Bird Flu (H5N1) Outbreaks: Timeline and Global Impact

H5N1 Avian Influenza: Major Outbreaks

2003–Present: Panzootic Wave

• Origin: Guangdong, China (1996 precursor); widespread from 2003.
• Spread to >60 countries across Asia, Europe, Africa, Middle East.
• Hundreds of millions of poultry died or culled.

Human Infections (as of 2023)

• ~870 confirmed cases (WHO), ~53% fatality.
• Mostly direct poultry contact; limited, non-sustained human-to-human transmission.
• Clades: 2.3.4.4b (current dominant) spreads widely in wild birds, causing unprecedented poultry outbreaks 2021–2023.

Recent Developments (2020–2023)

• Massive wild bird mortality (seabirds, raptors).
• Spillover to mammals: foxes, seals, mink farms (Spain, Finland), sea lions (Peru, Chile).
• Few human cases from clade 2.3.4.4b (mild/asymptomatic mostly).
• Pandemic concern: Mammalian adaptation mutations monitored.

Control Measures

• Surveillance, biosecurity, vaccination (poultry, in some countries), culling, movement restrictions.
• One Health approach: human, animal, environmental sectors.