MADISON, Wis. -

Amber Grenfell said her family just can’t shake the sickness.

"There hasn't been more than one, maybe two days where we seem to be over the hump and then it just starts all over," Grenfell said.

Grenfell had to take her three-year-old daughter to the hospital just after Christmas. The toddler was treated over two days for dehydration. The doctors told Grenfell her vomiting was linked to the flu.

"It's definitely scary having a three-year-old hooked up to an IV in the hospital," Grenfell said. "And having a seven-month-old, we kind of had to quarantine them to different parts of the house to try and keep them separate."

The state Department of Health Services (DHS) reported 565 influenza-related hospitalizations since the beginning of October. Fifty of those cases happened in Dane County.

In addition, DHS statistics show about one in five of those hospitalized have been admitted to the intensive care unit (ICU), and nearly one in ten have required mechanical ventilation.

Saint Mary’s nurse epidemiologist Ellen Smith said the major strain hitting Wisconsin this year is the same H1N1 virus that caused the pandemic back in 2009. She said instead of the young children and elderly patients influenza tends to attack, this flu has the tendency to hit young and middle-aged adults. State data supports that observation.

"They feel that they're invincible, and oh, I've gotten sick before and this is nothing new. And it's really important that everybody to heed that warning," Smith said.

Unlike the situation Wisconsinites faced four years ago, Smith said we are better prepared for this strain of flu.

"The good news is it's a good match with the vaccine," Smith explained, "so if you've been immunized, you should have some protection against that. If you haven't been immunized, it's not too late to get a flu shot. It's never too late as long as the vaccine is available."

Smith expected the flu season to continue for at least a few more weeks, peaking sometime this month or next month. She added that those who have come down with severe cases of influenza are also more prone to other illnesses making their rounds this time of year.

"It's not unusual to see if somebody has influenza that they have pneumonia a couple weeks later or shortly thereafter as well. So you're just much more compromised and run down after a respiratory illness," Smith said.

Smith suggested not only getting a flu shot, but also doing what mom taught us when we were young. She said washing your hands, disinfecting your home, and covering coughs can go a long way to preventing the spread of the flu virus and other illnesses this time of year.