A flu outbreak is making its way around Arizona and hospitals say their emergency waiting rooms are packed.

The emergency room staff at Scottsdale Healthcare Osborn hospital usually sees 100 to 140 patients a day without any wait.

On Tuesday, they saw more than 200 patients and some patients had to wait four hours.

At Banner Desert Medical Center in Mesa, people with sniffles in the emergency room waited up to 10 hours while doctors and nurses tended to heart attack or other more serious patients.

"We have been slammed," said Banner spokeswoman Nancy Neff. "But obviously, we've been doing our best to get people through as quickly as possible."

Cases of influenza are on the rise.

State health officials counted 388 reports of flu in Arizona last week — 48 percent of all the cases reported so far this season.

Cold weather that passed through Arizona prompted the spike, health officials say. They also say visitors seeking refuge from snow country or staying with family may have brought in viruses.

Cases of strep throat, croup, common colds and bronchitis also are showing up, lengthening the line of patients waiting for care.

Like influenza, strep and other respiratory illnesses are fairly common in the winter.

But doctors say it's especially problematic for asthma patients at this time, when the Phoenix metropolitan area is under advisory for high pollution.

People suffering from asthma and other chronic ailments are more susceptible to influenza and other illnesses.

And although the flu season is in full swing, experts say it isn't too late for people to get a flu shot.