A fifth person in the central San Joaquin Valley has died of influenza in the past week, adding to a growing number of flu-associated deaths in the state.
The death was the second for Kings County, which reported its first death on Thursday. The same day, Fresno County reported a death and Merced reported two.
Health officials said how much the flu spreads in coming weeks will depend on how many people get vaccinated. Flu season in California typically peaks in January and February.
But influenza is now "widespread" in California, state officials said.
Dr. Gil Chavez, the state epidemiologist and deputy director for infectious disease, said the number of confirmed flu cases "is rising rapidly and exceeds what is expected for this time of year."
And one particular flu germ is making most people sick: H1N1 influenza A -- a strain very similar to the 2009 pandemic flu.
"As of today, there is no evidence that the flu's H1N1 strain has changed in any significant way to make it act differently than it did in the pandemic," Chavez said Friday during a teleconference in Sacramento.
The pandemic five years ago was responsible for 607 deaths statewide. In the Valley, there were 38 deaths -- 20 from Fresno County -- between April 2009 and August 2010.
So far this year, deaths associated with the flu have not reached epic numbers, but it's too soon to know if the virus has reached its peak.
As of Jan. 4, California had seven confirmed deaths -- they do not include the five Valley patients -- and another 28 statewide are under investigation. State numbers lag behind county reports because of the time needed to investigate.
The deaths also don't include the elderly. Since the 2009 pandemic, the state has required hospitals to report influenza-associated hospitalizations and deaths -- but only for people under age 65.
While the elderly are at increased risk from the flu, the H1N1 flu strain, which Fresno County health officials said has been improperly called swine flu, causes severe illness in all age groups. Even young, healthy people are at increased risk, and the flu is particularly dangerous for pregnant women.
The two men who died in Kings County were both middle-aged, and the first patient who died had no underlying medical conditions, county health officials said.
The cases have Kings County health officials concerned, and they plan to increase surveillance at hospitals to include patients admitted for respiratory illnesses who do not require intensive care, said Sharon Soong, the county's communicable disease coordinator.
Valley hospitals have seen a spike in feverish, coughing flu patients.
Saint Agnes Regional Medical Center in northeast Fresno had only one patient test positive for the flu in November, but in one day this week -- Wednesday -- the hospital had six patients, said spokeswoman Jaime Huss.
At Kaiser Permanente facilities, positive tests for influenza increased from about 9% three weeks ago to 28% last week, and with children returning to schools, Kaiser is girding for even more flu patients.
"We're all kind of waiting with bated breath to see what our numbers are for this week," said Dr. Randy Bergen, the clinical lead for Kaiser Permanente Northern California's flu campaign and a pediatric infectious disease specialist. "But we're clearly in the middle of a very brisk and serious influenza season."
Fresno County health officials urged parents to keep children home if they have a fever, sore throat or cough. "Make sure you do not send sick kids to school," said David Luchini, assistant director of the county's Department of Public Health.
One encouraging sign: People are getting vaccinated.
Fresno County's immunization clinic is busy, Luchini said Friday. "We'll probably hit 100 vaccines administered here today in this clinic -- maybe even more."
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