Pertussis fact sheet

What is pertussis?

Pertussis, also known as whooping cough, is a highly infectious bacterial disease involving the respiratory tract. It is caused by a bacterium (Bordetella pertussis) that is found in the mouth, nose and throat of an infected person.

Who gets pertussis?
Pertussis can occur at any age. Although most of the reported cases occur in children under five years, the number of cases in adolescents and adults is increasing.

Where does pertussis occur?
About 20-40 million cases of pertussis occur worldwide each year, 90% of which occur in developing countries. Of these some 200-400,000, mostly infants, die from the disease.

How is pertussis spread?
Pertussis is primarily spread by direct contact with discharges from the nose and throat of infected individuals. Frequently, older siblings who may be harboring the bacteria in their nose and throat can bring the disease home and infect an infant in the household.

What can be done to limit the spread of pertussis? An individual with pertussis can be infectious for four to five weeks from the onset of the illness. Treatment of cases with certain antibiotics such as erythromycin can shorten the contagious period by stopping the risk of infection to other people. However, it does nothing to shorten the length of the illness and the cough. People who have or may have pertussis should stay away from young children and infants until properly treated. Treatment of people who are close contacts of pertussis cases is also an important part of prevention.

What are the symptoms of pertussis?
Symptoms usually appear after 7-10 days of infection, but may also appear up to 21 days later. Initially, symptoms resemble those of a common cold, including sneezing, runny nose, low-grade fever and a mild cough. Within two weeks, the cough becomes more severe and is characterized by episodes of numerous rapid coughs followed by a crowing or high-pitched whoop. These episodes frequently end with the expulsion of a thick, clear mucous, often followed by vomiting. They initially occur at night and then become more frequent during the day and may recur for one to two months. In young infants the typical 'whoop' may never develop and coughing spasms may be followed by periods of apnoea (episodes of cessation of breathing). Older people or partially immunized children generally have milder symptoms. Prolonged immunity to the bacterium is attained following infection.

What are the complications associated with pertussis?
Complications of pertussis may include pneumonia, middle ear infection, loss of appetite, dehydration, seizures, encephalopathy (disorders of the brain), apneic episodes (brief cessation of breathing) and death.

How can pertussis be prevented?
The most important way to prevent pertussis is through complete immunization. The vaccine for pertussis is usually given in combination with diphtheria and tetanus. A primary course of three doses of DTaP (diphtheria, tetanus, acellular pertussis) vaccine or DTwP (diphtheria, tetanus, whole cell pertussis) vaccine is usually given between two and six months of age. A second dose is usually recommended at 11-18 months of age and final dose between three and six years of age. However, there is considerable variation between different national immunization schedules in the timing of these doses.

Is the pertussis vaccine safe?
Yes. The vaccines that protect against pertussis are generally safe with few minor adverse reactions such as local redness and swelling. Reactions such as fever drowsiness, agitation and loss of appetite may also occur. Most of these problems resolve by themselves. Less frequently, high fever, persistent inconsolable crying lasting more than three hours, fainting or an unresponsive collapsed-like state, and convulsions can occur. Most of these events have no long-term consequences. Very rarely, severe nervous system problems have been reported. In recent years, some countries have replaced the whole-cell type of pertussis vaccine with the acellular type as this is associated with fewer side effects.

Note: The information presented by this fact sheet is intended to supplement, not substitute for, the expertise and judgement of healthcare professionals.
Updated: 1 December 2006