Health Advisory: Increased Cases of Pertussis in Snohomish County—Be Alert for Patients Exhibiting Symptoms

10/3/2024

Action Requested

• Be aware of an increase in pertussis reported in Snohomish County, Washington State, and across the country
  • There has been a total of 780 cases reported statewide so far in 2024.
  • Snohomish County has reported more than 52 confirmed and probable pertussis cases year-to-date with a large uptick in cases since the beginning of September. 
  • This increase is disproportionately impacting younger children (aged 0-4) and older teenagers (aged 15-19) who collectively make up more than two-thirds of Snohomish County cases in 2024.
• Recommend DTaP or Tdap vaccines that protect against pertussis to those who have not received it or need a booster 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.
  • Babies and young children should receive multiple doses of DTaP between ages 2 months and 6 years.
  • Preteens (ages 11-12), or any teen or adult who has not yet been vaccinated, should receive the Tdap vaccine.
  • Tdap is recommended during each pregnancy after 20 weeks gestation (ideally during weeks 27 through 36).
  • Vaccine hesitancy, even for routine childhood immunizations like this one, has increased since the pandemic. It is likely that many of our cases are attributable to delayed or missed pertussis immunizations. 
• Know 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 is 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.

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 household contacts and other contacts that meet 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).

Background

For additional information, see our recent press release. 

Current information about pertussis in Washington can be found in the DOH Weekly Pertussis Update.  

Resources

• CDC: Pertussis Clinical Features Clinical Overview of Pertussis | Whooping Cough | CDC
• CDC Pertussis Testing Video: Collecting a Nasopharyngeal Swab Clinical Specimen https://www.youtube.com/watch?v=zqX56LGItgQ 
• CDC: Pertussis Treatment for Clinicians Treatment of Pertussis | Pertussis (Whooping Cough) | CDC
• CDC: Best Practices for Healthcare Professionals on the use of PCR for Diagnosing Pertussis Best Practices for Use of Polymerase Chain Reaction for Diagnosing Pertussis | Whooping Cough | CDC
• 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/hcp/imz-schedules/index.html 
• Snohomish County Health Department Pertussis Fact Sheet: https://snohd.org/DocumentCenter/View/98/Pertussis?bidId=