Nearly 58% of flu increase in Arizona found in children

The Arizona Department of Health Services reports compared to last year's flu season, the number of flu cases has increased by nearly 75% and about 58% of that increase is the B-strain, also known as the Influenza B, and is mainly found in children ages 18 and younger.

"We know that Influenza B impacts kiddos more and we usually see that in the second half of the influenza season," Dr. Cara Christ said.

The health department says this year, flu cases started popping up earlier and they are seeing a lot more of them -- approximately 8,600 cases have been reported this flu season so far.

"When we look at influenza, we see in Arizona a peek between January and March," Dr. Christ said. "This year, we've seen cases as early as October or November."

And there's a large number of flu cases that go undocumented.

"So the cases that we're reporting, we know are only the tip of the iceberg because they are the ones that have gone, had the flu tested and have been reported to the department," Dr. Christ said. "A lot of people don't go to the doctor for flu, so we know we're just seeing a small minority of cases." 

However, the department of health also says although flu cases have spiked, the number of flu shots has stayed the same.

IOWA CITY, IA - AUGUST 11: Marisa Grunder, 27 of Wilton, Iowa, is given a shot during trials of an H1N1 vaccine, developed by CSL of Australia, at University of Iowa Health Care, the University's medical center, on August 11, 2009 in Iowa City, Iowa.