Ten states are now reporting widespread seasonal activity of flu - and the Centers for Disease Control have said that number is only set to rise.
Activity has been reported in Alabama, Alaska, Kansas, Louisiana, Massachusetts, New York, Pennsylvania, Texas, Virginia and Wyoming, according to the CDC's weekly flu advisory report, covering the week ending December 21 - up from only four the week before.
Worryingly the strain of virus most prevalent is the H1N1 - better known as swine flu - which killed tens of thousands of people in a global outbreak in 2009.
On the rise: Ten states have widespread flu activity as of the week ending December 21 - and that is only set to rise
The CDC's definition of widespread is that 50 percent of a state's counties are reporting outbreaks of flu - but does not address the severity of this years particular strain of flu.
So far, 'it's a typical influenza season, if I can use that word,' said Dr. Michael Jhung, a medical officer in the CDC's flu division to CNN.
However, the emergence of swine-flu being the most prevalent type of the virus seen this year has raised eybrows.
'It's the same virus that we saw in 2009 that caused the pandemic,' Jhung said.
On the rise: This map from the CDC shows current levels of activity for flu - revealing that the Southern States are the hardest hit
But, Jhung was keen to point out that now swine flu is so common it is part of this years flu vaccine and only four children have been reported to have died from flu this season.
The hardest hit region of the nation is the south, while the southwest seems to have escaped almost entirely from this years flu outbreak.
Last year alone, 381,000 people were hospitalized with flue and 169 children died - Jhung told CNN that was a particualrly severe outbreak.
The CDC estimates that flu vaccination prevented 6.6 million illnesses last year, 3.2 million doctor visits and at least 79,000 hospitalizations.
Read more: http://www.dailymail.co.uk/news/article-2531026/Swine-flu-sweeps-nation-takes-hold-ten-states-hitting-south-hardest.html#ixzz2oyWdc5bh
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