Are backyard hens resistant to H5N2?

H5N2 avian flu is getting more curious as time goes by. It was initially spread by migrating waterfowl, but recently producers have seen it spread from flock to flock, even in highly secure production facilities. Midwest producers have lost more than 21 million birds to the flu. Yet scientists at the U.S. Department of Agriculture, the Centers for Disease Control and Prevention and other federal agencies are puzzled by the H5N2 virus' spread, even with heightened biosecurity measures, and the apparent lack of deaths in largely unprotected backyard flocks.

Dr. T.J. Myers, the USDA associate deputy administrator of veterinary services, recently told the Associated Press that no one is sure why there hasn't been a surge in infections of backyard flocks. The USDA has identified only 12 cases of home flock infections in seven states since the outbreak started five months ago.

Cases might not be reported, French said. Commercial operations have a financial incentive to immediately report illnesses because the government pays them for each live bird that must be destroyed. We didn’t know the taxpayers were paying for 21 million dead chickens, but we’re not surprised.

French said there might be another reason, too. Outdoor chickens could have been exposed over time to low pathogenic versions of bird flu and have developed stronger immunity. We wonder whether it might not be a good idea to let commercial flocks get a little immunity, too, along with some sunshine and green grass.