Active Public Health Outbreaks in the WHO Western Pacific Region
Date: November 30, 2025
Region Scope: Western Pacific (37 countries and areas, including China, Japan, Philippines, Vietnam, Australia, and Pacific Island nations).
The Western Pacific Region is currently navigating a complex "poly-epidemic" landscape. While the acute phase of the COVID-19 pandemic has passed, the region is grappling with a significant resurgence of vaccine-preventable diseases, persistent vector-borne threats intensified by climate patterns, and sporadic but lethal zoonotic spillover events. The data below synthesizes reports from the WHO Western Pacific Regional Office (WPRO), the US CDC, and national ministries of health as of late 2025.
1. The Resurgence of Vaccine-Preventable Diseases
Measles & Pertussis: The most critical public health failure in the region for the 2024–2025 period is the backsliding of routine immunization. Measles cases have surged by over 743% between 2022 and late 2024/2025.
- Philippines: Continues to battle a severe Pertussis (Whooping Cough) outbreak. By late 2024, cases had risen 34-fold compared to the previous year.
- Vietnam (Hanoi/HCMC): A confirmed measles outbreak is active as of early 2025, with over 600 cases recorded in Hanoi alone, affecting all districts.
- Australia: Multiple imported measles cases have triggered local alerts in NSW, Victoria, and Queensland, threatening community transmission pockets.
| Country | Disease Focus | Status (Late 2025) | Trend |
|---|---|---|---|
| Philippines | Pertussis | Active Outbreak | ? 3400% vs 2023 |
| Vietnam | Measles | Resurgence | ? Widespread in Cities |
| Cambodia | Measles | Cluster Outbreaks | ? Post-Elimination Re-entry |
2. Vector-Borne Threats: Dengue & Japanese Encephalitis
Dengue Fever: The Pacific Islands are currently under a "Blue Alert" status for Dengue (DENV-1 and DENV-2 serotypes). Outbreaks are confirmed in French Polynesia, Samoa, Tokelau, and Kiribati. In Vietnam and the Philippines, dengue remains hyper-endemic with seasonal spikes.
Japanese Encephalitis (JEV): Once confined to Asia, JEV is now firmly established in Australia. The 2024–2025 season has seen detections in feral pigs and human cases across Victoria, NSW, and Queensland, signaling a permanent shift in the virus's geographic range.
3. Zoonotic & Emerging Pathogens
Avian Influenza (H5N1)
Cambodia & Vietnam: Sporadic human cases continue to be reported, often with high case fatality rates (over 50%). Recent cases in Cambodia (Kratie province) involved pediatric fatalities linked to direct poultry contact.
Contrast: While human cases remain "sporadic" and inefficient in transmission, the virus is widespread in poultry markets. Surveillance often misses mild cases, suggesting the "tip of the iceberg" phenomenon.
Mpox (Clade Ib & IIb)
The region remains on high alert following the global PHEIC declaration. Australia is managing an ongoing outbreak of Clade IIb. However, surveillance systems in China, Thailand, and Singapore are actively screening for the more severe Clade Ib variant, which has been detected in travel-related cases in the broader Asia region.
Leptospirosis
Following severe typhoon seasons in mid-to-late 2025, the Philippines (Metro Manila) and Vietnam have reported surges in Leptospirosis. Hospitals in Manila activated "surge capacity" plans in August 2025 due to the influx of cases from floodwater exposure.
4. Respiratory & Seasonal Trends (COVID-19 & HFMD)
Hand, Foot, and Mouth Disease (HFMD): Vietnam is experiencing a significant surge. In Ho Chi Minh City, cases in 2024/2025 rose by 49% compared to the previous period. The circulation of Enterovirus 71 (EV71) is of particular concern due to its link to severe neurological complications in children.
COVID-19: A new variant, NB.1.8.1, has driven a rise in test positivity (reaching 11%) across the Western Pacific in mid-to-late 2025.
Viewpoint Contrast: The WHO maintains the global public health risk is "low" due to vaccine efficacy. However, local sentinel data indicates high community transmission, suggesting that "living with COVID" continues to exert pressure on healthcare systems during seasonal peaks, distinct from the "post-pandemic" narrative of disappearance.