Industrial poultry production and reemerging avian flu

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By Emily Gilbert

According to the United Nations Food and Agriculture Organization (FAO), there are alarming signs that a new mutant strain of the avian flu, or H5N1 Highly Pathogenic Avian Influenza, is spreading in Asia and beyond. H5N1 Highly Pathogenic Avian Influenza (HPAI) is a potentially devastating virus, associated with a high mortality rate and high economic losses.   HPAI viruses can jump species barriers and infect humans, becoming a potential source of a future pandemic.

A chicken being vaccinated against the H5N1 virus (Photo credit: CRDF)

Although wild birds and small-scale poultry production have been blamed for the spread of avian flu, recent research conducted by Tour du Valat, a Mediterranean wetland conservation research center, has found that when the avian flu virus infects poultry, not wild bird species, it mutates into the highly pathogenic strains of the flu .  These findings are supported by separate research on outbreaks in Nigeria and Thailand, which found that human agricultural activity and industrial poultry production, or factory farming, are major sources of the global spread of the avian flu.

After a 2002 bird flu outbreak in Chile, a study published in Emerging Infectious Diseases  identified poultry as the primary species in which the more highly pathogenic strains evolved.  A separate study produced in part by the Joint Influenza Research Centre at Hong Kong University found that, “transmission within poultry is the major mechanism for sustaining H5N1 virus endemicity in this region.”  Interestingly, in the Southeast Asian countries where most of the bird flu outbreaks are concentrated, including Thailand, Laos, and Vietnam, poultry production grew eightfold over the last three decades, from around 300,000 metric tonnes of meat produced in 1971 to 2,440,000 metric tonnes in 2001. In China where the H5N1 virus has also spread, poultry production tripled during the 1990s, with 15 billion ducks, geese and chickens raised in 2004.