Influenza is spreading rapidly in Wyoming.
Wyoming Department of Health officials don't typically release numbers of flu cases in the middle of flu season but say cases have been increasing since early December.
Department spokeswoman Kim Deti says the dominant, B-strain virus is unusual for this time of year.
Flu deaths and hospitalizations nationwide are low because the strain affects children and younger adults more than the elderly.
The U.S. Centers for Disease Control rates Wyoming flu activity as moderate.
The agency currently rates most of the U.S. at the highest severity level for flu.