Pertussis (whooping cough)

Pertussis, also known as whooping cough, is a highly contagious bacterial infection that usually causes mild respiratory infections. It is most dangerous in infants and is a significant cause of complications and death in this age group. Epidemics of pertussis occur in communities with low immunization coverage.

Whooping cough is an important cause of morbidity and mortality in infants worldwide. Periodic large outbreaks of the infections occur with an inter-epidemic cycle of two to five years. In 2018, there were more than 151,000 cases of pertussis globally (data from WHO).

The following are standard case definitions to allow national health authorities to interpret data in an international context. However, during an outbreak case definitions may be adapted to the local context and the Red Cross Red Crescent should use those agreed/established by national health authorities. NB: Consider that during community surveillance, volunteers should use broad (simplified) case definitions to recognize most or all possible cases and encourage them to seek care. Other actors such as healthcare workers or investigators studying the cause of a disease, on the other hand, can use more specific case definitions that may require laboratory confirmation.

Clinical case definition

A case diagnosed as pertussis by a physician OR a person with a cough lasting at least two weeks with at least one of the following symptoms: paroxysms (i.e. fits) of coughing, inspiratory whooping (i.e. ”whooping” sound when breathing in), post-tussive vomiting (i.e. vomiting immediately after coughing) without other apparent cause.

 

Criteria for laboratory confirmation: Isolation of Bordetella pertussis OR detection of genomic sequences by means of the polymerase chain reaction (PCR) OR positive paired serology.

WHO case definition source of information: https://www.who.int

A single case in non-endemic areas.

A cluster of pertussis cases in endemic areas.

• Unvaccinated adults, infants and children.
• Crowded settings in outbreak areas, e.g. displaced people in emergency shelters.
• Refugees, internally displaced people and migrants are at increased risk to become infected if living in crowded conditions and when missing routine immunization programmes.
• Inadequate sanitation and hygiene measures.
• Vaccine-preventable disease outbreaks can be particularly deadly in countries experiencing or recovering from a natural disaster or conflict. Damage to health infrastructure and health services interrupts routine immunization and overcrowding in residential camps greatly increases the risk of infection.

Attack rates will vary from one outbreak to another. In case of an outbreak, consult the latest information provided by health authorities.

Secondary attack rates among non-immunized household contacts are high (up to 90 per cent). Infected people are contagious up to about two weeks after the cough begins and can therefore infect many people.

• Infants.
• Unvaccinated teenagers and adults.
• Immunosuppressed persons such as those receiving chemotherapy,  transplant recipients or HIV carriers.
• People with chronic diseases such as renal disease, cancer, chronic liver or lung disease, and diabetes.

Bordetella pertussis (bacterium).

Humans.

Airborne and droplet spread: sneezing, coughing, talking can transmit Bordetella pertussis bacterium. Many babies who get pertussis are infected by older siblings, parents or caregivers who are asymptomatic and might not know they have the disease. Sharing eating and drinking utensils can increase droplet spread.

7—10 days (range 6—20 days).

Untreated patients may be contagious for three weeks or more following onset of the cough. Antibiotics may shorten the amount of time someone is contagious.

• The first symptoms of pertussis include mild fever, runny nose and cough, which in typical cases gradually develops into a paroxysmal (i.e. fits) of coughing, followed by inspiratory whooping (i.e. “whooping” sound when breathing). Coughing can occur more often at night. The cough can lead to respiratory exhaustion, vomiting and broken ribs.
• Infants can present with a cough that is minimal or that almost cannot be perceived. Infants often present with apnoeas (a pause in breathing), fever, poor feeding, convulsions. Almost 50 per cent of infants require hospital care.
• Pneumonia is a relatively common complication especially in infants. Other complications include encephalopathy, rib fractures, convulsions and loss of bladder control in adults.
• Many children who contract the infection have coughing that lasts four to eight weeks. Recovery from pertussis can happen slowly.

Influenza, parotitis due to other causes, respiratory syncytial virus (RSV) infection, COVID-19 disease, diphtheria, measles, other infections of the respiratory tract. Non-infectious diseases like exacerbated chronic respiratory diseases or allergies.

Diagnosis of pertussis is based on recovering Bordetella pertussis bacteria from nasopharyngeal mucous.

• Serological diagnosis can be helpful and is usually based on detection of a significant increase in the concentration of specific antibodies against Bordetella pertussis in paired serum samples which should be collected during the early stage (acute serum) and about one month later.
• It can also be confirmed by detection of Bordetella pertussis by polymerase chain reaction (PCR).

Please refer to the appropriate local or international guidelines for clinical management. All clinical management including the administration of any treatment or vaccine should be conducted by health professionals.

• Patient isolation is necessary.
• Pertussis is treated with antibiotics and early treatment is very important to prevent complications.
• The best way to prevent pertussis is through immunization. The World Health Organization (WHO) recommends that the first vaccine dose is administered as early as 6 weeks of age with subsequent doses given 4—8 weeks apart, at age 10—14 weeks and 14—18 weeks. Pertussis vaccines are commonly available in combination with other vaccines such as vaccines against diphtheria and tetanus. A booster is recommended, preferably during the second year of life. Based on local epidemiology, further booster doses may be warranted later in life.
• Vaccination of pregnant women is also effective at preventing disease in infants, and many countries include the DPT-3 (Diphtheria, Pertussis and Tetanus) vaccine in vaccination schedules during pregnancy.

• Natural pertussis infection does not confer long-lasting protection against pertussis. Symptomatic reinfections can occur in adolescents and adults and have also been reported in children.
• While pertussis vaccines are the most effective tool to prevent this disease, there is still a chance that fully vaccinated people can catch the disease. This may happen in contexts where the disease is circulating in the community. Nevertheless, the infection is usually less serious. The vaccine typically offers good levels of protection within the first two years after getting the vaccine, but then protection decreases over time. Pertussis vaccine booster doses are required to provide longer-lasting immunity.