RESPIRATORY VIRAL SCREEN

Viruses are minute infectious agents that multiply inside living cells. They are so small that most can only be seen with an electron microscope. Their sole activity is to invade cells of living organisms which they take over to make copies of themselves. All viruses have the same basic structure but their shape or size may vary. Unlike bacteria viruses cannot be grown in culture and antibiotics are not an effective treatment against them. There are some anti-viral drugs now available that work by either preventing viruses from entering a cell or by altering their ability to replicate.

Viruses can cause disease in a variety of ways:

They may destroy or disrupt the activity of the cells they invade - seriously so if vital organs are affected
The response of the body's immune (defence) system may lead to symptoms - fever and fatigue
Interaction with the chromosomes of the host cell - i.e. viruses can cause cancer
They may cause disease by weakening the body's immune (defence) system allowing other illnesses to develop - as in AIDS.

The body's defence to virus invasion is fairly rapid but a virus is able to hide from the immune system allowing the infection to recur or become chronic.