Two more bird flu cases reported in Colorado, but elsewhere a study finds no asymptomatic infections

U.S. health officials have announced two more bird flu cases among farmworkers. But here’s some good news: A new study in Michigan suggests the virus is not causing asymptomatic infections in people. Last month, the Michigan Department of Health and Human Services launched a study of workers who were around cows sickened by the bird flu. The researchers drew blood from 35 people. Meanwhile, two more infections tied to a Colorado poultry farm were reported, bringing the total to six. It’s the largest outbreak of human bird flu infections in U.S. history.