The CDC has picked five lab partners to develop a test for avian influenza A(H5N1) — bird flu — including ARUP Laboratories in Salt Lake City.

Health officials on Thursday said they don’t know how a Missouri person caught bird flu but believe it may be a rare instance of a “one-off” standalone illness.

As bird flu continues to spread through dairy cow herds and poultry flocks, the Missouri case has raised the possibility of human-to-human transmission of bird flu. But officials stressed Thursday there is no evidence of other people being infected and the risk to the general public remains low.