Cats in two separate households died in May after developing severe illnesses that were confirmed as the Type A H5N1 bird virus found in U.S. dairy herds, investigators reported. Both were indoor-only cats that had no exposure to infected cattle or birds and didn’t consume raw milk.

Around five house cats in total have now died in the metro area since Christmas due to the spreading influenza. In all but one, raw pet food was the culprit.

But the study, whose publication was delayed by a pause in public communications by the agency, leaves key questions unanswered.