Chances are, you think you have never had whooping cough, the bacterial infection known medically as pertussis. Chances are, you’re wrong.
Children get five doses of the DTaP vaccine against diphtheria, pertussis and tetanus before entering school. But even with widespread vaccination, “almost everyone has had pertussis,” Dr. James D. Cherry, an expert in whooping cough, told me. “Mild illness is almost always overlooked. More than 90 percent of cases don’t get recognized.”
Neither the vaccine nor the actual illness confers lifelong immunity, and every three to five years there is an epidemic of this disease in the United States. One is occurring now, and it could turn out to be the largest reported outbreak of pertussis in 50 years, according to the Centers for Disease Control and Prevention.
Dr. Cherry, a professor of pediatrics at the University of California, Los Angeles, explained that in a person who has had the disease or been immunized for it, its symptoms — a runny or stuffy nose, little or no fever and a cough — typically resemble those of a common cold. Most people weather it without ever going to the doctor.
Pertussis is highly contagious, spreading from person to person through coughs and sneezes. If someone with the infection comes in contact with an unprotected infant, the result can be catastrophic. Babies who are not fully immunized may develop pneumonia, severe breathing problems and terrifying seizures; they may even die from pertussis. More than half of the babies who get it must be hospitalized, the C.D.C. reports.
Currently, the vaccine is administered at ages 2, 4 and 6 months, and again at 15 to 18 months and at 4 to 6 years. In 2005, DTaP replaced the old “whole cell” pertussis vaccine, called DTP, which often caused severe side effects, including high fevers, seizures, uncontrollable crying and floppiness. Although the old vaccine was blamed for some cases of sudden infant death, this turned out to not be the case, Dr. Cherry said.
In 2010, 27,550 cases of whooping cough were reported to the C.D.C., which estimates that 10 times as many infections actually occurred but were not recognized or not reported. By the end of August of this year, more than 25,000 cases were reported, including 13 deaths, most in children younger than 1.