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Testing by the U.S. Food and Drug Administration from April found that 20% of retail milk samples showed fragments of the H5N1 virus. That testing included 297 samples from retailers in 17 states coming from processing locations across 38 states. Still, only nine states so far have confirmed bird flu infections among their cow herds. Public health experts worry states just aren't doing enough surveillance to capture the real number of infections.

217 Today: Bird flu continues to spread. Scientists worry states aren’t testing enough to know the extent of it

The 217 Today Podcast