Bacteria and Viruses - what's the difference?

Both are microscopic. Both cause diseases.

Bacteria are single-cell organisms that live everywhere.  Some are beneficial - for example help us to digest food.  Others, called pathogenic, cause illnesses.  Bacteria are self-sufficient and can replicate themselves from any other living cell through subdivision.

Viruses are typically 1 to 100 times smaller than bacteria.  Viruses can only reproduce by entering a living cell.  Drugs which target viruses are usually very toxic to the host cell.

Antibiotics kill bacteria, but not viruses.  In fact, if you take antibiotics to try to treat a viral infection, this will affect the virus and may cause other unwanted effects.

Other microscopic invaders that cause disease include fungi - slightly larger than bacteria and responsible for conditions such as candida and protozoa - tiny single cell parasites such as Cryptosporidium that can live in your body.

(Excepted from Reader's Digest Sep 2009 Edition)