As H5N1 bird flu continues to spread wildly among California dairy herds and farmworkers, federal health officials on Thursday offered some relatively good news about Missouri: The wily avian influenza virus does not appear to have spread from the state's sole human case, which otherwise remains a mystery. On September 6, the Missouri Health department announced that a person with underlying health conditions tested positive for bird flu, and later testing indicated that it was an H5N1 strain related to the one currently circulating among US dairy cows.