The global health landscape is in constant motion, with public health agencies continually monitoring and responding to outbreaks of infectious diseases. The latest alerts from Oceania and beyond highlight a dynamic situation, with persistent challenges from known diseases like dengue and pertussis, as well as emerging threats such as diphtheria and Murray Valley Encephalitis. Furthermore, a serious Ebola outbreak in Central Africa underscores the need for global vigilance and coordinated responses. ## Dengue Fever: A Persistent Threat in the Pacific Dengue fever, often called 'breakbone fever' due to the severe muscle and joint pain it can cause, is a mosquito-borne illness prevalent in tropical and subtropical regions. Transmitted by *Aedes aegypti* and *Aedes albopictus* mosquitoes, dengue can cause high fever, severe headache, rash, and in its most serious form, dengue hemorrhagic fever or dengue shock syndrome, which can be fatal. Several Pacific nations are currently navigating dengue outbreaks, each with unique circumstances. In a positive development, the **Cook Islands** have officially declared themselves dengue-free as of May 25, 2026. This welcome news follows a period of no new cases since April 28, 2026, exceeding the required two incubation periods. This success is attributed to sustained surveillance and robust mosquito control efforts, demonstrating the effectiveness of timely and coordinated public health interventions. Despite this declaration, routine monitoring and vector control activities are ongoing to prevent future reintroductions of the virus. Conversely, **Kiribati** continues to battle an ongoing dengue outbreak that began in April 2025. With a total of 535 biologically confirmed cases and 1,583 suspected cases reported by May 26, 2026, the disease remains concentrated in South Tarawa. Both DENV-1 and DENV-2 serotypes are circulating. While most cases have been mild, there has been one death and 68 hospitalizations, emphasizing the potential severity of the illness. **New Caledonia** is also experiencing significant dengue circulation, with 1,837 cases reported since the beginning of 2026. Local transmission is driving this epidemic, predominantly with the DENV-1 serotype. Environmental factors like heavy rainfall, which create abundant mosquito breeding sites, combined with population movement, continue to facilitate the spread. Health authorities are urging residents to seek medical attention promptly if symptoms appear and to actively engage in mosquito control measures around their homes. **Samoa** has seen widespread dengue activity, with 141 new cases reported in a single week in mid-May 2026, an increase from the previous week. Since January 1, 2025, the country has recorded over 19,000 clinically diagnosed and 5,446 laboratory-confirmed cases, alongside nine related deaths. The co-circulation of DENV-1 and DENV-2 serotypes persists, with children under 15 years being the most affected demographic. Public health strategies remain focused on community awareness and vector control. In **Tonga**, dengue circulation continues, with 66 confirmed cases reported by May 25, 2026. The DENV-2 serotype is responsible for the current outbreak, primarily affecting children aged 11 to 14, mostly boys, on the island of Tongatapu. Community sensitization campaigns and mosquito control are vital components of the response. Beyond these active outbreaks, other regions like the **Federated States of Micronesia (Kosrae State)** and **Vanuatu** are under close surveillance for dengue, reporting sporadic cases and maintaining vigilance. **New Zealand** has also reported imported dengue cases from travelers returning from affected areas, highlighting the interconnectedness of global health. The cornerstone of dengue prevention lies in controlling the *Aedes* mosquito population through eliminating breeding sites, using insect repellents, and wearing protective clothing. ## Whooping Cough: New Zealand's Ongoing Battle Pertussis, commonly known as whooping cough, is a highly contagious respiratory infection caused by the bacterium *Bordetella pertussis*. It spreads through airborne droplets from coughing or sneezing and is characterized by severe, uncontrollable coughing fits, often followed by a distinctive 'whooping' sound as the person tries to inhale. While it can affect anyone, pertussis is particularly dangerous for infants, leading to complications like pneumonia, brain damage, or even death. **New Zealand** is currently experiencing an ongoing pertussis epidemic, with cases continuing to circulate nationwide. In the