Whooping cough
A young child in a hospital bed gasps for air after a violent coughing fit. The sound that follows is not just a wheeze but a high-pitched whoop, the signature of Bordetella pertussis infection. This disease earns its nickname the 100-day cough because severe fits can last ten weeks or more. Initial symptoms mimic a common cold with a runny nose and mild fever. Yet within two to three weeks, the illness shifts into uncontrollable paroxysms. These violent episodes often end with vomiting or fainting. Rib fractures occur frequently enough to be documented as a direct physical consequence of the strain on the chest wall. In infants under one year old, the classic whoop may never appear. Instead they face periods where breathing simply stops.
Bordetella pertussis spreads through tiny droplets released when an infected person coughs or sneezes. Once inside the nasopharynx, surface proteins like filamentous hemagglutinin help the bacteria attach to ciliated epithelial cells. They multiply rapidly before spreading down into the lungs of vulnerable infants. A specific toxin called tracheal cytotoxin kills these airway cells. Without them, mucus and debris cannot clear from the throat naturally. Another secretion known as pertussis toxin causes lymphocytosis by raising white blood cell counts. Elevated white blood cells contribute to pulmonary hypertension which is a major cause of death in severe cases. The bacteria effectively suppress the immune system allowing infection to persist unchecked.
Physicians rely on overall clinical impressions rather than single factors to make initial diagnoses. Vomiting after coughing or hearing a whoop supports the diagnosis in adults with symptoms lasting less than eight weeks. Laboratory confirmation requires collecting samples from the back of the nose and throat. Culturing these samples on Bordet-Gengou medium works only during the first three weeks of illness. Polymerase chain reaction testing offers limited usefulness for an additional three weeks beyond that window. Direct fluorescent antibody methods become useless after the third week as well. Serology tests measure antibodies against pertussis toxin in the blood of those infected for several weeks. These blood tests determine if high levels of immunity exist against virulence factors produced by B. pertussis.
The World Health Organization recommends routine immunization starting between six and eight weeks of age. Four doses are typically given within the first two years of life. Protection decreases over time so booster doses are often recommended for older children and adults. A 2011 study indicated protection may last only three to six years covering childhood which is the period of greatest risk. The multi-component acellular vaccine ranges from 71 to 85 percent effective against severe strains. Despite widespread vaccination campaigns, infections persist in vaccinated populations. The resurgence in the 21st century stems from waning immunity combined with bacterial mutations. Adolescents and adults now act as reservoirs infecting infants who have received fewer than three doses.
Erythromycin clarithromycin azithromycin or trimethoprim-sulfamethoxazole serve as standard antibiotic treatments. Newer macrolides are frequently chosen due to lower rates of side effects. Guidelines suggest treating people over one year old within three weeks of cough onset. Infants under one year and pregnant women should receive treatment within six weeks of symptom onset. If diagnosis occurs late antibiotics will not alter the course of illness. Even without medication patients stop spreading pertussis after the infectious period ends. Short-term courses like azithromycin for three to five days prove as effective as longer regimens. Over-the-counter cough medications offer no benefit and are discouraged by medical authorities.
An estimated 16.3 million people worldwide were infected in 2015 alone. Most cases occur in developing nations where surveillance systems often miss data. In that same year pertussis resulted in 58,700 deaths down from 138,000 in 1990. A 2017 study estimated a global burden of 24 million cases annually with 160,000 child deaths. About 90 percent of all cases happen in developing countries. More than 151,000 cases were reported globally in 2018 though many remain unreported. Epidemics cycle every three to five years regardless of vaccination status. Herd immunity declines over time allowing new epidemics to emerge once thresholds drop below critical levels.
Jules Bordet and Octave Gengou discovered the bacterium in 1906 at the Pasteur Institute. They successfully cultured B. pertussis and developed the first inactivated whole-cell vaccine in 1912. Louis W. Sauer created another vaccine for whooping cough at Evanston Hospital during the 1920s. Thorvald Madsen tested a whole-cell vaccine on a wide scale in the Faroe Islands in 1925. Two children died shortly after receiving that early version. Leila Denmark began her study of the disease following an outbreak in Atlanta Georgia in 1932. She partnered with Emory University and Eli Lilly & Company to develop the first safe and effective pertussis vaccine. Grace Eldering Loney Gordon and Pearl Kendrick combined this with diphtheria and tetanus toxoids in 1942. Yuji Sato later developed an acellular vaccine used in Japan starting in 1981.
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Common questions
What causes the disease known as whooping cough?
Whooping cough is caused by the bacteria Bordetella pertussis. This bacterium spreads through tiny droplets released when an infected person coughs or sneezes.
How long does the illness called whooping cough last?
The 100-day cough earns its nickname because severe fits can last ten weeks or more. Initial symptoms mimic a common cold before shifting into uncontrollable paroxysms within two to three weeks.
When was the first vaccine for whooping cough developed?
Jules Bordet and Octave Gengou developed the first inactivated whole-cell vaccine in 1912 at the Pasteur Institute. Leila Denmark later partnered with Emory University and Eli Lilly & Company to develop the first safe and effective pertussis vaccine following an outbreak in Atlanta Georgia in 1932.
Why do infants under one year old face higher risks from whooping cough?
Infants under one year old may never show the classic whoop and instead face periods where breathing simply stops. They are also vulnerable to rib fractures and pulmonary hypertension which is a major cause of death in severe cases.
What antibiotics treat infections caused by Bordetella pertussis?
Erythromycin clarithromycin azithromycin or trimethoprim-sulfamethoxazole serve as standard antibiotic treatments. Newer macrolides are frequently chosen due to lower rates of side effects.