A mixture of some of the aspects we love about the holidays — close contact with loved ones, special holiday gatherings and shopping amid a sea of strangers — likely contributed to a spike in flu cases in Butler County.

It is a flu season that experts say likely is to prove significant.

“There's been an explosion in number of patients coming in with the flu and flu-related complications,” said Dr. David Rottinghaus, medical director of the emergency department at Butler Memorial Hospital.

The emergency department, which generally treats about 130 people a day, has seen as many as 175 or 180 patients within a given 24 hours. At the same time, urgent care centers such as FastER Care and MedExpress are reporting 30 percent or 40 percent more patients a day.

Rottinghaus said some of the patient increase is due to expected holiday pitfalls. People don't watch their diets or bedtimes or when they are over enjoying or stressing holiday events. So many serious health concerns, like heart problems or strokes, manifest at this time of the year.

But this year's flu season, and the complications that can make the virus serious, are increasing.

Already the flu season has earned the state Department of Health “widespread” classification, which is defined as “outbreaks of influenza or increases in influenza cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.”

As of Dec. 27, the state confirmed 10,017 cases of flu statewide and 442 cases in the county. Comparatively, in the 2013-14 season, which ran October through May, the state confirmed 28,202 cases and the county confirmed 678 cases.

“This is turning out to be a big flu season,” said Rottinghaus, stressing that many flu cases are never reported to the state.

That is because some people never seek treatment. Others might see a doctor, but due to circumstances they are diagnosed without tests that would trigger reporting.

“That number (of cases confirmed by the state) is a good indicator of how widespread it is, but really it's only the tip of the iceberg,” said Dr. Amesh Adalja, infections disease physician at UPMC.

Wes Culp, deputy press secretary at the state Department of Health, said the department estimates that each year from 5 percent to 20 percent — 600,000 to 2.4 million Pennsylvanians — get the flu, resulting in 120 to 2,000 deaths.

“More tests will be positive as we head deeper into flu season,” said Adalja, who noted that flu season peaks in February.

There's a number of reasons that this year's flu season is getting an exceptional start, experts say.

To begin with, the vaccine that was distributed appears not to cover some of the more predominantly circulating flu strains, according to many experts including the Centers for Disease Control and Prevention's Internet site.

“It's a stroke of luck to cover all the strains in one vaccine,” Rottinghaus said. “But this is a year where strains that are circulating and making people sick just are not in the vaccine.”

Additionally, Rottinghaus said the flu started to spread at the end of December when school was still in session and children were in close contact to each other. Then, people attended public holiday gatherings, shopped in crowds and met in family functions, which further spread the virus.

“It hit at just the right time. Malls and shopping centers were full and school just coming to the end,” Rottinghaus said. “It really spread it around and now it's settling into families.”

In addition to being widespread, the virus is expected to be especially daunting this year.

The predominant strain, the H3N2 variety, “tends to produce more severe flu than others so we would expect to see more severe and even more fatalities,” Adalja said. “Especially because the strain is mismatched (to the vaccine).”

Still, for the most part, flu sufferers can treat at home and recover.

“If you are a young, healthy person no medical problems, like asthma, you still will feel terrible,” Rottinghaus said. “Hydrate, bring down the fever and you will be OK.”

Rottinghaus said many people can treat flu symptoms with rest, liquids and over-the-counter medications.

“Read the labels carefully or ask the pharmacist to help you pick one,” the doctor suggested of drugstore shopping.

However, long stretches without improvement could indicate complications. The most common is pneumonia, when the infection moves from the upper respiratory tract to the lower.

“And as with a lot of things, we worry about the extremes, the youngest and oldest among us have a tougher time fighting off illnesses,” Rottinghaus said. “Kids, once they get sick, they can get sick fast.”

Worrisome symptoms include: shortness of breath, refusal to eat or drink, high fever, not acting “right.”

Despite the mismatch this year, experts still say the best act of prevention is an annual flu vaccine.

“Not only do I recommend that, but I will also still get one,” Rottinghaus said.

Here are confirmed cases of the flu in Butler County by season.2005-06: 742006-07: 332007-08: 3252008-09: 2142009-10: 7662010-11: 3302011-12: 312012-13: 9422013-14: 6782014-15 to Dec. 27: 442Statewide 2014-15 to Dec. 27: 10,117Source: Pennsylvania Department of Health