OLYMPIA — The state Department of Health reported an increase in pertussis infections for 2024.
The state had 2,261 confirmed and probable cases reported last year, a 25-fold increase from the 87 cases recorded in 2023.
During 2024, Clallam County reported nine cases, or 11.5 cases per 100,000 people, and Jefferson County reported 10 cases, or 29.9 cases per 100,000 people.
Last year, the state reported its first pertussis-related death since 2011.
As of May 31, there already had been 1,314 cases reported statewide for 2025.
Clallam County has reported eight cases of pertussis, or 10.2 cases per 100,000 people, so far this year, and Jefferson County reported 13, or 38.9 cases per 100,000 people.
Neither county reported a case of pertussis in 2023.
Cases per 100,000 people is a way to present disease incidence rates to allow easier comparison between small counties, such as Jefferson, with a 2023 population of 33,424, and large counties, such as King with a 2023 population 2,347,799.
For example, the 166 cases in King County so far this year, although more than 15 times the number in Jefferson County, represent a rate of only 7.1 cases per 100,000, which is less one-fifth the rate in Jefferson County.
Pertussis, often called whooping cough, is a bacterial disease that can cause severe coughing spells.
Symptoms usually start five to 21 days after exposure and commonly include a runny or stuffy nose, sneezing, sore throat, cough and a general feeling of being unwell.
The constriction of the small air passages in very young patients causes a sharp “whooping” cough that gives pertussis its common name.
In severe cases, patients may temporarily stop breathing or develop pneumonia, convulsions, collapsed lungs, rib fractures or brain damage.
The disease is most dangerous for infants younger than 1 who may struggle to breathe and can become blue from not getting enough air.
Although it can be treated with antibiotics, it’s important to start treatment as soon as possible to minimize the symptoms and to help reduce the spread of the disease to others.
Officials point to declining vaccination rates, especially in children 19 to 35 months old, as the cause of the increase in pertussis infections.
The Department of Health recommends vaccination for those at higher risk of serious illness and people who have close contact with them.
People at a higher risk of serious illness include:
• Infants younger than 1.
• Pregnant people, especially during the third trimester.
• People with weakened immune systems or chronic respiratory illnesses.
• Adults older than 65 due to their higher susceptibility to pneumonia.
For more information, visit the department’s pertussis page at https://doh.wa.gov/public-health-provider-resources/notifiable-conditions/pertussis.
