CHICAGO— A third U.S. dairy worker tested positive for bird flu after exposure to infected cows, and was the first to suffer respiratory symptoms, U.
S. officials said early this month in the latest expansion of the outbreak. Bird flu has been found in dairy cattle in nine states.
This second case in a Michigan dairy worker was found through increased testing of people and cows in the state following the April 1 identification of a case in a Texas farm worker. Here’s what you need to know about the outbreak. Health officials say the risk to public health remains low.
But the spread of avian flu among dairy cattle reflects an expansion of the range of mammals that can be sickened by the virus that typically infects birds, and influenza experts said finding bird flu in humans was worrisome. Scientists are on alert for changes in H5N1 that could signal the virus is adapting to spread easily among humans. The virus has caused serious or fatal infections among people in close contact with wild birds or poultry and has long been on the list of viruses with pandemic potential.
Any expansion to a new mammal species is concerning. The infections in cattle are from the same subtype of bird flu that has been infecting wild birds and poultry flocks globally for more than two years, also killing several mammal species that likely contracted the virus from consuming sick or dead birds. The full extent remains unknown, but it may be in more herds than documented.
The U.S. Food and Drug A.