Whooping Cough (Pertussis)
Whooping cough, also known as pertussis, is a highly infectious respiratory disease caused by the bacterium Bordetella pertussis. It can affect all age groups but most commonly occurs in children. In adolescents and adults the disease is usually mild, while in children less than one year of age it can be particularly severe. Whooping cough affects females more commonly than males, though the reason for this is not fully understood.
The disease is characterised by severe coughing spasms followed by a gasp for breath that sounds like a “whoop”. It is typically spread by coughing and sneezing. If the condition is severe, hospitalisation may be necessary. In rare cases, the condition can be fatal.
Whooping cough outbreaks tend to occur every three to five years. A recent epidemic of whooping cough in New Zealand started in April 2004 and continued into 2005. In 2004 alone, 3489 cases were reported. Health authorities have reported a rise in cases in the winter of 2009. Geographically, the highest rates of the disease occurred in the South Island, particularly in Southland. Age-wise, the highest rates of disease occurred in infants less than one year of age.
Vaccination against whooping cough is part of the national immunisation schedule and plays an important role in reducing the spread of the disease.
Signs and Symptoms
Whooping cough affects the upper respiratory tract, causing the lining of the air passages to become inflamed and damaged. This leads to an excess production of mucous, which in turn irritates the respiratory tract and causes the cough characteristic of this disease.
The symptoms of whooping cough usually follow a cycle that lasts for a number of weeks. There are three distinct stages:
First stage (Catarrhal stage): lasting 1-2 weeks:
- Loss of appetite
- Slight fever
- Watery, running nose and eyes
- Fatigue
- Sneezing
- Irritating cough (particularly at night)
Symptoms experienced during this stage often resemble those of a common cold or mild bronchitis.
Second stage (Paroxysmal stage): usually lasting 1-6 weeks, but can continue for up to 10 weeks:
- Severe coughing spasms
- A high-pitched "whooping" sound when inhaling after a coughing spasm (the “whoop” sound may not occur with young infants)
- Vomiting or turning blue due to severe coughing or choking on mucous
The coughing spasms characteristic of this stage may be triggered by such things as crying, feeding, overactivity or tobacco smoke. Where possible it is important to avoid exposure to potential triggers in order to reduce the frequency of coughing spasms.
Third stage (Convalescent stage): may last for months:
- During this stage symptoms subside, though subsequent respiratory infections, even months after the initial whooping cough infection, can cause a recurrence of the coughing spasms.
Transmission and Incubation Period
The whooping cough bacteria are spread from person to person in airborne droplets or by direct contact with infected throat or nasal discharges. Coughing and sneezing are the most common modes of transmission.
Once infection with the whooping cough bacteria has occurred, the time until symptoms appear (incubation period) is usually between five to 10 days, though it can be as long as 21 days.
The contagious period is from seven days following infection with the whooping cough bacteria, to up to one month after the appearance of the coughing spasms, with the most contagious period being during the catarrhal stage.
If there is an outbreak of whooping cough it is advisable to keep uninfected children (especially those who are unimmunised) away from the source of the infection until after the contagious period has passed. Likewise, children with whooping cough should be removed from school or daycare until they are no longer infectious
Diagnosis
Diagnosis of whooping cough will involve an assessment of the nature and history of the symptoms experienced. The disease can be difficult to diagnose in its early stages because of its resemblance to a common cold or bronchitis. As the whooping cough bacteria can be detected in respiratory secretions, nose and throat swabs may be taken to confirm the diagnosis. A chest x-ray and blood tests may also be performed.
As whooping cough is a notifiable disease, the doctor who diagnoses it is required to notify a Medical Officer of Health.
Treatment
Antibiotics are used in the treatment of whooping cough. They are most effective in reducing the severity of whooping cough when given in the very early stages of the disease. Antibiotic treatment commenced once the disease is well established, may still be recommended in order to reduce the likelihood of the bacteria spreading.
Antibiotics may also be prescribed to treat any secondary infections that may have developed. Prophylactic (preventative) antibiotic treatment may be recommended for other members of the household to prevent the spread of the disease in the community.
Further treatment of whooping cough is supportive and involves making the child comfortable. This should include:
- Bed rest
- Small frequent meals
- Maintaining fluid intake
Use of a humidifier to warm and moisten the air may be helpful in soothing the airways and reducing coughing spasms. Sitting with the child in a steamy bathroom can also be effective.
Cough suppressant medicines are not effective in treating whooping cough.
In particularly severe cases of whooping cough, treatment in hospital may be necessary. This is most commonly required in infants under six months of age, with approximately 75% of those affected in this age group requiring hospitalisation.
Treatment in hospital may include:
- Administering oxygen
- Suctioning secretions and mucous
- Administering fluids through a drip in the hand or arm in order to prevent dehydration
- Monitoring for signs of complications
- Isolation from other children to prevent the spread of the disease
Complications
Complications of whooping cough can include:
- Dehydration
- Pneumonia
- Middle ear infections
- Temporary cessation of breathing (apnoea)
- Hernias (commonly in the groin) caused by excessive coughing
- Encephalopathy (disruption in brain function) eg: swelling, damage, seizures
It is important to watch for any signs of complications. A doctor should be consulted immediately if complications are suspected.
Prevention
To prevent the spread of the disease, immunisation is essential. Immunisation against whooping cough is given as part of the national immunisation schedule. The whooping cough vaccine is given (in combination with vaccines against other diseases) at six weeks, three months, five months, 15 months and four years of age.
An acellular vaccine for whooping cough was introduced to New Zealand in 2000. This type of vaccine has fewer side effects than the whole-cell vaccines previously used. The acellular vaccine currently publicly funded for use in the New Zealand immunisation schedule is known as DTaP-IPV (Infanrix™-IPV),
A publicly funded combination vaccine for adults is also available. While whooping cough is not commonly recognised in adults, the vaccine is designed to prevent the inadvertent transmission of the virus to infants, who are at greatest risk. A GP clinic or immunisation centre can give advice as to when this vaccination is required.
Further Information and Support
For further information about immunisations consult your GP or practice nurse, or contact the following:
Immunisation Advisory Centre
For further information and support about whooping cough consult your GP or practice nurse, or contact the following:
Plunketline:
Freephone: 0800 933 922
Healthline:
Freephone: 0800 611 116
References
Everybody (2004) Whooping cough (Pertussis). Auckland: CMPMedica (NZ) Ltd. –
http://www.everybody.co.nz/page-69b491b4-0d00-441c-a03e-62ba91cf9146.aspx
Institute of Environmental Science and Research Ltd (ESR) (2006) Public Health Surveillance – 2006 Monthly Surveillance Report. Wellington.http://www.surv.esr.cri.nz/surveillance/monthly_
surveillance.php
Immunisation Advisory Centre (2004) Pertussis. Immunisation Advisory Centre (IMAC) University of Auckland
http://www.immune.org.nz/?t=641 frame .htm
Last Reviewed 5/11/06