Avian influenza overview June - September 2022

Area of Science:

• Veterinary Virology
• Epidemiology
• One Health

Background:

• The 2021-2022 season marked the most extensive highly pathogenic avian influenza (HPAI) epidemic in Europe to date.
• Significant HPAI A(H5N1) virus outbreaks occurred in poultry, captive birds, and wild birds across 37 European countries, with unprecedented geographical spread.
• Massive mortality events in seabird populations were observed, contributing to a high number of HPAI detections in wild birds.

Purpose of the Study:

• To analyze the epidemiological characteristics of the 2021-2022 HPAI epidemic in Europe.
• To assess the impact on different bird populations and geographical regions.
• To inform the development of sustainable HPAI mitigation and surveillance strategies.

Main Methods:

• Analysis of HPAI outbreak data from poultry, captive birds, and wild birds across European countries.
• Monitoring of HPAI virus detections and geographical distribution.
• Genotypic analysis of circulating HPAI viruses (clade 2.3.4.4b).

Main Results:

• A total of 2,467 outbreaks in poultry, 187 in captive birds, and 3,573 detections in wild birds were reported.
• The epidemic exhibited unprecedented geographical extent, from Svalbard to South Portugal and Ukraine.
• Increased HPAI outbreaks in poultry were observed compared to 2021, particularly along the Atlantic coast.
• HPAI A(H5) viruses showed genetic markers for mammalian adaptation, with detections in wild mammals.
• Limited human infections (A(H5N6), A(H9N2), A(H10N3)) reported in China, with low risk to the general EU/EEA population.

Conclusions:

• The 2021-2022 HPAI epidemic necessitates revised and sustainable mitigation strategies, including biosecurity and early detection surveillance.
• The adaptation of HPAI viruses to mammals poses a potential emerging risk.
• Continued vigilance and international collaboration are crucial for managing HPAI.