Avian influenza outbreaks can have human health, economic, and conservation impacts; and monitoring and investigating outbreaks guides the implementation of biosecurity measures to reduce these impacts.

WildHealthNet facilitated the first detection of Highly Pathogenic Avian Influenza (HPAI H5N1) in free-ranging wild birds in Cambodia. In early 2021, government rangers and community members in South Eastern Cambodia detected a wild bird mass mortality event of over 2000 wild birds. With support from WildHealthNet, a multisectoral joint investigation was conducted by environment and animal health government agencies, conservation organizations, and local authorities to determine the cause of the mortality event. HPAI H5N1 was ultimately detected by the national laboratory and relevant stakeholders were notified, enabling them to notify local communities and implement mitigation strategies to prevent the expansion of the HPAI outbreak to humans and domestic poultry. This network of stakeholders is essential for efficient communication and coordinated response during an outbreak, particularly when outbreaks with economic and human health risks occur near international borders. Sequencing showed the virus to be closely related to those found in domestic poultry in neighboring Vietnam, suggesting the virus could have spilled over from domestic poultry.

Field investigation of an avian mass mortality event in Cambodia in 2021.  Photo: WCS Cambodia

Whilst the Cambodian investigation was taking place, WildHealthNet also supported AI investigations in Dong Thap province, southern Viet Nam, which borders south-eastern Cambodia. In collaboration with the Dong Thap Provincial Department of Animal Health, bird populations were surveyed during a joint investigation and HPAI H5N1 was detected in sick and dead free-ranging wild birds in Tram Chim National Park. Communication of these findings to local authorities in wildlife, agriculture and human health sectors supports coordinated mitigation efforts and targeting of additional surveillance in wild and domestic species.

Sample collection for Avian Influenza Virus (AIV) testing from a sick Asian openbill stork in Tram Chim National Park, Dong Thap province, Viet Nam. Photo: WCS Viet Nam