When You're in the Market For Bird Flu

 
Based on USDA Data - Graph created with Gemini

#19,058

Since the arrival of H5N1 in late 2021, the USDA has reported 64 outbreaks in live bird markets (LBMs) across 6 states (NY, NJ, PA, FL, VA, CA), with 10 outbreaks reported over the past 60 days.

While outbreaks in live bird markets continue to be reported to the USDA, they appear to be getting far less press coverage than they were a year ago. 

The link between live bird markets and the spread (and potential reassortment of) avian flu strains has been long established. LBMs typically bring together birds of varying species (chickens, ducks, geese, quail, and others) - often imported from different farms - which are housed in cramped quarters. 

A dozen years ago, in CDC: Risk Factors Involved With H7N9 Infection we looked at a case-control study conducted by an international group of scientists, including researchers from both the Chinese and the US CDC that concluded.

Exposures to poultry in markets were associated with A(H7N9) virus infection, even without poultry contact. China should consider permanently closing live poultry markets or aggressively pursuing control measures to prevent spread of this emerging pathogen. 

In 2016's Interventions in live poultry markets for the control of avian influenza: A systematic review Vittoria Offeddu , Benjamin J. Cowling, and J.S. Malik Peiris laid out the risks of avian influenza from live bird markets, reviewed some of the possible interventions, and concluded: 

Highlights

• Avian influenza viruses (AIVs) can infect humans. Bird-to-human transmission is particularly intense in live poultry markets.
• Periodic rest days, overnight depopulation or sale bans of certain species significantly reduce AIV-circulation in the markets.
• Market closure would lastingly reduce the risk of animal and human infection.

Admittedly, practices and hygienic standards vary greatly between countries, but last summer in J. Virology: Zoonotic Disease Risk at Traditional Food Markets (Minireview), we looked a review that cautioned that `. . . their sustainability and safety depend on integrating evidence-based strategies to mitigate zoonotic disease risks.'

While less common here than in Asia and the Middle East, the United States has hundreds of live bird markets, clustered primarily in the mid-Atlantic region (see Live Bird Markets of the Northeastern United States by Jarra F Jagne, DVM et al.)

Live bird markets serve mainly ethnic immigrant populations in large urban centers of Northeastern states. The markets are important in the epidemiology of avian influenza viruses (AIV) especially H5 and H7 strains that have zoonotic potential and an effect on trade with United States trading partners.

Until four years ago, HPAI H5 was not endemic in North America, which greatly reduced (but didn't completely eliminate) the risks of avian flu transmission in U.S.  live bird markets (see 2016's H5 Avian Flu Reported In NE U.S. LBMs (Live Bird Markets) - UPDATED).

Over the past few years the threat from H5N1 has grown markedly in the Western Hemisphere. So far, the strains of HPAI H5 in the United States have been generally milder in humans than those seen in Asia and the Middle East, but serious illnesses and deaths have occurred, and further increases in virulence are possible. 

 

Practices (like fur farming, drinking raw milk, letting your cat run free outdoors, or working at or visiting an LBM) - that were once presumably less dangerous  - are arguably more dangerous now. 

But we resist adapting to - or preparing for - new threats like avian flu because of the `Normalcy bias', the belief that tomorrow will be more-or-less like yesterday. We cling to the notion that all future changes will be small, incremental, and manageable. 

While that may bring comfort, and a sense of stability, it also brings risk. 

Whether HPAI H5 has the `right stuff' to spark a pandemic is unknown. But somewhere out there, the next pandemic virus is honing its skills.  And our laissez faire attitude towards pandemic prevention and preparedness will eventually prove costly.