Health Advisory: Pertussis increase in Washington, remain alert for patients with symptoms

May 21, 2024

Action Requested

• Be aware of an increase in pertussis reported in some areas of Washington State and that patients with a history of receiving pertussis vaccine can still get pertussis. Consider the diagnosis of pertussis in the following situations: 
  • Respiratory symptoms in infants <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. 
    • Given that pertussis circulation appears to be increasing locally, consider testing for mild respiratory symptoms when lasting more than 2 weeks and for any duration when a contact is known or suspected.
• 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 any suspected or confirmed cases of pertussis in Snohomish County to the Snohomish County Health Department.
  • Call 425-339-3503 to reach the Communicable Disease program by phone.
  • Please complete and fax the Communicable Disease Report Form (PDF) and any accompanying lab reports to 425-339-8706. 
• Assure children and adults are up-to-date on pertussis-containing vaccine 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). 

If you strongly suspect pertussis:

• Treat: CDC provides detailed treatment guidance.
• Exclude: 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. 
• Report the illness to the Snohomish County Health Department (425-339-3503) within 24 hours.
• Consider preventive antibiotics for the entire household if a member meets any “High Risk” criteria.
  • Persons at high risk for pertussis include:
    • Infants <1 year old (who are at greatest risk for severe disease and death)
    • 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 < 1 year old or pregnant persons (e.g., childbirth educators, child care workers, members of a household with infants).

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. Additionally, illness in partially immunized individuals or breakthrough disease in individuals who are up to date can be mild. For a patient with respiratory symptoms, known or suspected exposure to pertussis should prompt inclusion of pertussis in the differential diagnosis. Suspicion for pertussis should be elevated currently given apparent increasing local transmission, and clinical testing threshold should be lowered. 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). This can be very mild in breakthrough disease in partially or fully immunized individuals.

Background

There have been a total of 183 confirmed and probable cases reported statewide during 2024 through 5/11/2024 (CDC Week 19), compared to 24 cases reported by CDC Week 19 in 2023. 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. 

Resources

• CDC: Pertussis Clinical Features https://www.cdc.gov/pertussis/clinical/features.html 
• CDC Pertussis Testing Video: Collecting a Nasopharyngeal Swab Clinical Specimen https://www.youtube.com/watch?v=zqX56LGItgQ 
• CDC: Pertussis Treatment for Clinicians https://www.cdc.gov/pertussis/clinical/treatment.html
• CDC: Best Practices for Healthcare Professionals on the use of PCR for Diagnosing Pertussis https://www.cdc.gov/pertussis/clinical/diagnostic-testing/diagnosis-pcr-bestpractices.html 
• DOH Weekly Pertussis Update https://doh.wa.gov/sites/default/files/legacy/Documents/Pubs/348-254-PertussisUpdate.pdf
• ACIP Immunization Schedules https://www.cdc.gov/vaccines/schedules/hcp/index.html

MESSAGE CATEGORIES

• Health Alert: High-importance information about a public health incident. Warrants immediate action.
• Health Advisory: Important information about a potential or ongoing public health incident. May not require immediate action.
• Health Update: Updates about an ongoing public health incident. Immediate action not required.