Infectious diseasesepidemiology and surveillance

Information for general practitioners

Diagnosis of pertussis (whooping cough) is often delayed as initial symptoms can be mild and the typical 'whoop' is not necessarily present, especially in adults or vaccinated children.  

To combat the current increased incidence it is important to think, test and treat pertussis early.

Think early

In Victoria there has been a 500 per cent rise in the number of notified cases of pertussis from 2005-10. 

Pertussis can be life threatening for infants under six months of age. 

People who have been vaccinated for pertussis are still at risk of contracting pertussis (vaccine effectiveness is around 85 per cent). Vaccination can prevent or reduce the severity of symptoms, making the diagnosis more difficult (e.g. lack of whoop). Vaccine immunity and natural immunity wane after six to ten years.  

Pertussis may first manifest with ‘cold’-like upper respiratory symptoms (catarrhal phase) and then progresses to a persistent cough along with any of the following symptoms: 

• cough with or without paroxysms
• post-tussive vomiting 
• apnoea 
• cyanosis 
• a ‘whoop'.

Test early

The diagnosis of pertussis can be confirmed through nucleic acid testing/PCR of nasal-pharyngeal swabs (not throat), aspirates or culture or serology. 

For children under two years of age, nucleic acid testing/PCR is preferred and can be positive up to five weeks after onset of illness. Serology is not recommended. Cultures can also be requested but may take as long as two weeks. 

For people two years and older, nucleic acid testing/PCR is also recommended. IgA serology (ideally both acute and convalescent) can also be done. Interpretation can be problematic as IgA may be elevated in vaccinated patients and patients with past infection or falsely negative when taken early in the disease course. 

Treat early

Early detection means less population infection. Patients are considered infectious for up to 21 days after onset of cough or until they have completed five days of an appropriate course of antibiotics.  

Antibiotic treatment in the catarrhal phase and early paroxysmal stages may ameliorate the disease and shorten infectivity. 

Macrolides are the treatment of choice (except Roxithromycin). Prophylaxis for contacts is recommended in special situations. For details please refer to Therapeutic Guidelines: Antibiotic Version 14 or contact the Department of Health, Communicable Diseases phone 1300 651 160. 

Pertussis is a notifiable condition and primary school and children’s services centres exclusion criteria apply. Please notify the Department of Health of all cases (including those diagnosed clinically only) within five days of diagnosis by:  fax: 1300 651 170 phone: 1300 651 160 or online.

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