Whooping cough (pertussis)

Whooping cough is a severe, long-lasting respiratory disease caused by the pertussis bacterium (Bordetella pertussis). The nose, throat, trachea and lungs are affected. A hallmark of whooping cough is severe, spasmodic coughing fits that can lead to choking or, in one percent of cases, even death. During the attacks, wheezing sounds are usually heard when breathing in.

Whooping cough is a highly contagious disease. In addition, secondary diseases such as pneumonia and middle ear infections often occur. The infection is particularly dangerous for small children under six months of age, as sudden respiratory arrest can occur.

Since nowadays many people do without a vaccination or a vaccination booster against whooping cough, the number of cases is on the rise again. In the years 2002 to 2006, for example, approximately 13,000 cases were recorded in the new federal states of Germany. At the beginning of the 1980s, half of all whooping cough patients were under one year of age; between 2001 and 2004, adults over 20 years of age accounted for 60 percent of all cases. The increasing rate of adult patients is due to the fact that the vaccination only provides protection for about four to twelve years and that a booster is often not given.

Children and adults with whooping cough infection should stay at home during the contagious phase of the disease, as the high infection potential could endanger numerous other people.

Whooping cough is triggered by the bacterium Bordetella pertussis. The route of transmission is droplet infection, which means that germs enter the air when affected patients cough, sneeze or speak. At a distance of up to one metre, other people can breathe in these germs and also fall ill with pertussis.

Bordetella pertussis releases various proteins, some of which are responsible for the symptoms of the disease as toxins. Other proteins ensure that the bacteria adhere well to the upper skin layers of the respiratory mucous membranes and can multiply there.

Whooping cough-like symptoms can also be caused by bacteria of the species Bordetella parapertussis, but an infection with this pathogen is usually shorter and more harmless.

Whooping cough disease progresses in three stages, each of which is accompanied by different symptoms. These stages are called stage catarrhale, stage convulsivum and stage decrementi.

• Stage catarrhale: After an incubation period of 7 to 14 days, non-specific, flu-like symptoms such as a cold, mild fever, sore throat and dry, irritating cough occur. In this phase, which lasts about one to two weeks, the affected person is already contagious.

• Stage convulsivum: In the second stage, the typical, sudden, cramp-like, strong coughing fits with the tongue sticking out occur. When inhaling, a sound similar to a whoop can be observed - the characteristic wheezing. The attacks are often accompanied by regurgitation of glassy mucus and vomiting. The coughing attacks often occur at night or are triggered by external influences such as sport or stress. In one out of four cases, serious concomitant diseases also occur, such as middle ear infections, severe weight loss, hernias or pneumonia. The convulsivum stage can last for two to four weeks.

• Stage decrementi: In the last stage, the number and severity of coughing attacks slowly decreases. Without antibiotic treatment, another six to ten weeks pass before the disease is completely over.

In adults, whooping cough is rarely accompanied by fever and tingling in the throat, unlike in children. It is also possible for the coughing to be continuous over a long period of time, rather than being confined to isolated attacks.

In adulthood, whooping cough manifests itself mostly as a long-lasting cough and is therefore often not diagnosed. When typical symptoms occur, such as violent and prolonged coughing fits, the diagnosis is easier.

In infants, the pathogen Bordetella pertussis can be easily detected by a swab of the nasal mucosa. In adolescents and adults, however, this method is not reliable and often provides false results. The genetic material of the bacteria can be reliably detected in laboratories using a polymerase chain reaction (PCR), but this is an expensive and time-consuming diagnostic technique.

In the later course of the disease - at the earliest from the convulsive stage - antibodies against specific proteins of Bordetella pertussis can be detected in the blood and thus a reliable diagnosis can be made.

In adults and older children, severe complications of pertussis are not usually expected.

Antibiotics are the treatment of choice. Although these can significantly shorten and mitigate the course of the disease only if administered in time, they prevent other people in the vicinity of the sick person from becoming infected.

The antibiotics azithromycin, clarithromycin, roxithromycin and erythromycin are recommended by the German Robert Koch Institute as the first choice in the treatment of whooping cough.

Whooping cough infection can persist for several weeks to months. If left untreated, there is a risk of infection from the onset of the first symptoms up to three weeks into the convulsive stage. Antibiotic treatment eliminates the danger within five days, but is ineffective against the cough.

Concomitant diseases occur more frequently in children than in adults. Complications such as middle ear infections or pneumonia occur in about a quarter of cases.

Effective and well-tolerated vaccines exist for primary prophylaxis. It is recommended to vaccinate children from the third day of life three times at intervals of four weeks. A fourth vaccination in the fourth year completes the basic immunization. Thereafter, booster vaccinations should be given between the ages of five and six and between nine and seventeen.

The protective effect of the vaccination against whooping cough is maintained for around ten to a maximum of twenty years. After an infection has been overcome, there is natural immunity for the next three years.

To date, there is no single vaccine for older children and adults that provides basic immunization. However, there are combination vaccines against tetanus, diphtheria, pertussis and polio that can produce an adequately high level of antibodies against Bordetella pertussis in adults. Often, only one vaccine dose is needed in adults because they have had contact with the bacterium in childhood. To provide better indirect protection for infants, parents, close relatives and other caregivers should have adequate vaccination protection. If there is a risk of infection with whooping cough, it is also recommended that close contacts of the person with the disease take preventive medication.