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Pertussis is a highly contagious infection caused by the gram-negative bacteria Bordetella pertussis, which results in fits of coughing that usually end in a prolonged, high-pitched, deeply indrawn breath (the whoop).
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Pertussis usually affects children and adolescents.
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Mild coldlike symptoms are followed by severe coughing fits, then gradual recovery.
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The diagnosis is based on the characteristic whoop-sounding cough and examination of the mucus in the nose and throat.
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Most children with pertussis recover slowly but completely.
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Vaccination can help prevent this infection.
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Very ill children usually are hospitalized and given antibiotics to eliminate the infection.
(See also Overview of Bacteria.)
Pertussis, once rampant in the United States, is now better controlled although not eradicated. In 2016, there were almost 18,000 cases of pertussis in the United States. Local epidemics among unimmunized people occur every 3 to 5 years.
Pertussis remains a major problem throughout the developing world.
Pertussis is becoming more common even though it can be prevented by a vaccine. This increase may result from
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Wearing off of immunity in people who have been vaccinated
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Some parents refusing to allow their children to be vaccinated
Before vaccines were widely used, pertussis was a disease of young children. Now, people may develop pertussis at any age. Over half of cases occur in adolescents and adults. However, pertussis is most serious in children younger than 2 years, and nearly all deaths occur in children younger than 1 year. Most deaths are caused by pneumonia and complications affecting the brain. Pertussis is also serious in older people.
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.
Symptoms
The illness begins about 1 or 2 weeks after exposure. If no
complications develop, pertussis lasts about 6 to 10 weeks, progressing
through three stages:
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Mild coldlike symptoms
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Severe coughing fits
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Gradual recovery
Coldlike symptoms include sneezing, runny nose, loss of appetite, listlessness, a hacking cough at night, and a general feeling of illness (malaise). People may be hoarse but rarely have a fever.
Coughing fits develop after 10 or 14 days. These fits typically consist of 5 or more rapidly consecutive forceful coughs, often followed by the whoop (a prolonged, high-pitched, deeply indrawn breath). Only about half of people have typical whooping. Vaccinated children may be less likely to have whooping. 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.
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About one fourth of children develop pneumonia, resulting in difficulty breathing. Ear infections (otitis media) also frequently develop. Rarely, pertussis affects the brain in infants. Bleeding, swelling, and/or inflammation of the brain may cause seizures, confusion, brain damage, and intellectual disability. Seizures are common among infants but rare in older children.
After several weeks, the coughing fits gradually subside, but for
many weeks or even months, children may continue to have coughing fits.
Most children with pertussis recover completely, although slowly. But a few children under 1 year old die.
Diagnosis
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Culture of a sample of mucus
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Sometimes other tests on a mucus sample
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. In people with pertussis,
culture results are usually positive during the first two stages of
illness but often are negative after several weeks of illness. Results
from culture may take up to 7 days.
Polymerase chain reaction (PCR) testing, done on samples from the
nose or throat, is the most useful test. It increases the amount of the
bacteria's DNA so that the bacteria can be detected more quickly and
identified more easily.
Prevention
Children are routinely vaccinated against pertussis. The pertussis vaccine
is usually combined with vaccines for diphtheria and tetanus as DTaP
for children under 7 years and Tdap for adolescents and adults (see
Figure: Routine Vaccinations for Infants and Children). Immunity from the vaccine tends to decrease 5 to 10 years after the last dose is given.
Experts recommend a single booster dose of Tdap for adolescents
and for all adults after age 19 (including those over 65). A booster is
also recommended during each pregnancy.
After exposure to pertussis
Antibiotics are given to certain groups of people after they have
been exposed to a person with pertussis—whether they have been
vaccinated or not. These antibiotics (called postexposure antibiotics)
are given within 21 days after the person with pertussis first developed
a cough to the following :
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Household contacts (people who live in the same housing unit) of a person who has pertussis
Postexposure antibiotics are also given to certain other high-risk people who were exposed to a person with pertussis:
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Infants under 12 months old
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Women in the 3rd trimester of pregnancy
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All people with health conditions that might be made worse by pertussis (such as moderate to severe asthma, chronic lung disease, or disorders that weaken the immune system)
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People who have close contact with infants under 12 months old, with pregnant women, or with people with conditions that may result in severe illness or complications if they were infected
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All people in settings that include infants under 12 months old or women in the 3rd trimester of pregnancy (as occurs in child care centers, maternity wards, and neonatal intensive care units)
The antibiotic erythromycin (or sometimes clarithromycin or azithromycin) is given as a preventive measure. For infants under 1 month old, azithromycin is preferred.
If children under 7 years have received fewer than four doses of
vaccine and they have close contact with someone who has pertussis, they
should also be vaccinated.
Treatment
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For seriously ill infants, hospitalization and isolation
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Antibiotics
Seriously ill infants are usually hospitalized because their breathing may become so difficult that they require mechanical ventilation
through a tube placed in their windpipe. Some may need to have mucus
suctioned from their throat. Others may need extra oxygen and fluids
given by vein. Seriously ill infants are usually kept in isolation (to
prevent other people from being exposed to infected droplets in the
air—called respiratory isolation) until antibiotics have been given for 5
days. Because any disturbance can trigger a coughing fit, these infants
are kept in a darkened, quiet room and disturbed as little as possible.
Older children who have mild disease are treated with antibiotics
at home. Children treated at home should be isolated for at least 4
weeks after symptoms began and until symptoms resolve.
Cough medicines are of questionable value and are not usually used.
The antibiotic erythromycin or azithromycin, taken by mouth, is usually used to eradicate the bacteria causing pertussis.
Antibiotics are also used to treat infections that accompany the pertussis, such as pneumonia and ear infection.
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