Infection at first causes a runny nose, sore throat, and mild cough. But later, the cough can turn vicious. The babies cough spasmodically, then whoop as they try to catch their breath. They may vomit or turn purple. If the brain is deprived of oxygen, babies may suffer seizures or develop permanent brain damage.
Some infected infants die.
Pertussis is less likely to be fatal in older children, but they occasionally develop ear infections or pneumonia. Most U.S. infants receive their first dose of the pertussis vaccine at age 2 months. The disease remains a threat, however, especially for younger infants and children who have not been vaccinated. Since the 1980s, pertussis infection in the United States has surged cyclically, with peaks every 3 to 4 years. The last upsurge occurred in 1993.