Whooping Cough Reaches 'Epidemic' Level in California

California health officials announced Friday that whooping cough (also known as pertussis) has reached epidemic levels in the state. The Department of Public Health reported 809 new cases of the infection, bringing the 2014 total to 3,458. That's 1,000 more cases than all of last year.

Four Bay Area communities have been hit particularly hard: Sonoma, Napa and Marin counties and Berkeley, which reports separately from the rest of Alameda County.

The overall state incidence rate is about 9 cases per 100,000 people, the CDPH says. But for Sonoma County the rate is 103 per 100,000; in Napa it's 65, and in Marin it's 53. Berkeley's rate is lower — 25 per 100,000; but that's three times higher than the rate for Alameda County as a whole. The rest of the Bay Area reports rates between a low of 6 per 100,000 in Santa Clara County and 17 per 100,000 in Solano County.

The CDPH said this year's epidemic is due at least in part to the cyclical nature of pertussis, which officials say peaks every three to five years. The last peak was in 2010, when the state had more than 9,000 cases and recorded 10 infant deaths connected to the disease.

But health officials say other factors may be at play, too. One suspected problem is the widespread use of acellular pertussis vaccines, which cause fewer negative reactions in patients than earlier vaccines but may not provide the long-lasting immunity.

Another widely discussed factor is that fewer children in some communities are receiving vaccinations for pertussis and other illnesses. That's because parents fearing potential harm from the vaccines are increasingly seeking "personal belief exemptions" (PBEs) that allow them to enroll children in school without getting state-required vaccinations. As we reported last summer, Marin County had a 7.8 percent PBE rate, the highest in the nine-county Bay Area. The statewide rate is 2.8 percent

But those PBE numbers alone don't appear to explain the pertussis spike in some locales. Santa Cruz County has a 9.6 percent personal-belief-exemption rate. But today's state figures show the county reporting a pertussis incidence rate of 11 per 100,000 — far below the North Bay counties and relatively close to the statewide rate. If you want to look up that PBE rate for schools in your community, search the database that KQED's State of Health blog posted last year.

Here's the latest Associated Press report on the whooping cough story:

Associated Press

LOS ANGELES — The number of whooping cough cases in California is now at an epidemic level, state health officials said Friday.

More than 800 whooping cough cases were reported over the past two weeks, suggesting that the infection, which is also known as pertussis, is spreading rapidly, according to a statement by the California Department of Public Health.

As of June 10, there were 3,458 reported cases — more than in all of 2013. There have been two reported infant deaths.

The infection is cyclical and peaks every three to five years, officials said. The previous whooping cough peak was in 2010, when an epidemic struck 9,159 people and killed 10 infants in the state.

Infants are most susceptible to the disease, so parents are encouraged to vaccinate their children as early as possible. Pregnant women are also encouraged to get vaccinated.

The disease has also raised national concerns. Although California is the only state to declare an epidemic, there has been a 24 percent increase of reported pertussis cases nationally from this time last year, according to the Centers for Disease Control and Prevention.

Whooping cough begins with cold-like symptoms and can progress to severe coughing fits that leave people gasping for breath.

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