Cases of pertussis, or whooping cough, are on the rise across the United States.

The U.S. Centers for Disease Control and Prevention reports to date 17,579 cases of whooping cough, more than five times the number of cases reported during the same period in 2023.

To explain the disease, its symptoms and why the numbers are climbing, we turned to Teena Chopra, M.D., M.P.H., professor of Internal Medicine, Infectious Diseases, for the Wayne State University School of Medicine. Dr. Chopra serves as the corporate medical director of Hospital Epidemiology, Infection Prevention and Antibiotic Stewardship at the Detroit Medical Center, Wayne State University. One of the founding leaders of the WSU Center for Emerging and Infectious Diseases, she championed the mammoth task of leading COVID-19 pandemic efforts for Wayne State University and the DMC.

What is whooping cough? What are the symptoms?
Whooping cough is a respiratory illness caused by the bacterium Bordetella pertussis, which is exclusively found in humans. The bacteria attach to the cilia—small, hair-like structures—in the upper respiratory tract. They produce toxins that harm the cilia and lead to swelling of the airways.
Symptoms typically appear five to 10 days after exposure but can take up to three weeks. Initially resembling a common cold, early symptoms last one to two weeks and include:
•    Runny or stuffy nose
•    Low-grade fever (under 100.4°F)
•    Mild, occasional cough
Babies may struggle to breathe, and some might not cough at all but experience apnea, leading to cyanosis, a bluish discoloration of the skin, lips or nails due to a lack of oxygen. One to two weeks after the initial symptoms, coughing fits (paroxysms) develop, lasting one to six weeks, or even up to 10 weeks. Symptoms during these fits can include:
•    A high-pitched "whoop" when inhaling
•    Vomiting
•    Extreme fatigue after fits
•    Sleep difficulties
•    Breathing struggles
•    Rib fractures
Of note, symptoms of whooping cough are milder in vaccinated individuals.

How serious a disease is it? How harmful can it be?
Whooping cough can lead to severe and potentially fatal complications in infants and young children. Those who have not received all recommended vaccinations are at a higher risk for serious issues. The complications include:
•    Apnea
•    Pneumonia 
•    Convulsions 
•    Encephalopathy 
•    One in 100 (1%) may die from these complications.
For teens and adults, complications such as pneumonia can occur. However, these complications are generally less severe in this age group, particularly among those who have been vaccinated.

Who is most susceptible?
Infants younger than 1 year and underlying health issues like immunocompromising conditions or moderate to severe asthma increase the risk of severe whooping cough, making prevention essential.

Is it contagious?
Yes, individuals can spread the bacteria from the onset of symptoms and for at least two weeks after coughing starts. Early antibiotic treatment may reduce contagiousness. Some people have mild symptoms and may not realize they have whooping cough, allowing them to unknowingly infect others. Many infants contract the disease from older siblings or caregivers who are unaware they are infected.

Isn’t whooping cough a childhood disease?
Yes, whooping cough, or pertussis, is often considered a childhood disease because it primarily affects infants and young children. However, it is a misconception that it can only infect young children. It can also affect adolescents and adults. Vaccination during childhood helps prevent severe cases, but immunity can wane over time, which is why booster shots are recommended for older children, teenagers and adults.

Once you’ve had it, do you then become immune? Is there an effective vaccine against whooping cough?
Yes, vaccines are the only effective way to protect against whooping cough. The U.S. Centers for Disease Control and Prevention advises that everyone receive the whooping cough (pertussis) vaccine. These vaccines are the most effective way to guard against whooping cough. While they are effective, immunity can decrease over time. If you have any questions about whooping cough vaccinations, consult a vaccine provider.

Can pregnant women be inoculated, and will that pass on to their babies?
Yes, the CDC recommends pregnant individuals receive the Tdap vaccine between the 27th and 36th week of pregnancy, preferably earlier in this period. This timing ensures that protective antibodies peak about two weeks after vaccination and can be effectively transferred to the baby. Since antibody levels decrease over time, getting vaccinated early in the third trimester—even if pregnancies are close together—provides the best protection against whooping cough for each baby.

Why are cases in the United States on the rise?
The rise in whooping cough cases indicates we're returning to pre-pandemic levels. Several theories explain this uptick: One is that the safety measures implemented during the pandemic—like masking and social distancing—not only reduced the spread of COVID-19 but also curtailed the transmission of other respiratory viruses, including whooping cough. Additionally, low vaccination rates, waning vaccine immunity over time, advancements in testing for whooping cough and greater awareness of outbreaks in our communities may also contribute to the increase.

Is there a test to distinguish whooping cough from other seasonal infections?
Whooping cough can be hard to diagnose because its symptoms are similar to other respiratory illnesses. Knowing if you've been in contact with someone with whooping cough can help.
Diagnosis typically involves:
•    Reviewing symptoms
•    A physical exam
•    A mucus sample test
•    A blood test

How is it treated by physicians?
It's crucial to address whooping cough promptly, ideally before the onset of coughing fits. Health care professionals typically manage the condition with antibiotics. If symptoms are severe, additional treatment in a hospital may be necessary.