Health Advisory: Pertussis increase in Washington

| May 16, 2024

ACTIONS REQUESTED

BE AWARE of an increase in pertussis has been reported in some areas of Washington state and that patients with a history of receiving pertussis vaccine can still get pertussis. 

Persons at high risk for pertussis:  

  • Infants younger than one year or pregnant persons (e.g., childbirth educators, child care workers, members of a household with infants) 
  • Pregnant persons in the last trimester (who will expose infants)  
  • Healthcare workers with direct patient contact (who may expose infants, pregnant persons, or others who have contact with infants or pregnant persons)  
  • Anyone who may expose infants younger than one year or pregnant persons (e.g., childbirth educators, child care workers, members of a household with infants). 

CONSIDER pertussis infection in the following situations:  

  • Respiratory symptoms in infants younger than 12 months, especially if accompanied by difficulty feeding or apnea  
  • A cough illness, in patients of any age, that is characterized by one or more of the following:
    • Paroxysms  
    • Gagging, post-tussive emesis, or inspiratory whoop  
    • A duration of 2 weeks or more 
  • Respiratory illness of any duration in patients who have had contact with someone known to have had pertussis or symptoms consistent with pertussis

IF YOU SUSPECT PERTUSSIS IN A PATIENT:  

  • Consider testing. Collect a nasopharyngeal swab for pertussis polymerase chain reaction (PCR) or culture. PCR is the most sensitive and fastest diagnostic test. Culture is the most specific option, but not the most sensitive, and is rarely done. Note that serology should not be used for diagnosing pertussis cases in Washington.
    • Please note that a negative pertussis PCR or culture result cannot rule out pertussis. Treatment and case reporting may still be warranted, even with negative test results, per clinician’s assessment.  
    • CDC provides information about best practices for using PCR to diagnose pertussis. 
  • Report clinically-suspected pertussis cases within 24 hours to Kitsap Public Health District. Call Kitsap Public Health 24/7 at (360) 728-2235 during clinical encounter with a suspected pertussis case. We will assist you in determining recommendations for prophylaxis and exclusion. 
  • Assure children and adults are up-to-date on vaccine protecting against pertussis as recommended by national guidelines. Current vaccine schedules can be found on the CDC Immunization Schedules webpage.
    • Prioritize vaccination of household members and other close contacts of infants.  
    • Tdap is recommended during each pregnancy after 20 weeks gestation (ideally during weeks 27 through 36). 
  • Tell the patient to stay home from work, school, or childcare. Advise them that they are considered contagious until they have completed 5 full days of appropriate antibiotics.   
  • Follow CDC’s detailed treatment guidance. 
  • Consider preventive antibiotics for the entire household if a member meets any “High Risk” criteria (above). 

Diagnosing pertussis can be difficult, particularly during the early (catarrhal) stage of illness, which features non-specific symptoms and may not initially include a cough. For a patient with respiratory symptoms, known or suspected exposure to pertussis should prompt inclusion of pertussis in the differential diagnosis.

The incubation period for pertussis ranges from 5 to 21 days. A key feature that distinguishes pertussis from other common respiratory illnesses is the duration of the cough (usually longer than two weeks, and can last 10 weeks or longer). 

BACKGROUND

There have been a total of 170 confirmed and probable cases reported statewide during 2024 through 5/4/2024 (CDC Week 18), compared to 24 cases reported by CDC Week 18 in 2023, an increase of 6- fold. Multiple jurisdictions have reported increases. Current information about pertussis in Washington can be found in the DOH Weekly Pertussis Update. This report is updated every Friday. 

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. 

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