Pertussis, whooping cough, is a highly contagious infectious disease of the respiratory tract. It is notifiable in Austria and is caused by the bacterium Bordetella pertussis. It is possible to contract the disease several times despite having been infected and immunised, as the protective effect of the antibodies formed does not last long. Infants and young children are particularly affected by severe cases. Most deaths occur in the first year of life (approx. 1 % of those affected).

Pertussis is a widespread disease worldwide. It occurs all year round, but the number of cases is higher in autumn and winter than in the rest of the year.

Human

The transmission is a droplet infection, the pathogen is passed on through the air when coughing or sneezing. Pertussis is highly contagious, particularly in the first two weeks, and the risk of infection can last until the fifth week after the onset of the disease.

There are three stages in the initial infection of unvaccinated people:

• the catarrhal stage is characterised by cold-like symptoms such as a runny nose and cough, rarely also a slight fever (lasting between 1-2 weeks)
• the convulsive stage, which can last 4-6 weeks, is characterised by coughing attacks. During these barking, paroxysmal and spasmodic coughing attacks, the patient may choke up thick mucus and subsequently vomit
• During the decrementi stage, the coughing fits subside (lasting 6-10 weeks)

In vaccinated persons, pertussis can often manifest itself as a long-lasting cough, but without the classic accompanying symptoms mentioned above. In unvaccinated infants under 6 months of age, pneumonia and even respiratory arrest can occur.

Pertussis is treated with antibiotics. To be effective, treatment must begin as early as possible in the course of the disease. Antibiotic treatment can reduce the bacteria in the nose and throat, which also limits the risk of transmission to other people.

The best prevention against whooping cough is immunisation. It is included in the free childhood vaccination programme and must be boostered at school age. After this basic immunisation, the vaccination must also be regularly boostered in adulthood. The pertussis vaccination is recommended for everyone.

In order to protect infants in the first months of life, pregnant women in the third trimester in particular are recommended to be vaccinated (Ministry of Health: "Faktencheck: Keuchhusten. Impffen schützt!").

Pertussis cases rose steadily in Austria before the COVID-19 pandemic. There was an increase in complications in adults and long-term courses. While 579 cases were reported nationwide in 2015, there were already 2,233 in 2019. The low figures in previous years are due to the effects of the pandemic and the measures taken to contain it. In 2023, 2,791 cases were reported. 13441 cases of pertussis have been reported so far in 2024 (as of 29/10/2024).

Typical whooping cough symptoms are often present in infants and young children, whereas they are often absent in adults, older children and adolescents. In any case, laboratory diagnostics should be carried out to confirm the diagnosis. Within the first few weeks after the onset of coughing, detection of the bacterium in a nasopharyngeal swab using a PCR test and, if necessary, cultural cultivation is recommended. Serodiagnostics can be carried out later in the course of the disease.

Complications

Pertussis can lead to complications such as pneumonia, middle ear infections, loss of appetite, dehydration, seizures, neurological disorders, hernias, rib fractures, rectal prolapse and respiratory arrest. Severe cases can lead to death. Deaths occur most frequently in infants who die from pneumonia or lack of oxygen to the brain.

Pertussis can occur at any age. The number of adults and adolescents diagnosed with whooping cough is increasing. The age groups with the most pertussis diagnoses are currently infants under one year of age and adolescents between 10 and 20 years of age. All persons who have not been immunised or fully immunised against Bordetella pertussis are at risk, regardless of their age. A clinical picture similar to whooping cough can also be caused by the related pathogens Bordetella parapertussis and B. holmesii.

Choice of therapy

In addition to symptomatic therapy, macrolide antibiotics such as erythromycin, azithromycin and clarithromycin are primarily used to treat pertussis.