1. 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

2. 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.

3. Pertussis Diagnostic Tests
Culture
PCR
Serology
DFA

4. 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

5. Reported Pertussis Cases in the United States: 1990-2008

6. Methods
Analyzed NNDSS data 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

7. Pertussis Diagnostic Trends: 1990-2008

8. Reported Test Type by Age: 2008

9. Proportion of All Reported Tests by Type

10. Most Common Test Combinations

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

12. 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

13. 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

14. 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

15. 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

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

17. 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

18. 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

19. Total Number of Reported Tests by Type