Evolution of Pertussis Diagnostic Testing in the U.S. : 1990-2008 National Immunization Conference April 22, 2010 Atlanta, GA Amanda Faulkner, MPH Meningitis and Vaccine Preventable Diseases Branch National Center for Immunization and Respiratory Diseases Centers for Disease Control and Prevention

Background Pertussis is a poorly controlled bacterial vaccine preventable disease caused by Bordetella pertussis: Fastidious gram negative coccobacillus Historically occurs in cycles, with peaks every 3-5 years Despite high childhood vaccine coverage, pertussis remains a public health problem in the U.S.

Pertussis Diagnostic Tests Culture PCR Serology DFA

CSTE Case Definition for Pertussis Clinical case definition: Cough ≥2 weeks AND paroxysms, inspiratory whoop, or posttussive vomiting Probable Confirmed -Meets clinical case definition - Culture positive + cough any duration - PCR positive* + clinical case definition - Epi link* + clinical case definition *Added to the CSTE case definition in 1997

Reported Pertussis Cases in the United States: 1990-2008

Methods Analyzed NNDSS data 1990-2008 for all reported cases of pertussis Identified all laboratory tests performed on each case reported Lab test reported did not have to be positive to be included

Pertussis Diagnostic Trends: 1990-2008

Reported Test Type by Age: 2008

Proportion of All Reported Tests by Type

Most Common Test Combinations

Reported Serology Tests, 1995-2008: MA vs. Remaining U.S.

Key Findings PCR has replaced DFA and culture as the dominant pertussis diagnostic test The reporting of multiple test types for diagnosis has declined significantly Serologic testing is reported in a significant proportion of states for pertussis diagnosis

PCR Pros Cons High sensitivity Results can be obtained quickly Organism does not need to be viable Less affected by immunization and antibiotics Cons No standardized reagents or interpretation of results Most labs only use single targets Affected by disease phase and antibiotic treatment False positives and contamination

Serology Pros Cons Can be used later in disease course Less affected by antibiotic treatment Cons No standardized test May be affected by recent immunization Not useful during first 2 weeks of illness Not currently included in CSTE case definition

Optimal Timing for Diagnostic Testing Communicable Period Convalescent Stage Incubation Period Paroxysmal Stage Catarrhal Stage -3 2 8 12 Bacterial Culture Symptom Onset PCR Serology

Current and Future Efforts Serologic assay kit Multi-target PCR assay Pertussis Clinical Validation Study APHL lab training Revisit the CSTE case definition

Conclusions No single laboratory test can stand alone for diagnosing pertussis Adopt standardized and improved PCR methods Serology is a useful method for diagnosing pertussis especially in adults and in late stage disease Consideration should be given to including in CSTE case definition Labs should maintain culture capabilities Pair PCR with culture testing for optimal results, especially during outbreak situations

Acknowledgements Stacey Martin Christine Mitchell Tami Skoff Tom Clark Grace Ejigiri Nancy Messonnier Lucia Pawloski Kathi Tatti Monte Martin Kathryn O’Connell Lucia Tondella Pam Cassiday

Total Number of Reported Tests by Type