Questions in China on how H7N9 flu strain killed 2

A vendor waits for customers near chicken cages at a market in Fuyang city, in central China's Anhui province, Sunday, March 31, 2013. Two Shanghai men have died from a lesser-known type of bird flu in the first known human deaths from the strain, and Chinese authorities said Sunday that it wasn't clear how they were infected, but that there was no evidence of human-to-human transmission. A third person, a woman in the nearby province of Anhui, also contracted the H7N9 strain of bird flu and was in critical condition, China's National Health and Family Planning Commission said in a report on its website. (AP Photo) CHINA OUTBEIJING (AP) — Health officials say they still don't understand how a lesser-known bird flu virus was able to kill two men and seriously sicken a woman in China, but that it's unlikely that it can spread easily among humans.