Health officials are reporting that a unique type of swine flu has now been diagnosed in seven people in California and Texas, up from the two reported earlier this week.
As with the original two cases, the five new cases in the two states have all recovered, and testing indicates some mainstream antiviral medications work against the virus.
Only a few of the seven people were in contact with each other, and none were in contact with pigs, which is prompting a medical mystery.
US Centers for Disease Control and Prevention officials have announced that they are expanding their investigation.