The worst animal virus outbreak in U.S. history has killed 48 million birds, yet no humans have been infected. Still, a medical officer in the Centers for Disease Control's (CDC) Influenza Division says the department is "concerned" that the bird flu virus may mutate.
"These are the first of these types of viruses that we're seeing," Dr. Michael Jhung tells CNBC in an interview with "On The Money."
He added: "Because [the viruses are] new, we're a little concerned because we don't know how dangerous they could be."
Although there hasn't been any new bird flu cases since mid-June, USDA officials are preparing for a possible return of the virus this fall.
Today, the CDC considers the risk of infection to the general public as low. However, the agency is advising people to stay away from sick or dying birds. If it is necessary, Jhung said, wear coveralls, face masks and eye protection.
Cooler weather and wild bird migration could bring a recurrence of the disease, according to experts. The two states hardest hit by the outbreak were Iowa and its egg-laying chickens, and Minnesota's turkey population.