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Viral infection  

What is a viral infection?

Viral infections are caused by viruses, which are microscopic germs and are quite different to the larger bacteria germs. They look like tiny crystals under the microscope. They are the commonest cause of infection, but are usually not serious. We eventually get over the infection simply by resting and looking after any troublesome symptoms.

What are examples of viral infections?

They usually cause upper respiratory tract infections (URTIs) such as the common cold and pharyngitis (sore throat). Other examples are influenza, gastroenteritis (especially in children), measles, rubella, mumps, chickenpox, glandular fever and cold sores.

What are the typical features?

• The illnesses are bothersome, but usually not serious.
• Symptoms include feeling unwell, fever, aches and pains (including headache).
• The illness is 'self-limiting'; that is, it gets better naturally.
• The body builds a defence by producing antiviral antibodies.
• Normal routine antibiotics have no effect on the outcome.
• Serious complications are rare, but dehydration can be a special problem in children and we have to watch out for encephalitis (inflammation of the brain) with some, such as mumps and measles.

What is the treatment?

• Rest to allow the body to shake off the virus.
• Take analgesics (paracetamol or aspirin) for fever and aches or pains. Use paracetamol in children.
• Take adequate fluids, especially children. Use clear fluids such as water.
• Use decongestants for URTIs.

Why not give antibiotics?

Routine antibiotics do not help viral infections. Bacterial infections are generally more serious and are cleared up by antibiotics.

However, bacteria can attack the affected vulnerable parts of the body during a viral infection and cause problems such as middle ear infection, sinusitis, bronchitis, pneumonia and skin infection. You or your doctor may notice a yellowish-green nasal discharge or sputum, pus in the middle ear or throat. Antibiotics may be prescribed to treat this secondary bacterial infection.

When should you contact your doctor?

Contact your doctor if any of the following occur:

• no improvement in condition or worsening after 48 hours
• refusal of a child to drink
• persistent vomiting
• difficulty in breathing
• persistent headache
• complaints that any light hurts the eyes
• paleness and drowsiness
• pain not relieved by analgesics
• pus-like discharge from the ear, nose or skin, or in the sputum

Copyright 1995: John Murtagh, Professor of General Practice
Monash University, Melbourne, Australia