week ending May 15, 2026, 48 new cases were reported, bringing the total for 2026 to 734. This continued rise underscores the importance of vaccination as the most effective preventive measure. Health authorities consistently recommend that pregnant women get vaccinated to pass on protective antibodies to their newborns, and that infants and children receive their scheduled pertussis immunizations. ## Diphtheria's Resurgence in Australia Diphtheria is a serious bacterial infection caused by *Corynebacterium diphtheriae*, which produces a potent toxin. This toxin can lead to a thick, grey membrane forming in the throat, making breathing difficult, and can also damage the heart, kidneys, and nerves. While often associated with respiratory symptoms, diphtheria can also manifest as skin lesions, known as cutaneous diphtheria. **Australia** has witnessed a concerning increase in diphtheria cases since late 2025, with 221 confirmed cases between January 1 and May 18, 2026. This marks a significant rise compared to previous years. The outbreak is concentrated in the Northern Territory (60.2%) and Western Australia (35.7%), predominantly affecting Aboriginal and Torres Strait Islander communities in remote areas. Both cutaneous (67.9%) and respiratory (31.7%) forms of the disease have been observed. While no deaths have been recorded in 2026, one fatality is currently under investigation. Public health measures, including enhanced surveillance, vaccination campaigns, contact tracing, and infection control, are crucial to managing this resurgence of a largely vaccine-preventable disease. ## Ebola Virus Disease in Central Africa: A Global Concern Ebola Virus Disease (EVD) is a severe, often fatal illness in humans caused by the Ebola virus. It is a viral hemorrhagic fever transmitted through direct contact with blood, body fluids, and tissues of infected animals or people, or surfaces contaminated with these fluids. The current outbreak in the **Democratic Republic of Congo (DRC)** and **Uganda** is particularly concerning as it involves the Bundibugyo virus, a strain for which there are currently no specific approved treatments or vaccines. Recognizing the gravity of the situation, the World Health Organization (WHO) declared this Ebola outbreak a Public Health Emergency of International Concern (PHEIC) on May 16, 2026. As of May 21-22, 2026, a total of 85 confirmed cases and ten deaths have been reported across both countries, including two confirmed imported cases and one death in Uganda. In the DRC, the outbreak is concentrated in Ituri, North Kivu, and South Kivu provinces. Challenges such as high population mobility, ongoing humanitarian crises, difficulties in contact tracing, and inadequate isolation facilities continue to complicate control efforts. Despite the seriousness, the WHO currently advises against imposing travel or trade restrictions. ## Murray Valley Encephalitis: An Australian Climate-Linked Risk Murray Valley Encephalitis (MVE) is a rare but potentially severe neurological disease caused by the Murray Valley Encephalitis virus, transmitted to humans by mosquitoes. Most people infected with MVE virus experience no symptoms or only mild flu-like illness. However, in severe cases, the virus can cause inflammation of the brain (encephalitis), leading to symptoms like severe headache, high fever, neck stiffness, confusion, seizures, coma, and even death or long-term neurological damage. In **Australia's Northern Territory**, MVE virus has recently been detected, raising public health concerns. Two confirmed cases in Alice Springs have tragically resulted in death, and the virus has also been found in mosquitoes in the greater Darwin area. The intense wet season has created ideal conditions for mosquito breeding, increasing the risk of transmission for this potentially life-threatening infection. Health authorities are conducting enhanced mosquito surveillance and control measures and urging healthcare professionals to consider MVE in patients presenting with compatible symptoms, particularly during the high-risk season from February to July. Personal protection against mosquito bites, such as using repellents and wearing long clothing, is highly recommended. In summary, these diverse health alerts underscore the continuous need for robust surveillance, rapid response mechanisms, community engagement, and regional and international cooperation to safeguard public health against both familiar and emerging infectious diseases. Individual actions, from vaccination to mosquito control, play a vital role in these collective efforts.