About Pertussis Outbreaks

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Pertussis (whooping cough) is a common (endemic) disease in the United States, with peaks in reported disease every few years and frequent outbreaks. In 2012, the most recent peak year, states reported 48,277 cases of pertussis — and many more cases go unreported. The primary goal of pertussis outbreak control efforts is to decrease morbidity (amount of disease) and mortality (death) among babies; a secondary goal is to decrease morbidity among people of all ages.

Identifying Pertussis Outbreaks

Pertussis outbreaks can be difficult to identify and manage. Other respiratory pathogens (germs) often cause symptoms similar to pertussis. Also, pertussis does co-circulate with other pathogens (bacterial and viral) at times. Healthcare professionals commonly use polymerase chain reaction (PCR) tests to diagnose pertussis. PCR tests vary in their ability to correctly show who does not have pertussis (specificity). This is important because if a test has a high specificity and someone tests positive, then it is very likely they actually have the disease. Since PCR tests vary in specificity, CDC recommends getting confirmation with culture (a lab test where the bacteria are grown) for at least one suspected case any time there is suspicion of a pertussis outbreak. False (pseudo) outbreaks of pertussis have resulted because of false positive test results with PCR. This highlights the importance of recognizing clinical signs and symptoms and practicing careful laboratory testing.

Protecting Babies during Pertussis Outbreaks

To reduce the risk of pertussis in new mothers and their young babies, CDC recommends that pregnant women receive Tdap vaccine during each pregnancy.  The recommended time to get the shot is the 27th through 36th week of pregnancy, preferably during the earlier part of this time period.  During outbreaks, prevention efforts should focus on improving rates of Tdap vaccination among pregnant women to reduce serious illness and possible deaths in vulnerable babies.

Using Antibiotics during Pertussis Outbreaks

More cases of pertussis are occurring and spreading through communities. Therefore, it may not be effective for health departments to spend a lot of time and resources looking for those exposed to pertussis (extensive contact tracing) and providing them with antibiotics to help prevent further pertussis infection (post exposure antimicrobial prophylaxis, or PEP). Antibiotics may prevent pertussis disease if given before symptoms begin. However, there are no data showing that widespread use of PEP among contacts of people with pertussis works well to control or limit the size of pertussis outbreaks. Another important consideration is the overuse of antibiotics. CDC is engaged in actively promoting the appropriate use of antibiotics among healthcare professionals and patients. Given these considerations, CDC supports targeting PEP to people at high risk of developing a serious case of pertussis and to people who will have close contact with those at high risk of developing a serious case of pertussis, such as young babies. See PEP guidance.

Active Screening during Pertussis Outbreaks

Public health officials may consider active screening for symptomatic patients with suspected pertussis during outbreaks in settings such as schools, day care centers, and hospitals. Active screening for suspected cases potentially:

• Reduces exposure to people with pertussis
• Encourages timely medical evaluation and treatment of cases
• Promotes prompt administration of antibiotics to high-risk close contacts

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