Key points
- CDC tracks pertussis cases using a national surveillance system.
- CDC works with several states on enhanced pertussis surveillance.
- Cases have increased over the last few decades but remain low.
- Experts believe that much of the disease goes unrecognized and unreported.
Data systems
National Notifiable Diseases Surveillance System
Pertussis is a nationally notifiable disease.
Healthcare providers should notify the appropriate health department of all patients with suspected pertussis.
Diagnostic laboratories should notify health departments of all positive pertussis laboratory results.
State health departments then report pertussis cases to CDC through the National Notifiable Diseases Surveillance System (NNDSS). NNDSS is useful for monitoring epidemiologic trends in disease over time.
Enhanced pertussis surveillance
CDC partners with seven states participating in the Emerging Infections Program network to conduct enhanced pertussis surveillance (EPS). This network also conducts surveillance on other Bordetella species.
EPS sites
- Conduct enhanced case ascertainment and augmented data collection.
- Collect isolates and specimens for further characterization at CDC.
- Provide infrastructure for conducting pertussis special studies.
This additional information goes beyond what CDC receives through NNDSS.
How the data are interpreted
Pertussis cases before widespread vaccination
In the 20th century, pertussis was one of the most common childhood diseases and a major cause of U.S. childhood mortality. Before the availability of a pertussis vaccine in the 1940s, public health experts reported more than 200,000 cases of pertussis annually.
Pertussis cases from the 1940s to 1980s
Widespread use of the vaccine began with the introduction of the diphtheria, tetanus toxoid, and whole-cell pertussis (DTP) vaccine in 1948. Since then, the number of cases each year has decreased more than 90%, compared with the pre-vaccine era.
Pertussis cases since the 1980s
During the 1980s, pertussis reports began increasing gradually, leading to a peak in 2012 with 48,277 reported cases. Since then, reported cases remained elevated until the start of the COVID-19 pandemic in 2020.
Several factors have likely contributed to the increase in reported cases, including
- Improved recognition of pertussis by healthcare providers
- Greater access to and use of laboratory diagnostics
- Increased surveillance and reporting to public health departments
- Waning immunity from acellular pertussis vaccines
Impact of genetic changes
Bordetella pertussis, the bacteria that cause pertussis, are always changing at a genetic level. CDC continues to evaluate what impact, if any, molecular changes in B. pertussis are having on public health.
Infants experience highest incidence
Infants under one year old are at greatest risk for serious disease and death because their immune systems are still developing. This age group continues to have the highest reported rate of pertussis.
Data reporting
NNDSS
View NNDSS infectious disease data tables.
Pertussis surveillance reports
View pertussis data, including case counts and incidence by state and age, DTaP vaccination history of cases, and pertussis-related deaths.
These and older surveillance reports can be found at CDC Stacks.
Data definition
The Council of State and Territorial Epidemiologists (CSTE) published the most recent case definition for pertussis in 2020.