It starts like the common cold: You have a runny nose and a slight fever. After a few days, the coughing starts—and it seems like it will never stop. The Chinese call it ‘the cough of 100 days.’

Pertussis, also known as whooping cough, is a highly contagious upper respiratory infection marked by severe coughing spasms that continue intermittently for weeks. The spasms can be so violent that they cause vomiting. “I even had one patient who herniated a disc during a coughing fit,” says Dr. Gina Marusic, a pediatrician with SSM Pediatrics at Sunset Hills.

Pertussis outbreaks occur periodically, and there currently seem to be more cases than usual in the St. Louis area, Marusic says. “We get a couple of calls a week from parents who are concerned because their child’s school has a reported case,” she says. Children who share a classroom or close contact with an infected classmate may be exposed, although children in other classes who don’t have any interactions with the sick child are unlikely to be infected.

“The danger group for developing severe disease from pertussis is children less than a year old,” says Dr. Dennis O’Connor, a pediatric infectious disease specialist with Saint Louis University and SSM Cardinal Glennon Children’s Medical Center.

The pertussis vaccine is typically administered as part of the DTaP combination vaccine, which also protects against tetanus and diphtheria. The U.S. Centers for Disease Control and Prevention recommend the vaccine at ages 2, 4 and 6 months, between 15 and 18 months, and again between 4 to 6 years of age. A booster is recommended between the ages of 10 and 12.

“Most older children, teens and adults who get whooping cough were vaccinated earlier in their life and end up with a milder case, as a result,” O’Connor says. “The whooping sound that’s characteristic of pertussis occurs when the coughing paroxysm lasts for a while and the patient finally takes a deep, whooping inhale. However, you don’t hear this sound in all cases, and babies aren’t strong enough to do it.”

Marusic says, “Just like the immunization, the immunity one develops from actually having the pertussis illness eventually wanes. You cannot get lifelong immunity from the pertussis illness or the pertussis immunization.”

For this reason, Marusic says, it’s important to continue to receive the pertussis booster “regardless if you have the illness, in order to have the best protection against the disease and help prevent the spread of pertussis to infants,” she notes.

Treatment usually involves a course of antibiotics, although by the time the disease is diagnosed, the medication may not change the length or severity of the disease. It may, however, help prevent the spread of infection to others.

“If you have a child who has pertussis, and your other children begin to develop cold-like symptoms, starting the treatment right away may help decrease the severity,” O’Connor notes, adding that any cough that lasts two weeks should be evaluated by a physician.