Nov. 1, 2024

Health Advisory: Update on local pertussis activity

ACTIONS REQUESTED

BE AWARE of local pertussis activity and consider pertussis in patients exhibiting symptoms of respiratory illness.

Diagnosing pertussis can be difficult, particularly during the early (catarrhal) stage of illness, which may present with non-specific symptoms and might not initially include a cough. Pertussis should be included in the differential diagnosis of patients with respiratory symptoms and/or a known or suspected exposure to pertussis.

The incubation period for pertussis ranges from five to 21 days. A key feature distinguishing pertussis from other common respiratory illnesses is the duration of the cough (usually longer than two weeks and can last 10 weeks or longer) and post-tussive gagging, post-tussive emesis, or inspiratory whoop. 

Persons at high risk for pertussis:  

• Infants younger than 12 months or pregnant persons in the last trimester.

High-risk contacts that should be considered for chemoprophylaxis if exposed to pertussis: 

• Infants younger than 12 months.
• Pregnant persons in the last trimester (who will expose infants).  
• Anyone who may expose infants younger than one year or pregnant persons (e.g., childbirth educators, childcare workers, members of a household with infants or pregnant persons). 
• Household members of a confirmed case of pertussis.

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

REVIEW IMMUNIZATION HISTORY AND RECOMMEND PERTUSSIS VACCINE for patients who meet CDC recommendation criteria and are not up to date. CDC recommends DTaP and/or Tdap for the following groups:

• Infants and children: CDC recommends routine DTaP vaccination for all infants and children younger than 7 years old.
• Adolescents: CDC recommends a single dose of Tdap at 11 to 12 years of age for all adolescents.
• People who are pregnant: Give a single dose of Tdap during every pregnancy, preferably during the early part of gestational weeks 27 through 36.
• Adults who have never received Tdap: CDC recommends a single dose of Tdap for adults who've never received Tdap. It can be given at any time, regardless of when they last got Td.

Additional information on vaccine recommendations, contraindications, and catch-up guidance can be found on the CDC website.

IF YOU SUSPECT PERTUSSIS IN A PATIENT:  

• Test. Collect a nasopharyngeal swab for pertussis polymerase chain reaction (PCR) or culture. PCR is the most sensitive and fastest diagnostic test and is most effective when the specimen is collected within three weeks of cough onset. Culture is more specific and can differentiate between Bordatella species, but is less sensitive than PCR and may miss some infections. Serology is generally NOT a recommended laboratory method for diagnosis of pertussis due to high observed variability of clinical accuracy.
• 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. 
• Consider testing for other circulating respiratory pathogens, including influenza, SARS-CoV-2 (COVID-19), and respiratory syncytial virus (RSV). Information on circulating respiratory viruses can be found in our weekly Respiratory Illness Report, and the University of Washington Virology Lab’s Respiratory Virus Dashboard.
  
  
• 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. 
  
  
• Advise the patient to stay home from work, school, childcare, or other social activities such as sports or church. Patients are considered contagious until they have completed 5 full days of appropriate antibiotics or 21 days after symptom onset.
  
  
• Follow CDC’s detailed treatment guidance. 
  
  
• Consider preventive antibiotics for the entire household if a member meets any “High Risk” criteria (above). 

BACKGROUND

Both the U.S. and Washington state have observed a large increase in pertussis cases reported in 2024, compared to 2023. Preliminary national data show that more than five times as many cases have been reported as of week 43 (as of October 26, 2024) compared to the same time in 2023. In Washington state, there have been 1,008 cases reported this year through October 19, 2024, or a 22-fold increase from this time last year.

As of Nov. 1, there have been two cases of laboratory-confirmed pertussis reported in Kitsap County, but other indicators suggest that wider transmission has been occurring in the community. The last major pertussis outbreak in Kitsap County occurred during the 2014-15 school year, primarily affecting high school students. In total, there were 122 confirmed and probable cases, plus 31 suspected cases.

Current information about pertussis in Washington can be found in the DOH Weekly Pertussis Update. This report is updated every Friday. 

School vaccination data collected in September 2023 show an overall decrease in the percent of Kitsap kindergartners who are up-to-date on pertussis-containing vaccines compared to 2019, increasing the risk of pertussis transmission in schools. Pertussis vaccine is 98% effective within 12 months of the final dose of DTaP.

Pertussis activity tends to peak every three to five years, with occasional largescale epidemics. The last major pertussis epidemic in Washington state occurred in 2012, with a total of nearly 5,000 cases, 105 hospitalizations and one infant death.