple communities, with unvaccinated individuals, including children, remaining disproportionately affected. No hospitalisations or deaths have been reported to date. Health authorities continue enhanced surveillance, contact tracing, community awareness, and vaccination activities. The blue alert for pertussis remains in effect*. – Source: Communicable Disease Weekly Bulletin (report for EpiWeek: 16) shared with PPHSN Coordinating Body Focal point on 24 April 2026.* Guam: As of 22 April 2026, pertussis transmission continues in Guam. A total of 20 cases have been reported since EpiWeek 21 of 2025, including 19 laboratory‑confirmed and one probable case. Of these, 11 laboratory‑confirmed cases have been reported in 2026 to date, including two new cases identified in mid‑April. One case has been hospitalised, and no pertussis‑related deaths have been reported. Public health authorities continue case investigation, contact tracing, and vaccination activities, with a focus on infants, pregnant women, and close contacts. The red alert for pertussis remains in effec*t – Sources: Pertussis Outbreak Situation Report N°4 shared on PacNet on 23 April 2026 and* news_1776946451_DPHSS Public Health Advisory Typhoon Recovery No. 2026-11_DPHSS Confirms Two New Cases of Pertussis in Guam.pdf and Epi Reports | Epidemiology and Laboratory Capacity (ELC) Guam – DPHSS accessed on 28 April 2026. New Zealand: Pertussis activity in New Zealand shows ongoing transmission. As of the week ending 17 April 2026, 25 cases were reported, an increase compared with nine cases reported in the previous week. This brings the total number of reported cases in 2026 to 571. Weekly notifications continue to fluctuate, indicating sustained community transmission. The blue alert for pertussis remains in effect. – Source: Pertussis dashboard accessed on 28 April 2026. Vanuatu: As of EpiWeek 16 2026, pertussis transmission in Vanuatu remains ongoing but continues to show a declining trend compared with the peak in late 2025. Two new laboratory-confirmed cases were reported in EpiWeek 14, both from Efate, bringing the cumulative total to 827 cases, including 784 clinically diagnosed and 43 laboratory-confirmed cases. The cumulative number of deaths remains seven, with six deaths reported in Tanna and one in Shefa, and no current hospitalisations. Cases continue to affect all age groups, with the highest burden among children aged 1–9 years and a substantial proportion among infants under one year of age, while 48% of cases with known vaccination status remain unvaccinated. Transmission remains concentrated in Efate (~54%) and Tanna (~38%), and enhanced surveillance continues to ensure the outbreak is fully controlled. The blue alert for pertussis remains in effect. – Sources: Source: Vanuatu Pertussis Outbreak: Situation Report 18 (20 April 2026) shared on PacNet on 24 April 2026. Rotavirus Kiribati: As of 27 April 2026, the rotavirus outbreak in Kiribati remains ongoing, with 6,239 cumulative diarrhoea cases reported nationwide. Surveillance data indicate that the outbreak peaked in early March and cases have declined steadily since mid‑to‑late March, although low‑level transmission continues into April. Transmission remains concentrated in South Tarawa, particularly Betio, which continues to account for the largest proportion of cases. Children under five years of age remain the most affected, with 56 hospitalisations reported to date. The cumulative number of deaths includes three confirmed deaths and two suspected deaths under investigation. Enhanced surveillance, laboratory confirmation, health promotion, and community‑level hygiene interventions remain in place. The red alert for Rotavirus is changed for a blue alert***.** – Source: Rotavirus Outbreak Situational Report 19 shared with PPHSN Coordinating Body Focal point on 27 April 2026.* Other Information: Ciguatera Vanuatu: As of EpiWeek 16 2026, ciguatera fish poisoning activity in Vanuatu remains ongoing. Twenty‑five new cases were reported between EpiWeeks 15 and 16, bringing the cumulative total to 112 cases nationally. Case numbers have continued to increase and remain above the alert threshold since EpiWeek 14. No deaths or hospitalisations were reported during this period. Males accounted for 61% of cases, and individuals aged 15–34 years were the most affected. Cases were reported across nine islands, with Efate accounting for the largest proportion (63%). Most cases were linked to consumption of unspecified “other” fish, followed by reef fish and Karosol fish, with smaller numbers associated with other fish species. Ongoing surveillance continues, and authorities are closely monitoring trends. – Source: Vanuatu Ciguatera Situation Report 6 shared on PacNet on 24 April 2026*.