DES MOINES, Iowa (AP) — Wild birds are believed to be behind the first major widespread outbreak of bird flu in the United States, with the virus confirmed in the animals in 10 states. The number of birds infected climbed to more than 9 million Monday with more reported cases in Iowa. Here are some questions and answers about how wild birds remain healthy even when carrying the virus and spread it to backyard and commercial flocks of chickens and turkeys.

Source: An explanation of wild birds’ role in avian flu outbreak – US News