Reports on pertussis, commonly known as whooping cough, have shown a significant trend. After a period of unusually low cases during and after the COVID-19 pandemic, the United States is observing a resurgence. This marks a return to pre-pandemic patterns, where annual cases typically exceed 10,000. The decline in cases during the pandemic is likely attributable to mitigation measures such as masking and remote learning, which reduced the transmission of respiratory illnesses like pertussis.
In 2024, there has been a notable increase in reported pertussis cases across the nation, signaling a return to typical epidemiological trends. Preliminary data indicates a more than sixfold increase in cases reported as of week 52, ending on December 28, 2024, compared to the same period in 2023. Alarmingly, the case numbers in 2024 have surpassed those reported in 2019, before the onset of the pandemic.
Vaccination remains the most effective method for pertussis prevention. However, with the resurgence of typical infection patterns, the Centers for Disease Control and Prevention (CDC) anticipates an increase in pertussis cases in both vaccinated and unvaccinated populations. This is because vaccine-induced protection against pertussis diminishes over time. State and local health departments are well-prepared to address these increasing trends and implement appropriate control measures.
Pertussis Data Availability
The most current pertussis data reported to the CDC is accessible online through the National Notifiable Diseases Surveillance System (NNDSS). It’s important to note that due to reporting lags and data verification processes, the most up-to-date information is often available directly from state and local health departments.
View the latest data available from CDC
National Notifiable Diseases Surveillance System (NNDSS)
Pertussis is classified as a nationally notifiable disease. This designation mandates that healthcare providers report all suspected pertussis cases to their local health department. Similarly, diagnostic laboratories are required to report all positive pertussis laboratory results to health departments.
State health departments, in turn, report these cases to the CDC through the NNDSS. The NNDSS is a crucial tool for monitoring the epidemiological trends of diseases over time, providing valuable insights into disease patterns and public health responses.
Keep Reading: National Notifiable Diseases Surveillance System (NNDSS)
Enhanced Pertussis Surveillance
The CDC collaborates with seven states as part of the Emerging Infections Program (EIP) network to conduct enhanced pertussis surveillance (EPS). This network also extends its surveillance to other Bordetella species, offering a broader understanding of related respiratory infections.
EPS sites are involved in:
- Comprehensive case identification and detailed data collection.
- Collection of isolates and specimens for in-depth characterization at the CDC.
- Providing infrastructure for specialized pertussis research studies.
The EPS program gathers supplementary information beyond what is routinely collected through the NNDSS, enriching the depth of data available for analysis and public health action.
Interpreting Pertussis Data: Historical Context for Cough Diagnosis
To effectively utilize pertussis data in cough diagnosis and public health planning, it’s essential to understand the historical context of the disease, particularly in relation to vaccination eras.
Pertussis Before Widespread Vaccination
In the early 20th century, pertussis was a prevalent childhood illness and a significant cause of child mortality in the U.S. Before a pertussis vaccine became available in the 1940s, public health records showed over 200,000 cases annually. This historical data underscores the dramatic impact of vaccination on disease prevalence and severity.
Pertussis Cases: 1940s–1980s
The introduction of the diphtheria, tetanus toxoid, and whole-cell pertussis (DTP) vaccine in 1948 marked a turning point. Widespread vaccination efforts led to a remarkable reduction in pertussis cases, with annual numbers decreasing by more than 90% compared to the pre-vaccine era. This period highlights the success of early vaccination programs in controlling pertussis.
The graph visually represents the significant decline in pertussis cases following the introduction and widespread use of vaccination, demonstrating its long-term effectiveness.
Pertussis Cases Since the 1980s
Starting in the 1980s, reports of pertussis began to rise again gradually, culminating in a peak in 2012 with 48,277 reported cases. While remaining elevated, reported cases decreased until the COVID-19 pandemic began in 2020. This resurgence is attributed to several factors:
- Improved clinical recognition of pertussis by healthcare providers, leading to more accurate cough diagnosis.
- Increased availability and utilization of laboratory diagnostics for respiratory infections.
- Enhanced surveillance and reporting mechanisms by public health departments.
- Waning immunity from acellular pertussis vaccines, which are used today and offer a safer profile but potentially less durable protection than the older whole-cell vaccines.
Keep Reading: Pertussis Cases by Year (1922-2022)
Genetic Changes in Pertussis Bacteria
Bordetella pertussis, the bacterium responsible for pertussis, undergoes continuous genetic evolution. The CDC is actively investigating the potential impact of these molecular changes on public health outcomes, including vaccine effectiveness and disease severity. Understanding these changes is crucial for refining diagnostic approaches and public health strategies.
Infants: A High-Risk Group for Severe Pertussis
Infants under one year of age face the highest risk of severe complications and mortality from pertussis due to their still-developing immune systems. This age group consistently shows the highest reported incidence rates. For cough diagnosis in infants, pertussis should be a primary consideration, especially during outbreaks or in unvaccinated populations.
The graph illustrates that infants under one year old have the highest incidence of pertussis compared to other age groups, emphasizing their vulnerability.
Keep Reading: Pertussis Incidence by Age Group and Year (1990-2022)
Pertussis Data Reporting Resources
NNDSS Data Tables
Access detailed infectious disease data tables from the NNDSS for comprehensive surveillance information.
View NNDSS infectious disease data tables.
Pertussis Surveillance Reports
Explore pertussis data, including case counts, incidence rates by state and age, DTaP vaccination history, and pertussis-related fatalities in surveillance reports. These reports and historical data are available at CDC Stacks.
These and older surveillance reports can be found at CDC Stacks.
Pertussis Case Definition
The Council of State and Territorial Epidemiologists (CSTE) has published the most recent standardized case definition for pertussis in 2020. This definition is crucial for consistent reporting and diagnostic criteria across different jurisdictions.
Additional Resources
For more detailed information, refer to the Pertussis chapter in the Manual for the Surveillance of Vaccine-Preventable Diseases, which provides in-depth guidance on surveillance practices and protocols.
Pertussis chapter of the Manual for the Surveillance of Vaccine-Preventable Diseases
