Increase in Pertussis cases in several Washington Jurisdictions
Leigh Rowley
An increase in pertussis has been noted this year in some jurisdictions in Washington State, with a sixfold increase in reported pertussis cases statewide through week 18 (through 5/4/24) compared to cases reported by week 18 last year.
Actions Requested
Be aware of a resurgence in pertussis activity in some areas of the state. Please review the pertussis investigation guideline as needed.
Ensure that clinicians are aware that a negative pertussis PCR or culture result does not rule out pertussis.
A nasopharyngeal (NP) Swab is the preferred specimen, and PCR is the most sensitive and fastest diagnostic test. Culture is the most specific option, but only about 20% sensitive, and so is rarely done. Note that serology should not be used for diagnosing pertussis cases in Washington.
Pertussis testing is usually done commercially, but is available at the Public Health Laboratories (PHL) if needed (e.g., for patients with no health care coverage.)
Follow up on all reported confirmed and probable pertussis cases to offer prophylaxis to contacts for whom it is indicated. More information about post-exposure prophylaxis is available on pages 12 and 13 of the pertussis guideline.
Current Situation in Washington state
A total of 170 confirmed and probable cases have been reported statewide through 5/4/24 (CDC week 18) in 2024, compared to 24 cases reported by week 18 in 2023. Pertussis cases have been reported in 15 counties, with some reporting marked increases.
For more complete information, please refer to the Weekly Pertussis Update. This report is updated each Friday.
Background
Between 2010 and 2019, the median number of confirmed and probable pertussis cases reported per year was 685.5 cases statewide (mean: 1180 cases per year). A marked decrease in reported pertussis cases was observed in 2020; subsequently, fewer than 100 cases per year were reported during 2021 – 2023. The current increase in activity may represent a resurgence in pertussis.
Resources
DOH-LHJ Training Series Recording – Pertussis | December 2023 (SharePoint)
Pertussis Testing Video: Collecting a Nasopharyngeal Swab Clinical Specimen (YouTube) | CDC
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