A virus, depending on the type, can make you ill for a few hours, or can cause death within a few days. Although most of us use the term very loosely, few of us know exactly what a virus is. As you read on, you might be amazed at its structure. Unlike other pathogens (e.g. bacteria), a virus is made of of DNA (Deoxyribonucleic acid), or RNA (Ribonucleic acid).
Many experts consider viruses as living organisms. This bundle of DNA will invade a living animal cell. Once inside it may lay dormant, or it may use the cell's own diving ability to reproduce more of the virus DNA. Because a virus is disguised in the body's own cell shell, the immune system may not detect it, leaving the virus to multiply unchecked. In most cases the immune system eventually recognizes the virus and destroys it. But sometimes it is unsuccessful, such as in the case of AIDS.
Antibiotics, e.g. penicillin, have no effect on a virus. Most times the infected person must wait until the body builds up immunity on its own and destroys the virus. Such as in influenza, or a common cold.
Immunity is the development of anti-bodies. These are specialized cells in the body's immune system, that have been developed to fight a specific type of illness. This happens in response to some kind of infection. Most of the times these anti-bodies will remain around for many years, which explains why it is very rare to get sick from the exact same viral strain. The problem is though that many viruses evolve, meaning they change, and the present anti-bodies are not effective.
However, there is vaccination for many viruses. Developing a vaccine involves taking inactive parts of the viruses DNA. These parts are harmless. But, when injected into the body they immune system reacts by developing anti-bodies. And because these anti-bodies are now present, the immune system is fully ready to fight the real virus, if it ever enters the body. Note, there are many viruses that vaccines have not been developed yet, e.g. AIDS, hepatitis C.
A virus is not as easily infectious as, e.g. bacteria, because it can not live for very long on non-living surfaces. Usually, viruses are transmitted through bodily fluid (blood, vomit, saliva, semen, and vaginal fluid).
Examples of viruses:
- Hepatitis A, B, C
- Rhino viruses (common cold)
- Rubella (German measles)
- West Nile