PHOENIX — A huge spike in the number of flu cases could portend a particularly bad season for Arizona.

New figures from the Arizona Department of Health Services show there have been 1,143 cases so far this season. That’s compared with 157 at the same time last year.

And that 2016 figure was not an aberration. The average to this date for the five seasons before this one is just 142.

What makes this number so potentially alarming is the timing: The number of new cases reported each week does not normally peak until February

But Jessica Rigler, the agency’s bureau chief for public health preparedness, said she’s not prepared to say at this point that the pattern being set — 385 new cases this past week alone versus 43 the same week last year — will lead to some new record in the number of people who get infected.

“Flu is really difficult to predict,” she said. “It behaves differently every single season.”

Still, there have not been any recent spikes locally in patients with the flu seeking emergency care, say officials at Tucson Medical Center, which is one of the state’s busiest emergency departments.

“We have not seen a huge influx of flu cases,” TMC’s emergency department director Cynthia Carsten said.

Carsten said that locally the flu usually peaks between January and March and typically that’s reflected by higher patient volume in the emergency department.

Officials with Banner-University Medical Center Tucson, 1501 N. Campbell Ave., say they have not seen any spike in flu cases in the emergency department, either.

Pima County has had 175 reported cases of flu so far this season. At this time last year, the number was just 24, state records show.

State officials say the number of reported cases does not represent the true number of cases of influenza, since many people do not visit the doctor when ill and doctors do not run tests on all patients exhibiting flu-like symptoms.

“Cases have increased over the last couple of weeks and people really need to be taking steps to protect themselves,” said Aaron Pacheco of the Pima County Health Department. “It is still too early to tell how severe this season will be. It is clear though, that it is time to get vaccinated if you haven’t already.”

Rigler said it may just be that people are getting the flu earlier in the season than normal. And that would mean the peak will be sometime before February. “Or it’s possible we’ll have more cases overall this year,” she continued. “It’s jut a little too soon to tell.”

As to why the virus is showing up so early, Rigler has one theory.

“The majority of our cases are influenza A, the H3 type, which is the same as what we saw last flu season,” she said. And that last season, Rigler continued, lasted unusually long, into the summer months, with 100 or more cases a week into June and July.

“So it’s possible that we never really saw a complete end to last year’s flu season and we’re just picking up where we left off,” she said.

What about the possibility that this strain — formally known as H3N2 — has become resistant to the vaccine? “It’s difficult to say,” Rigler said.

“Ususally we’ll get some of those flu vaccine effectiveness studies that come out in the early part of next year,” she explained. “But right now we really don’t have any great estimate for the U.S. and how effective our flu vaccines are so far this year.”

Still, Rigler said the best defense is a flu shot — even now.

“Even though we’re seeing an increase in cases right now, this might not be the end,” she said. “That’s especially important right now as we enter the holiday season because people are spending more time with loved ones, including those that are very vulnerable to the complications from flu, like the elderly or infants.”

Still, she acknowledged, the protection is not immediate. Rigler said it takes about two weeks for the body to react to the vaccine to build up an immunity.

There’s also the other method of self-defense: washing hands.

“And if you are feeling under the weather, it’s important to stay home from school or from work so you’re not infecting others, and to cover your coughs and sneezes with your arms so you’re not spreading germs around,” she said.

Carsten cautions that people who visit emergency departments with the flu risk getting other people sick, particularly those who are immune-compromised.

“We recommend they first try to prevent the flu by washing their hands and getting a flu shot — especially if they are high risk, like aging adults and pregnant women,” she said.

Also, stay home if you are sick, she said. If you do need medical attention, contact your primary-care doctor. Urgent care and emergency departments are always options, too, she said.

Every year about 4,000 Arizonans are hospitalized because of influenza.

On Twitter: @azcapmedia