Abstract
Highly pathogenic avian influenza (HPAI) H5N1 was first detected in Vietnam in 2001 in geese from live bird markets (LBMs) [1], with subsequent outbreaks reported in Cambodia, Thailand, and Laos. HPAI H5 clades 2.3.2.1c and 2.3.4.4 have predominated in Vietnam since 2014 [2], and clade 2.3.2.1c is endemic in Laos and Cambodia [3]. Cross-border trade of domestic birds, LBMs, and free-grazing duck systems contribute to the virus’s persistence in the region, threatening public and animal health, livelihoods, and biodiversity. In 2021, Cambodia’s wildlife health surveillance network investigated several mass mortality events in wild waterbird colonies throughout wetlands which have duck farms located adjacent. In Vietnam, concurrent wild bird mortalities were detected during investigations in protected areas near the Cambodia border. Phylogenetic analyses determined the outbreaks in both countries to be H5N1 clade 2.3.2.1c and suggest these outbreaks may be of poultry origin. From 2021 - 2024, annual mass die-offs of wild waterbirds during nesting season due to H5N1, primarily involving Asian open-bill storks (Anastomus oscitans), have been detected across five Cambodian wetlands. Meanwhile, outbreaks of H5N1 have been recorded in nearby poultry farms [4], along with 13 human spillover events since early 2023, with multiple of these confirmed human infections proving fatal [5]. Significant knowledge gaps remain regarding the disease ecology at the domestic-wild bird interface in Southeast Asia and within/between wild bird colonies. Enhanced surveillance and spillover risk reduction at these interfaces are essential to prevent further impacts on Southeast Asia’s unique waterbird species and global public health.
Co-Author(s)
Emily Denstedt[1*], Alice Latinne[2*], Alice Porco[3*], Sokha Chea[3], Sreyem Sours[3], Vor Sina[3], Santi Choun[3], Sothyra Tum[4], Sorn San[5], Hong Chamnan[6], Bunna Um[7], Erik Karlsson[8], Jurre Siegers[8], Nguyen Thi Thanh Nga[9], Pham Thi Bich Ngoc[9], Lam Kim Hai[10], Diego Montecino-Latorre[11], Amanda E. Fine[11]
1 Wildlife Conservation Society, Greater Mekong and South Asia Regional Programs
2 Wildlife Conservation Society, Southeast Asia-Pacific Regional Program
3 Wildlife Conservation Society, Cambodia Country Program, Phnom Penh, Cambodia
4 National Animal Health and Production Research Institute, General Directorate of Animal Health and Production, Phnom Penh, Cambodia
5 General Directorate of Animal Health and Production, Phnom Penh, Cambodia
6 Department of Freshwater Wetlands Conservation, Ministry of Environment, Phnom Penh, Cambodia
7 Defense Threat Reduction Agency-Biological Threat Reduction Program, United States Embassy, Phnom Penh, Cambodia
8 Institut Pasteur du Cambodge, Phnom Penh, Cambodia
9 Wildlife Conservation Society, Vietnam Country Program, Hanoi, Viet Nam
10 Pet5h Veterinary hospital, Hanoi, Viet Nam
11 Wildlife Conservation Society, Health Program, Bronx, NY, USA
*Equal contributions to this work
Abstract Category
Notable outbreaks, field and molecular epidemiology, and surveillance in wild birds