The health landscape across Oceania is under close observation as public health agencies track several infectious disease outbreaks and emerging threats. From the warm, tropical islands grappling with dengue fever to countries battling whooping cough and maintaining vigilance against polio, staying informed and proactive is crucial for community well-being. This update brings you the latest developments as of early May 2026, highlighting ongoing efforts to manage and prevent the spread of these illnesses. ## Dengue Fever: A Persistent Threat Across the Pacific Dengue fever, a mosquito-borne illness, continues to pose a significant challenge in several Pacific island nations. This viral infection, spread primarily by Aedes mosquitoes, causes symptoms ranging from high fever and severe headache to muscle and joint pain, and in severe cases, can lead to life-threatening complications. The presence of different dengue virus types, known as serotypes (DENV-1, DENV-2, DENV-3, DENV-4), means that people can be infected multiple times. A secondary infection with a different serotype can increase the risk of severe dengue. **New Caledonia** is experiencing an ongoing outbreak, with 1,376 cases reported in 2026 as of May 4. The predominant serotype is DENV-1, and health authorities maintain a 'red alert' to signify high transmission and continued vigilance. The rising number of cases underscores the need for continuous mosquito control efforts and public awareness campaigns to eliminate breeding sites. Further east, **Samoa** is also battling a widespread dengue outbreak. During late April 2026, 159 new cases were identified, with both DENV-1 and DENV-2 serotypes co-circulating. Children under 15 years old are disproportionately affected, accounting for 74% of cases. Six new hospital admissions were reported, though fortunately, no intensive care admissions or deaths occurred in this period. The co-circulation of multiple serotypes is a concern, as it can increase the risk of more severe disease. Public health measures include enhanced surveillance and community education to reduce mosquito populations. **Tonga** declared a dengue epidemic in April, with 53 confirmed cases as of May 4. DENV-2 is the dominant serotype. Children aged 10-14, particularly boys, are the most affected group, with most cases concentrated in Tongatapu. Three individuals remain hospitalised, and no dengue-related deaths have been reported so far. The ‘red alert’ status highlights the urgent need for continued public health interventions to control the spread. Meanwhile, **New Zealand** reported five confirmed imported dengue cases and one under investigation in late April/early May. These cases were linked to travel from various Pacific islands, including the Cook Islands, Samoa, and Tonga, as well as Malaysia. This serves as a reminder that with international travel, diseases can easily cross borders, making robust surveillance crucial even in non-endemic areas. ## Pertussis (Whooping Cough): Protecting Our Youngest and Most Vulnerable Pertussis, commonly known as whooping cough, is a highly contagious bacterial infection that primarily affects the respiratory system. Characterized by severe, uncontrollable coughing fits, it can be particularly dangerous, even fatal, for infants and young children who are not fully vaccinated. Vaccination is the most effective way to prevent this serious illness. In the **Federated States of Micronesia**, the state of Pohnpei continues to see pertussis circulation. Four new cases were notified in late April, bringing the total to 40 cases (15 confirmed, 25 suspected) since January 2026. Young children and unvaccinated individuals remain at highest risk. Health authorities are actively engaged in enhanced surveillance, contact tracing, treatment, vaccination campaigns, and community outreach to curb the spread. **Guam** has also reported ongoing pertussis activity, with 23 cases identified since May 2025. Two new confirmed cases were reported in late April 2026. There are currently no hospitalizations or deaths. Public health efforts are focused on epidemiological investigations, contact tracing, and vaccination, with a strong emphasis on protecting infants, pregnant women, and close contacts, as these groups are most vulnerable to severe outcomes. **New Zealand** is also experiencing continued community transmission of whooping cough. In the week ending April 24, 2026, 38 cases were reported, an increase from the previous week, contributing to a total of 610 cases for 2026. The fluctuating weekly numbers indicate persistent circulation within communities. Maintaining high vaccination rates among children and adults, particularly those who will be in contact with infants, is critical to protecting the wider population and preventing