Michigan officials on Monday said that Canada geese in the state had tested positive for a lethal strain of bird flu, bringing the worst outbreak of the disease in United States history. Three young geese collected in Sterling Heights, Mich., about 20 miles north of Detroit, were infected with the highly pathogenic H5N2 flu strain, according to the Michigan Department of Natural Resources. Nationwide, more than 46 million chickens and turkeys have been killed by bird flu or culled to prevent its spread. Michigan is the 21st state to confirm a case since late 2014 and the sixth to detect it only in wild or free-ranging bids, according to the department.