Pertussis (Whooping Cough)

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 that is found in the mouth, nose and throat of an infected person. Pertussis is a notifiable disease. 

Would you know pertussis?
Hear the cough of a child or adult (courtesy of CDC, US)

Video of adult with characteristic "whooping" cough (courtesy of NEJM)

Who gets pertussis?
Pertussis can occur at any age. Although most reported cases occur in children less than five years, cases are reported amongst adolescents and adults every year.  

Where does pertussis occur?
Pertussis occurs world-wide. The disease is an important cause of infant death internationally and continues to be a public health concern even in countries with high vaccination coverage. Estimates from WHO suggest that, in 2008, about 16 million cases of pertussis occurred worldwide, 95% of which were in developing countries, and that about 195 000 children died from the disease.

In recent years in Ireland we have seen an increased number of cases among infants, some of whom are too young to have received the three primary doses of vaccine necessary to provide protection. Pertussis outbreaks have been reported from both community and school settings.

How is pertussis spread?
Pertussis is primarily spread by direct contact with discharges from the nose and throat of infected individuals. Infection is often transmitted to young children in the home from older siblings or adults who may be harbouring the bacteria in their nose and throat.  

What can be done to limit the spread of pertussis?
Immunisation is the most effective way to prevent infection and limit the spread of pertussis. Children who are unimmunised, or partially immunised, should be vaccinated according to national guidelines (see section below - "How can pertussis be prevented?").

Once infected, an individual with pertussis can be infectious for four to five weeks from the onset of the illness. Greatest infectivity occurs early on in the illness, even before the cough has developed. Thus, infected individuals can transmit the infection before they know they have pertussis.  

Treatment of cases with certain antibiotics such as erythromycin, clarithromycin, or azithromycin 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 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). Young children (particularly infants) are most severely affected by pertussis. Older people and partially immunized children generally have milder symptoms. Prolonged immunity to the bacterium is attained following infection.   

What are the complications associated with pertussis?
About 20% of cases may require hospitalisation for complications of the illness. Complications of pertussis may include pneumonia (1 in 20), middle ear infection, loss of appetite, dehydration, seizures and encephalopathy (approximately 1% and 0.1% respectively), apnoeic episodes (brief cessation of breathing) and death (0.2%).

How can pertussis be prevented?
The most important way to prevent pertussis is by immunisation. Currently in Ireland, the vaccine for pertussis is usually given as part of the "6-in-1" vaccine. This vaccine protects against pertussis, diphtheria, tetanus, Haemophilus influenzae type b, hepatitis B and polio. Three doses of the "6-in-1" vaccine are usually given at two, four and six months of age. A fourth dose is recommended at 4-5 years. In the past, before the introduction of the "6-in-1" vaccine, DTP vaccine was used to protect against pertussis. A further booster, using Tdap which contains lowdose acellular pertussis vaccine, is recommended at 11-14 years.

Pertussis vaccination should be considered for children aged less than 10 years who are exposed to pertussis, if they have received fewer than 4 doses of the vaccine. Children may be given dose four as early as 12 months of age, preferably 6 months after dose three. 

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. Fever and irritability can occur, however high temperature is rare. More serious side-effects, such as prolonged inconsolable crying or, fainting or an unresponsive collapsed-like state, and convulsions are rarely reported. Most of these events have no long-term consequences. Very rarely, severe nervous system problems have been reported. 

If your child requires vaccination, or you are unsure of your child's vaccination status, contact your GP for advice.

Last updated: 14 August 2012