A handful of high school students in Santa Rosa and Sebastopol have come down with or been exposed to whooping cough, which is at its highest level of infection since 2014.

Two students at Montgomery High School contracted the highly contagious infection, a Santa Rosa City Schools official said.

One case was also reported at Analy High School in Sebastopol, West Sonoma County Union High School District officials said.

On Friday, Superintendent Chris Meredith and Analy Principal Chuck Wade sent a notice to parents stating that their children may have been exposed between Sept. 27 and Oct. 17.

Both districts sent out information to all parents on how to identify the infection.

Whooping cough starts out like the common cold with a runny nose, sneezing, and a low-grade fever. Symptoms get worse quickly; bad coughing attacks can lead to vomiting, problems breathing, extreme tiredness and other symptoms.

Cases of whooping cough, or pertussis, have been on the rise around the country since June. This year so far, California has reported 1,015 cases compared with 248 by this time last year, according to the most recent statistics from the U.S. Centers for Disease Control and Prevention.

“The outbreaks we’ve been experiencing are not a surprise,” said Dr. Tanya Phares, Sonoma County’s health officer. “They’ve been occurring throughout the fall and our public health nurses have been working closely with the schools.”

Phares added that the disease peaks every three to five years and tend to occur most in high school students as immunity wanes from the vaccine they received in seventh grade.

“Vaccination remains the best way to prevent pertussis (whooping cough),” Phares said. “In addition to vaccination, rapid identification of pertussis cases, appropriate treatment, isolation, and education about good respiratory etiquette helps prevent ongoing transmission.”

When schools report cases of whooping cough to the county’s public health, nursing staff provide guidance and investigate the circumstances of the outbreak, to mitigate further spread.

“We have observed an increase in pertussis cases in Sonoma County in 2024, following a cyclical pattern,” Phares said. “In response, we distributed health advisories and informational resources to clinicians and county schools this summer and fall.”

Report For America corps member Adriana Gutierrez covers education and child welfare issues for The Press Democrat. You can reach her at Adriana.Gutierrez@pressdemocrat.com.