Bird Flu More Widespread in Sewage Than Tests From Farms Show

A Michigan farmworker who tested positive for bird flu is just the second person to have been infected since an outbreak in US cattle appeared in March. Surveillance of sewage suggests the virus may be more widespread among dairy cows than reported, raising workers’ risk.

Academic and industry-run labs have been leading the way toward more nuanced and complete information about the H5N1 virus’s range by analyzing wastewater. They found bird flu in sewage samples collected before the virus had been identified in US cows. They’re seeing signs in cities that are far from infected cattle herds. And they’re already ...