Avian Influenza (Bird Flu) Pandemic Wreaks Havoc on Poultry and Wild Bird Populations

Strategic Insights -

New research on the highly pathogenic avian influenza (HPAI) virus has shed light on the devastating impact of the recent panzootic on seabird populations worldwide. The study, published in the Journal of Animal Ecology, estimated that the reproduction number of HPAI in wild populations was 3.7 in 2022 and 3.2 in 2023, with a significant drop in mortality rates from 0.26 to 0.14 over the same period. The research suggests that direct bird-to-bird transmission is the primary driver of infection within colonies, with environmental transmission playing a negligible role.

Key Takeaways:

  • Research indicates that the HPAI virus has led to the culling of massive amounts of poultry and the mortality of countless wild birds, with a significant impact on seabird populations globally.
  • The reproduction number of HPAI in wild populations was estimated to be 3.7 in 2022 and 3.2 in 2023, suggesting a potential decline in the virus's contagiousness.
  • Mortality rates for infected birds dropped from 0.26 in 2022 to 0.14 in 2023, indicating a possible reduction in the virus's virulence.
  • The study suggests that direct bird-to-bird transmission is the primary driver of infection within colonies, while environmental transmission plays a negligible role.
  • Daily carcass removal may have kept environmental transmission at bay, and increased immunity or a change in the strain of HPAI may have contributed to the drop in mortality rates.

Statistics:

  • 3.7: estimated reproduction number of HPAI in wild populations in 2022
  • 3.2: estimated reproduction number of HPAI in wild populations in 2023
  • 0.26: estimated mortality rate for infected birds in 2022
  • 0.14: estimated mortality rate for infected birds in 2023
  • 2021: year the recent panzootic began
  • 2022: year daily carcass removal began
  • 2023: year the study estimated the reproduction number and mortality rates

Sources:

  • NewsRx LLC (2025, October 21). Data on Avian Influenza (Bird Flu) Discussed by Researchers at Institute of Avian Research (Estimating epidemiological parameters of highly pathogenic avian influenza in common terns using exact Bayesian inference). TB & Outbreaks Week, 562.
  • Institute of Avian Research (2025). Estimating epidemiological parameters of highly pathogenic avian influenza in common terns using exact Bayesian inference. Journal of Animal Ecology.
  • Wiley (publisher). Journal of Animal Ecology.