It's official. The flu bug is to blame for the sore throats, coughs and headaches that are keeping people home from work and children out of school across the central San Joaquin Valley.
And doctors say to expect more empty desks at work and in classrooms the next few weeks. Flu season hasn't reached its peak, and the virus could hang around until April.
"It kind of started creeping up the week of Christmas," said Dr. Dee Lacy, an infection specialist at Kaiser Permanente Medical Center in Fresno. "It's just been going up almost linearly since then."
Northern California Kaiser hospitals, including the one in Fresno, test people with flulike symptoms for the virus. In December, about 8% of the tests returned positive, Lacy said. This past week, 35% were positive.
Children's Hospital Central California in Madera County is seeing the same increase in positive flu-test results. In the last two weeks, the hospital has had 62 confirmed flu cases -- 46 recorded since Monday. But only a handful of children have been admitted for severe flu symptoms, a spokeswoman said.
Employers and school nurses don't need test results to confirm it's flu season.
In the Clovis Unified School District, 120 students -- about 10% of the student body -- were absent Wednesday from the Clovis North Educational Center, an intermediate and high school. And Clovis West High School had about that many out on Thursday. The district's high schools typically have about 50 students a day out sick, said Carol Padilla, the district's coordinator of nursing services.
Children with high fevers and achy bodies have been keeping Annamarie Brown, pediatric nurse practitioner, busy at the health clinic at Pinedale Elementary School in Fresno.
"They come to school, and they'll just spike a temp here at school, and once they have a temp, they're considered contagious and they go home," she said. "And some come back too early and they spread it again."
Brown and fellow school nurses have compared notes about the flu. The worst case she heard involved a student who came ill to school on a Friday and went on a class field trip. "On Monday, there were 13 kids out in his class," she said.
Employers are also feeling the pinch from the flu, said Ruth Evans, owner of The Evans HR Group, a Fresno human resource services company.
"Virtually all our clients have certainly been affected by people taking off because of the flu," Evans said. "I don't know any employer who has escaped it."
With flu season likely to continue through April, county health officials say it's not too late to get a flu shot. People should check with their doctors about getting the vaccine. But county health departments have some vaccine left.
Madera County has 560 doses, said Dr. Thomas E. Cole, the health officer. "We'll give it to anybody," Cole said. "We'd like to get rid of it."
The flu shot should offer protection for influenza A, the most common strain that is circulating this year, said Lacy of Kaiser. But it's less likely to prevent cases of flu from influenza B, which has also been detected but is making far fewer people sick, she said.
Antiviral medications can help if given within 48 hours of the start of symptoms, Lacy said. But some cases of resistance to the medications have been reported worldwide. The drugs should be reserved for those who are more likely to get complications from the flu -- the elderly, or people with heart or lung disease, or who have cancer or other chronic health conditions, she said.
It's not all bad news.
"It's a fairly mild season as far as how sick people are getting," Lacy said.