Diseases & Conditions



Pertussis (whooping cough) is a highly contagious infection caused by the bacterium Bordetella pertussis , which results in fits of coughing that usually end in a prolonged, high-pitched, deeply indrawn breath (the whoop).

Pertussis, once rampant in the United States, is now better controlled although not eradicated. Local epidemics among unimmunized people occur every 2 to 4 years. Pertussis remains a major problem throughout the developing world.

People may develop pertussis at any age, but one third of cases occur in children younger than 10 years, and one third occur in adolescents 11 to 18 years of age. Pertussis is most serious in children younger than 2 years, and nearly all deaths occur in children younger than 6 months. One attack of pertussis does not always give full immunity for life, but a second attack, if it occurs, is usually mild and not always recognized as pertussis. In fact, some adults with "walking pneumonia" actually have pertussis.

An infected person spreads pertussis bacteria into the air in droplets of moisture produced by coughing. Anyone nearby may inhale these droplets and become infected. Pertussis usually is not contagious after the third week of the infection.


The illness lasts about 6 to 10 weeks, progressing through three stages: mild cold-like symptoms, severe coughing fits, and gradual recovery. Cold-like symptoms include sneezing, runny nose, a hacking cough at night, and a general feeling of illness (malaise). After 1 or 2 weeks, the person develops typical coughing fits. These fits typically consist of 5 or more rapidly consecutive forceful coughs followed by the whoop (a prolonged, high-pitched, deeply indrawn breath). After a fit, breathing is normal, but another coughing fit follows shortly thereafter. The cough often produces large amounts of thick mucus (usually swallowed by infants and children or seen as large bubbles from the nose). In younger children, vomiting often follows a prolonged fit of coughing. In infants, choking spells and pauses in breathing (apnea), possibly causing the skin to turn blue, may be more common than the whoops.

About one fourth of children develop pneumonia, resulting in difficulty breathing. Ear infections (otitis media) also frequently develop. Rarely, pertussis affects the brain of infants. Bleeding, swelling, or inflammation of the brain may cause seizures, confusion, brain damage, and mental retardation.

After several weeks, the coughing fits gradually subside, but for many weeks or even months, children have a lingering, persistent cough.

Diagnosis and Prognosis

Doctors suspect pertussis because of the typical whooping cough or other symptoms. They confirm the diagnosis by culturing a sample of mucus from the back of the nose or throat. Culture results often are negative after several weeks of illness. Other diagnostic tests (such as a polymerase chain reaction or rapid detection test) performed on samples from the nose or throat may be helpful.

Most children with pertussis recover completely, although slowly. About 1 to 2% of the children younger than 1 year die.

Prevention and Treatment

Children are routinely vaccinated against pertussis. The pertussis vaccine is usually combined with vaccines for diphtheria and tetanus (see Newborns and Infants:Vaccinations ). The antibiotic erythromycin Some Trade Names E-MYCIN ERYTHROCIN ILOSONE (or sometimes clarithromycin Some Trade Names BIAXIN or azithromycin Some Trade Names ZITHROMAX ) is given as a preventive measure to children exposed to pertussis.

Severely ill infants are usually hospitalized because their breathing difficulty may become so severe that they require mechanical ventilation through a tube placed in their windpipe. Others may need extra oxygen and intravenous fluids. Seriously ill infants are usually kept in isolation (to prevent other people from being exposed to infected droplets in the air) until antibiotics have been given for 5 days. Older children who have mild disease are treated with antibiotics at home. Cough medicines are of questionable value and are not usually used.

The antibiotic erythromycin Some Trade Names E-MYCIN ERYTHROCIN ILOSONE , clarithromycin Some Trade Names BIAXIN , or azithromycin Some Trade Names ZITHROMAX is usually used to eradicate the bacteria causing pertussis. Antibiotics are also used for infections that accompany the pertussis, such as pneumonia and ear infection.

Last full review/revision June 2006 by Geoffrey A. Weinberg, MD

Source: The Merck Manual Home Edition