Arizona's flu season is starting to kick into high gear, county health officials said Monday.
“Maricopa County is definitely seeing a rise in flu cases," said Susan Goodykoontz, epidemiologist with the state health department. “We're going to need to see what next week brings."
The clues are there: Monday was the busiest day of the year for Mesa-based Southwest Ambulance. The number of East Valley emergency room patients is escalating. And the state health department last week promoted the state's influenza status from “sporadic" to “regional."
Influenza, Goodykoontz said, is a mysterious bird; there is no rhyme or reason for when and why it may flourish. “All of the sudden it will just explode," Goodykoontz said. “We'll see it change in a day."
Local health care organizations have seen an upswing in influenza cases over the past week.
Southwest Ambulance had transported 111 patients by 4 p.m. Monday — 10 more than the year-round average, and the highest number so far this year. The jump in service is attributable to the influx of winter residents and the beginning of flu season, said Southwest Ambulance spokesman Josh Weiss.
“When all the winter visitors come, they bring all their health problems with them," Weiss said.
Administrators at Desert Samaritan Medical Center in Mesa saw emergency room numbers jump from an average of 260 to 340 on Saturday and more than 300 patients on Sunday and Monday, said Ingrid Batchel, clinical administrator for the hospital's emergency room.
It is impossible to track the number of influenza cases because so few are examined at a laboratory. But Batchel said that more than half of Desert Samaritan's cases exhibit respiratory symptoms.
Scottsdale Healthcare hospitals and Mesa Lutheran Medical Center, however, have seen only a handful of influenza cases.
Health care experts have been waiting for the flu all winter, when people tend to congregate indoors where air and body fluids mingle, said Ron Cheshier, virology section manager at the state laboratory.
“It's more human dynamics than biodynamics," Cheshire said.
Dr. Chris Price, medical director of Mesa Lutheran's emergency room, said it is not too late to get a flu shot. He encourages the public to watch for influenza symptoms, including fever, sore throat, muscle aches and cough. If caught within the first two days, medications can curb the virus, he said.
This is the third year in a row in which flu season has taken its hold on Arizona later than expected, Goodykoontz said. Arizona's first flu case was reported Dec. 9 — a full two months earlier than in previous years. Last year, influenza season in Arizona peaked during the first week of February.
The only indicator of when the flu may strike Arizona is by keeping tabs on the disease around the country, Goodykoontz said. As of Monday, only Missouri, Texas and Virginia had peaked, according to the Centers for Disease Control and Prevention's Web site.
Each year, between 20,000 and 40,000 Americans die from influenza and pneumonia — with more than 90 percent involving people age 65 and older, according to the CDC.
In Arizona, approximately 1,100 people died from flu and pneumonia last year.