South Dakota health officials are urging people in the state to get a flu shot after a recent increase in the number of people infected with the virus.
The virus has already proved deadly in the state and the number of people diagnosed with the flu has increased dramatically in the past few weeks.
It's that time of year: when the weather gets cooler and the battle against influenza heats up.
"I've noticed people getting sick like they do every winter," Anastasia O'Hara said.
O'Hara protected herself from the flu this year by getting a flu shot. But not everyone did and flu season is striking even sooner this year.
"I think the earliest since 2009, since we had the H1N1 pandemic," Sanford family practice physician Dr. Wallace Fritz said.
A flu shot, Dr. Fritz says, is the best way to protect yourself from the potentially-deadly virus.
"All of the cases I've seen, personally, have been people who have not been vaccinated. People who have been vaccinated tend to have pretty good protection with this influenza," Dr. Fritz said.
If you do think you may have influenza, Dr. Fritz says you should see a doctor right away. Some of the symptoms include being tired, achy, having a high fever and a cough.
"A lot of times people with influenza come in and say, 'At 6:30 last night is when it started.' They can name a time. It's an abrupt onset of fever, chills and body aches," Fritz said.
If you do come down with influenza, Fritz urges you to stay home and avoid spreading the virus.
"We're infectious up to 24 hours before we're even having any symptoms, but certainly until you're feeling better and the fever has subsided," Fritz said.
The good news is it's not too late to get a flu shot.
"It's still available and it's still not too late. I would recommend that people who haven't been vaccinated get vaccinated," Fritz said.
The most recent report from the South Dakota Department of Health shows 335 confirmed cases of the flu in the state. At this point last year there were only five confirmed cases.