severe illness. ## Polio: Global Eradication Efforts Face New Challenges Poliomyelitis, or polio, is a debilitating and potentially fatal disease caused by the poliovirus. While global efforts have brought the world to the brink of eradication, ongoing surveillance is vital to detect any resurgence or circulation, especially of vaccine-derived polioviruses (VDPV). **Papua New Guinea** continues to combat a polio outbreak declared in May 2025. Despite no new human cases of poliovirus infection since October 2025, environmental surveillance (testing wastewater) has recently detected traces of the virus. This indicates potential silent circulation, meaning the virus could be spreading without causing visible symptoms, which makes it harder to track. In response, PNG launched a third national vaccination campaign on April 27, 2026, targeting children from birth to 59 months, with a particular focus on areas with low vaccination coverage like Morobe, Enga, Central provinces, and the National Capital District. The goal is to achieve over 95% vaccination coverage to halt transmission. In a separate development, **Australia** detected circulating vaccine-derived poliovirus type 2 (cVDPV2) in wastewater samples from Perth, Western Australia, in mid-April 2026. This was found during routine environmental surveillance. Crucially, no clinical cases of polio have been reported, and there is no evidence of local transmission. Australian health authorities assess the risk to the population as very low due to the country's high vaccination coverage and its polio-free status since 2000. However, this detection underscores the importance of continuous environmental surveillance as an early warning system. Follow-up wastewater testing has been intensified, and vaccination promotion continues to ensure robust community protection. ## Other Health Alerts: From Diarrheal Diseases to Emerging Threats Beyond these major alerts, other health concerns are being monitored: **Diarrheal Diseases in Federated States of Micronesia:** The state of Yap has been on alert for diarrheal diseases for two consecutive weeks, with 19 cases reported in late April, an increase from the previous week. Cases have been reported from both the main hospital and outer island health centers. Laboratory tests confirmed various enteric pathogens, including Norovirus, Rotavirus, and pathogenic E. coli. Public health officials are promoting hygiene, sanitation, community awareness, and continuing surveillance to control the spread of these common, yet potentially serious, illnesses, especially in settings where access to clean water and sanitation can be challenging. **Hantavirus on a Cruise Ship (Global Context):** While not specific to Oceania, a significant global health alert involved a confirmed hantavirus case on the MV Hondius cruise ship. A British passenger is in critical condition in South Africa, and several other passengers developed severe symptoms, with three suspected deaths. The World Health Organization (WHO) is coordinating an international response, including contact tracing and investigations. Hantaviruses are typically spread to humans through contact with rodent droppings, urine, or saliva, not person-to-person. The WHO considers this a serious but contained event with a low risk to the general public, and currently, no travel restrictions are recommended. This highlights the vital role of international health collaboration in managing outbreaks with global reach. **Mpox (Monkeypox) Detected in Hawaii Wastewater:** On April 27, 2026, Clade I mpox virus was detected in wastewater samples from O'ahu, Hawaii – the first detection in the state. The positive sample came from a wastewater treatment facility serving the Pearl Harbor-Hickam military base. Importantly, no clinical cases of mpox have been reported, and there is no indication of community spread. Subsequent samples tested negative, and regular testing at major civilian sites also remains negative. Health authorities believe the risk to the general public is low but encourage at-risk individuals to get vaccinated and remain vigilant. Wastewater surveillance is an increasingly valuable tool for early detection of viruses circulating in a community, even without clinical cases. ## Staying Vigilant for Community Health These ongoing health alerts underscore the dynamic nature of infectious diseases and the continuous need for robust public health surveillance and response systems. For communities across Oceania and globally, preventing illness hinges on awareness, timely vaccination, good hygiene practices, and environmental control measures. Staying informed and adhering to public health advice are essential steps to protect yourself, your family, and your community from these evolving health challenges.