The ecology of highly pathogenic avian influenza virus

The natural reservoirs of avian influenza virus (AIV) are dabbling ducks of the Subfamily Anatinae, which typically carry low pathogenic (LP) AIV. However, over the past decade, the goose/Guangdong/1996 clade 2.3.4.4 lineage of H5 highly pathogenic (HP) AIV has become endemic in ducks nearly globally. Ducks are efficient carriers of the virus because they are highly susceptible to infection, the disease is mild or absent, and they can shed the virus for weeks. Also, the virus has been shown to survive in some habitats over six months, allowing for environmental transmission. As ducks migrate, they spread the clade 2.3.4.4 viruses to resident birds and other species, including mammals. Reported mammalian infections in wildlife with clade 2.3.4.4, H5 HPAIV have generally been fatal and "dead end" and don't transmit further among the new species. Many reported mammalian infections have occurred in predatory and scavenger species that were likely infected through ingestion of infected prey or carcasses. Notably, the virus was discovered in dairy cows in the US in March 2024 and appears to have become endemic in dairy herds in the US. Based on genetic analysis, the virus in cows appears to be a wild bird in origin and is a very rare event where sustained transmission in a new host has occurred. Finally, poultry, especially chickens and turkeys, generally do not serve as long-term reservoirs because the virus is fatal and frequently controlled by stamping out.

Keywords: HPAI, Ecology, Clade 2.3.4.4, Mammals.

     

Citation. Spackman, E. 2024. The ecology of highly pathogenic avian influenza virus. Second International Avian Influenza and One Health Emerging Issues Summit 30th Sep – 3rd Oct 2024, The University of Arkansas, Fayetteville, Arkansas, USA. GMPC TOP. 4 (2). pp.35. https://doi.org/10.51585/gtop.2024.2.0037

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