Colds and flu

Updated 05 October 2017

Diagnosing flu

The diagnosis of flu is based on the analysis of symptoms by a doctor. Indications are a high temperature, chills, body aches and fatigue.


The first step in the diagnosis of influenza is a clinical suspicion. You or your general practitioner may suspect flu based on your symptoms and the occurrence of the illness in the community.

Although flu can only be confirmed through laboratory testing, your doctor will usually make the diagnosis based on the severity of your symptoms. A high temperature, chills, body aches and significant fatigue are indications that you may have the flu.

Read: Flu is transmitted before symptoms appear

Should your doctor choose to send a sample for laboratory testing, a swab will be taken from the throat or nose.

Influenza infection can only be confirmed by a laboratory test: throat and/or nasal swabs are taken and the virus is grown in cell culture. After the virus has multiplied in culture, it can be detected in many ways, for instance by adding red blood cells or using a fluorescence microscope.

Read more:
What is flu?
Flu and smokers

Summer flu?


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Flu expert

Dr Heidi van Deventer completed her MBChB (Bachelor of Medicine and Bachelor of Surgery) degree in 2004 at the University of Stellenbosch.
She has additional training in ACLS (Advanced Cardiac Life Support) and PALS (Paediatric Advanced Life Support) as well as biostatistics and epidemiology.

Dr Van Deventer is currently working as a researcher at the Desmond Tutu Tuberculosis Centre at the University of Stellenbosch.

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