What is avian flu and how does it spread?

The particular strain of avian influenza that has everyone so concerned is called H5N1.  This strain of influenza was first detected in 1959 among domestic chickens in Scotland.  For reasons that may never be known, the virus broke out in 1996 at a goose farm in China’s southeastern Guangdong province. The virus reappeared in Asia in mid-2003 and has since been detected in farmed poultry or wild birds in about 50 countries in Asia, Europe, Africa and the Middle East, according to the World Health Organization (WHO). About 200 human cases – half of them fatal – have been reported in nine countries: Azerbaijan, Cambodia, China, Egypt, Indonesia, Iraq, Thailand, Turkey and Vietnam (which has had about 90).

Scientists have little idea precisely how the virus mutated from its naturally occurring, generally non-fatal form found in wild migratory birds, to an almost always fatal virus that has killed or led to the preemptive destruction of more than 200 million farm-raised chickens, geese, ducks and other birds since it emerged in southern China in 1996. The general theory is that at some unknown point in history, farmed birds became infected with the naturally occurring strain by coming in contact with infected wild birds, or by swimming in water or walking through dirt containing bodily fluids from infected wild birds. Once it reached concentrated, industrialized operations, the virus is believed to have mutated into its deadly form. For reasons that remain poorly understood, the deadly strain has been passed back to wild birds.

Are birds kept inside buildings safer than free-range poultry outside?

While many backyard flocks have indeed been infected, many huge factory-scale poultry farms have also been struck with the virus. And it is within these large operations – where up to hundreds of thousands of birds breathing, urinating and defecating in close quarters give viruses limitless opportunities to mutate – that scientists suspect the virus morphed from relative harmlessness to its current destructive form.

Yet, while international health organizations have called for a harsh crackdown on family-based farms, no such measures are being taken against industrial-scale operations. 
 

Can people get avian flu from eating chicken or eggs?

Most human cases have occurred in rural areas with small backyard flocks – when people directly handled or slaughtered infected birds, touched objects smeared with bodily fluids from infected birds, or swam in contaminated water. In its current form, H5N1 has rarely spread from one person to another.

No one is known to have been infected by eating undercooked poultry.  But if the virus is present in a bird that ends up in the food system, thorough cooking will kill it.  The USDA recommends that poultry be cooked to an internal temperature of 165° F (determined with a meat thermometer) and uncooked poultry should be kept separate from other foods and serving dishes.  Proper handling and cooking of poultry (see this USDA fact sheet) is an important step whenever you are preparing meat or poultry, to protect yourself from salmonella and other food borne illnesses.