US health officials have reported that the strain of bird flu detected in a California child is similar to the strain spreading through livestock. However, the patient had no known exposure to infected animals.

Infectious disease experts have called for expanded testing for H5N1 bird flu in milk since it began spreading among dairy cows in the United States this year. They argue that the virus can’t be contained until farms,

Investigators trying to determine how a child in California might have contracted bird flu are continuing to learn more details about the case.