Four poultry workers in Colorado have been diagnosed with bird flu, health officials confirmed Sunday. The new cases bring the U.S. total to nine since the first human case of the current outbreak was detected in 2022, also in a Colorado poultry worker. Eight of the nine were reported this year. Their illnesses were relatively mild — reddened and irritated eyes and common respiratory infection symptoms like fever, chills, coughing, sore throat and runny nose.