State declares whooping cough epidemic

California health officials declared a whooping cough epidemic in the state Friday after what they said was an unexpected surge of cases.

More than 900 new cases of the illness, also known as pertussis, were reported in both April and May, well above normal, officials said in a statement. Overall, 3,458 cases and one death have been reported this year, they said.

Whooping cough is a highly contagious bacterial disease that primarily affects infants and children.

Marin, Sonoma and Napa counties have the state's highest infection rates. San Francisco County's count is at 36, with two school outbreaks, no hospitalizations and no infant infections to date.

California officials said they were working closely with local health departments and schools to inform the public of the importance of vaccinations, the Associated Press reported.

"The real reason we fear it is that it kills young infants," said Dr. David Witt, an infectious disease specialist at Kaiser Permanente San Rafael. "In adults, it can be extremely annoying - one translation of the Chinese name for it is the 'hundred days cough,' for perspective. [But] in young infants, it actually kills."

Symptoms include a runny nose, congestion, sneezing, mild fever and a dry cough that worsens with time. It spreads when infected people cough and sneeze. Infant symptoms differ from those of adults: They don't always have a cough, but may gag, gasp and turn red in the face, public health officials said.

Infants, children and teenagers made up 84 percent of cases statewide. California elementary, middle and high schools have seen outbreaks this year.

The epidemic isn't as striking in San Francisco as it is statewide, said Dr. Cora Hoover, director of communicable disease control and prevention for the city's Department of Public Health.

The one reported death involved a 2-month-old baby who contracted the infection at 2 weeks old. There have been 119 hospitalizations, 21 of which required intensive care.

Babies are generally vaccinated for pertussis at 2, 4 and 6 months. Children are vaccinated at 15 months, before kindergarten, and again at age 11 or 12, Hoover said. Adults should have one booster shot.

Pregnant women are advised to be vaccinated for whooping cough during each pregnancy so their children are born with antibodies, Witt said, adding that those who care for infants should be extra careful because they can pass the bacteria to babies, whose vaccinations aren't effective until after they are 6 months or older.

Pertussis outbreaks have occurred on a three- to five-year cycle since the early 2000s - partly due to a change in vaccine and partly due to changes in the bacteria that causes it, Witt said. Also at issue is that California allows parents to opt out of vaccinations, creating a "reservoir of unvaccinated children," he said.

California's last epidemic was in 2010, when there were 9,159 reported cases and 10 infant deaths.