Trends in commercial laboratory testing and positivity for Bordetella species in the United States, 2019 through 2023.

Abstract

Background: Diagnostic methods for detecting infections caused by Bordetella species include culture, polymerase chain reaction (PCR), and serology. As the epidemiology of pertussis continues to evolve in the United States, we aimed to assess recent trends in provider testing practices and positivity for both B. pertussis and B. parapertussis.

Methods: Using deidentified data from a large U.S. commercial laboratory, we identified Bordetella tests from 2019 through 2023. We described monthly trends in number of tests ordered by test type for culture, PCR (both non-panel B. pertussis and B. parapertussis tests and those included as part of a respiratory panel), and serology, as well as percent positivity for serology and PCR. We also examined orders and positivity by patient age group and geographic region of the ordering provider.

Results: Among 527,206 tests, we identified 316,428 (60.1%) PCR tests, 204,480 (38.8%) serologic tests, and 5,840 (1.1%) cultures. While most PCR tests were ordered as part of a respiratory panel (83.5%), only 215 (0.08%) were positive for B. pertussis. Non-panel PCR positivity for B. pertussis was substantially higher but variable over the study period, ranging from 3% to 16%. We also observed a notable increase in B. parapertussis positivity on non-panel PCR tests in the first half of 2023.

Conclusions: Both PCR and serology remain preferred diagnostic methods for providers. Despite their increasing popularity, B. pertussis positivity remained low for respiratory panels. Data from commercial laboratories can provide crucial insights into pertussis diagnostic trends over time.