Scientists are tracking a deadly bird flu outbreak that has infected wild birds in more than 30 states. Purging the nation's poultry supply may not be enough to keep the virus from sticking around.

Nearly 23 million birds have died as a highly pathogenic bird flu virus tears its way through farms and chicken yards. It has spread to at least 24 states in less than two months.

Early last week, a flock of chickens at a Northwest Georgia farm tested positive for bird flu. It’s the first confirmed contamination of commercial...