Marin County dealing with whooping cough outbreak

Marin County is experiencing a significant increase in whooping cough cases, primarily centered on one of its largest high schools.

The county’s health officer, Matt Willis, issued an advisory last week indicating that out of the 93 cases recorded in the region since mid-December, 65 have occurred at Tamalpais High School in Mill Valley.

Whooping cough, also known as pertussis, is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. It manifests as prolonged bouts of coughing, often accompanied by a distinctive whooping sound when a person inhales. Typical symptoms resemble a common cold, including a runny nose and fever.

While the persistent cough can last more than 10 weeks, it seldom results in severe health complications for healthy individuals.

During the current outbreak, Marin County health officials have reported no hospitalizations due to pertussis and no cases among infants.

Although whooping cough can be relatively mild for most people, it can be fatal for infants, particularly those in their first few months who have not yet been vaccinated.

Testing for pertussis is available through a physician’s office, either by an evaluation or a nasal swab test.

If a person tests positive, the physician can prescribe the antibiotic azithromycin for a required five-day isolation period.

To mitigate the spread of whooping cough, doctors commonly recommend DTaP vaccinations.

Even those who have been vaccinated may still contract the disease, but they generally experience less severe symptoms, Willis said.

Pertussis peaks cyclically, with surges occurring every three to five years. Marin County reported its last whooping cough outbreak during the 2018-19 winter season, with approximately 300 cases reported. Alameda County experienced a surge at that time as well.

High school students are often the most affected due to the waning immunity from the pertussis vaccine they typically receive in seventh grade.

Officials previously attributed a high rate of whooping cough cases in Marin County to its relatively low vaccination rates compared with other Bay Area counties. But that figure has dramatically improved in recent years. As of the 20212022 school year, nearly 97% of kindergartners in the county were up to date on their required immunizations compared with just 78% a decade earlier.

In 2023, there were 589 whooping cough cases reported across California.