California: Public Health Advisory issued in Marin County due to pertussis outbreak
Ongoing outbreak reported at Tamalpais High School
A Public Health Advisory has been issued in Marin County, California due to an outbreak of pertussis, or whooping cough.
In December 2023, Marin County Public Health began seeing a rise in reported pertussis cases, primarily among adolescents. Since December, the Communicable Disease unit has investigated 77 cases of pertussis, significantly elevated above normal rates.
52 cases are connected to an on ongoing outbreak at Tamalpais High School in Mill Valley.
During this surge in infections, no individuals have been hospitalized with pertussis and no cases among infants have been reported.
Pertussis is cyclic in nature, with peaks in disease every 3 to 5 years. These tend to occur in high school students as immunity wanes from the pertussis vaccine received in 7th grade.
Pertussis is a highly contagious respiratory infection caused by the bacterial pathogen, Bordetella pertussis. The incubation period is typically 7 – 10 days. Persons are infectious from the onset of cold-like symptoms until completion of five days of treatment or until 21 days after cough onset if no or partial treatment is given. Infants less than one year old are considered infectious for six weeks without treatment.
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Marin County health officials report vaccination is the best tool we have for preventing pertussis. The most effective strategy to protect infants who are most at risk for severe pertussis disease is to vaccinate all pregnant women during each pregnancy, preferably between 27 and 36 weeks of gestation. It is also important to vaccinate all children with the DTaP series on time and give a Tdap dose to adolescents and adults.
Although most children have been vaccinated for pertussis, protection from the vaccine wanes over time, so some who are fully vaccinated may still become infected.
During pertussis outbreaks, infants may begin the pertussis vaccination series at six weeks old.
In addition to vaccination, rapid identification of pertussis cases, appropriate treatment, isolation, and educating patients about good respiratory etiquette helps prevent ongoing transmission. Children and adolescents may return to school after completing five days of antibiotic therapy.
The Marin County order is in effect until further notice.