Pertussis on rise in Alameda County
Pertussis, commonly known as whooping cough, is on the rise this year in Alameda County, according to public health officials. A hundred and eighty cases have been reported since January, more than four times the number of reported cases during the same time period last year.
Alameda County public health officials say this increase could indicate another epidemic year for the highly contagious respiratory disease characterized by severe coughing.
Marin County is the only other Bay Area county that has seen a similar percentage increase, though the cases are declining again. Statewide numbers have remained stable this year, according to the California Department of Public Health.
Pertussis peaks cyclically, with surges occurring every three to five years. The most recent epidemic occurred in 2014, with more than 11,209 cases reported across California.
“We’ve been anticipating this,” said Dr. Erica Pan, director of Alameda County’s Division of Communicable Disease Control and Prevention. “Definitely in Alameda County at least, it looks like we’re trending toward an epidemic year and whether it’s more or less than 2010 or 2014 over the whole year, I think remains to be seen. But I don’t think we’re above and beyond necessarily prior epidemic years for the whole season.”
Though the disease can be relatively mild for most people, it can be deadly for infants, especially those in their first few months who haven’t been vaccinated. In 2014, there were two infant deaths and hundreds of hospitalizations in California. Federal and state health agencies recommend that pregnant women receive the Tetanus, diphtheria, and pertussis vaccine, or Tdap, during the third trimester.
“It’s a preventable disease and what we’re finding is that because immunity is waning, the best strategy from a public health perspective is to vaccinate every pregnant woman during every pregnancy,” Pan said. “So even if she was pregnant two years ago and got her pertussis booster then, we recommend she get another one now. It’s very safe and effective in pregnancy.”
The vaccination helps create an antibody that then passes through the placenta and ideally protects the baby from the bacterium in pertussis that is dangerous for infants, Pan said.
Since the early 1980s, pertussis cases have steadily risen, but in the past few decades, cases have surged noticeably. In 2010, California experienced its highest number of cases in more than 60 years, with more than 9,000 cases and 10 infant deaths. The reasons for the increase are unclear — some experts say it could be because the Tdap vaccine wears off more quickly than its predecessor, which had worse side effects, but longer-term immunity.
More than 60 percent of the cases in Alameda County this year are among high-schoolers, perhaps partially because the last vaccination required by the state is in 7th grade. The majority of cases in Marin County are also among high schoolers. “It’s likely that the reason we’re seeing this peak is that they’ve last been vaccinated about five years ago and now their immunity is waning,” Pan said. “So our message to everyone is really that pertussis can be a mild disease in most people, but the population we worry the most about are infants, young infants, especially those less than about 6 months of age.”
Health agencies recommend that infants receive vaccinations at 2, 4, and 6 months of age, and again between 15 and 18 months of age. Boosters are recommended between 4 and 6 years of age, and again between 10 and 12 years. The CDC recommends that adults receive their vaccination every 10 years, but more often if they are interacting with infants and young children. For more information visit: www.cdc.gov/ vaccines/vpd/pertussis/ recs-summary.html