*** Dengue New Zealand: In New Zealand (NZ), during EpiWeek 16 (18 – 24 April 2026), five confirmed imported dengue cases and one case under investigation were reported. Among confirmed cases, two had returned from Samoa, one from the Cook Islands, one from Tonga and one from Malaysia. 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 (16: 18/04/2026–24/04/2026) shared with PPHSN Coordinating Body Focal point on 28 April 2026. Wallis and Futuna: On 22 April 2026, one locally acquired dengue case was confirmed in Futuna, marking evidence of local transmission on the island. The patient had no recent travel history, supporting indigenous circulation of the virus, and was managed under isolation. To date, only two dengue cases have been reported in the territory in 2026, including one imported case in Wallis in March and this locally acquired case in Futuna. Transmission is currently documented only in Futuna, although undetected circulation in Wallis cannot be excluded. In Futuna, dengue transmission is primarily associated with Aedes polynesiensis, which is present on the island. Health authorities have implemented enhanced surveillance and vector control measures, including larval habitat reduction around the case household, and continue to monitor the situation closely, particularly given regional transmission in New Caledonia and the high proportion of asymptomatic dengue infections. – Sources: Email circulated on PacNet by the country focal point on 24 April 2026 and Dengue à Wallis et Futuna : comprendre les risques et la transmission du virus accessed on 28 April 2026. Measles Bangladesh: Measles transmission in Bangladesh remains widespread and intense. Between 15 March and 14 April 2026, more than 19,000 suspected cases and nearly 3,000 laboratory‑confirmed cases were reported across 58 of 64 districts, with 166 suspected measles‑related deaths, mainly among children under five years of age. A nationwide measles–rubella vaccination campaign began in early April, with further scale‑up underway. Continued transmission, combined with high population mobility and air travel, increases the likelihood of international importation. For Pacific Island Countries and Territories, the risk lies in introduction into settings with immunity gaps and limited response capacity, where outbreaks can spread rapidly. High two‑dose vaccine coverage, early case detection, and rapid public health response remain essential. – Source: Measles - Bangladesh_Disease Outbreak News - WHO accessed on 28 April 2026. Japan: Measles activity has increased in Japan in early 2026, with 299 cases reported nationally as of mid-April, exceeding the total reported in 2025. Cases have been notified from more than 20 prefectures, including Tokyo, with evidence of both imported infections and domestic transmission, including school-related clusters. Continued transmission in Japan, combined with high travel volumes and mass gathering events planned in 2026, increases the likelihood of further imported measles cases. – Sources: IDWR No. 14 <Notable Infectious Diseases> Measles|National Institute for Health and Crisis Management Infectious Disease Information Site and https://id-info.jihs.go.jp/surveillance/idwr/diseases/measles/graph/2026/meas26-15.pdf accessed on 28 April 2026. New Zealand: In April 2026, New Zealand reported a new locally acquired measles case in Wellington, with no identified links to overseas travel or previous cases. The case was infectious while visiting multiple public locations, including workplaces, hospitality venues, and event sites, leading to the identification of several locations of interest across the lower North Island. The source of infection is under investigation. Health authorities have implemented contact tracing, public exposure notifications, and enhanced surveillance, and continue to urge the public to check measles–mumps–rubella vaccination status. – Source: New measles case in Wellington, locations of interest identified accessed on 28 April 2026.