When should you consult a doctor?
If you have a high fever for more than a few hours, and are not certain whether it is due to flu, it is advisable to see a health care professional for an opinion.
If your fever lasts longer than two days
If you feel sick and just don't seem to get better
If you have a cough that begins to produce phlegm
Any sign of complications of flu (see complications) should prompt a visit to a health care professional.
If you have difficulty breathing, feel a sharp pain when breathing, or have heart problems or other serious health problems.
If you fall into any of the high risk categories, even a mild bout of flu should be treated by a health professional.
If you are taking medication to fight cancer, or are on medication after organ transplantation or take any medication for HIV/AIDS.
How does a doctor diagnose flu?
Influenza is usually recognisable to health care professionals by the symptoms and signs alone.
Symptoms like a high fever, a dry cough, often nasal congestion and aching limbs, make a diagnosis of flu very apparent. If it is known that flu is active in the community, then the diagnosis of flu becomes even more probable.
The when and how of laboratory tests
It is uncommon for laboratory tests to be done. However, in young children, influenza is easily confused with Respiratory Syncitial Virus (RSV) infection, the para-influenza viruses or adenovirus.
Laboratory diagnosis of a viral respiratory illness might be attempted for one of the following reasons:
- When the illness is severe, requiring admission to hospital;
- To help decide whether an antibiotic is necessary, because viral infections do not respond to antibiotics, but secondary bacterial infections do;
- For surveillance of circulating influenza strains.
How is a laboratory test done?
A throat or nose swab would usually be collected for a laboratory test. Influenza viruses have traditionally been cultured in the chick embryo inside a hen's egg. Nowadays, most laboratories use cell cultures to grow the virus. The specific virus strain or bacteria can be identified with these tests.
How can a doctor treat flu?
- In low risk cases and without signs of severe secondary bacterial infections, the doctor will treat the flu symptoms very much the same way a person will treat himself: mainly with over-the-counter medications. When the diagnosis is clear, there is not much else to be done to "treat" a flu virus other than relieving the symptoms. Studies have shown that in the majority of cases the symptoms of flu will subside within three to four days with or without symptom-relieving medication.
- Over-the-counter cold and flu preparations cannot cure flu, but will relieve symptoms.
- In high risk cases, or people with a secondary bacterial infection, the doctor will prescribe an appropriate antibiotic.
- In more severe cases, the doctor might consider hospitalisation of the patient.
When should you take antibiotics?
The short answer is: when your doctor prescribes it. Antibiotics are only useful in treating secondary bacterial infections when you have the flu. About 5% of colds develop into secondary bacterial infections.
Remember to complete the course of antibiotics. There is a real concern that people do not complete the full course, or take antibiotics incorrectly (and not according to a doctor's instructions). The incorrect usage of antibiotics is one of the main reasons for the increase in antibiotic resistant "superbugs".
Amantadine (tradename = Symmetrel) and rimantadine (tradename = Flumadine) are two similar drugs that have been available for many years. They are effective against influenza A only, and work by preventing the virus from uncoating inside cells, with the effect that it is unable to multiply.
Amantadine and rimantadine can prevent flu in unvaccinated, at-risk people during outbreaks and are of some benefit as treatment if started early. Due to their severe side-effects on the brain and gastro-intestinal system, and the quick emergence of drug-resistant flu viruses during treatment, these drugs are not often used, and very seldom used in South Africa.
Scientists have developed an exciting new generation of antiviral drugs specifically against the Influenza viruses A and B. These new drugs, already in use in the USA and Europe, are zanamivir (Relenza by GlaxoWellcome) and oseltamivir phosphate (Tamiflu by Roche), which are now both available in South Africa.
Reviewed (2006) by Dr Jane Yeats MBChB, BSc(Med)(Hons)Biochem, FCPathSA(Virology).