A worker arranges containers of chickens at a wholesale market on Thursday, April 4, 2013, in Shanghai, China. In a worrisome sign, a bird flu in China appears to have mutated so that it can spread to other animals, raising the potential for a bigger threat to people, scientists said Wednesday. (AP Photo)
Four people in China have died so far from a new strain of bird flu.
Eleven total people are infected with the H7N9 virus, according to Chinese state TV.
The first three cases were in eastern China on Sunday.
Chinese authorities are still looking for the source of the virus.