Bacteria pathogens are microscopic organisms which come in all shapes and sizes the largest being only 10 micrometers long (10 millionths of a meter). They are also living cells, and when in favourable conditions they can multiply rapidly. They make you feel ill by releasing poisons or toxins into your body!!!

Viruses are many times smaller than bacteria, in fact they are one of the smallest organisms known!!!. they are made out of genetic material which is protected by a protien coat!!! Viruses can only reproduce inside host cells, and damage the cell as they do this. Onced they have got inside the cell the viruses creates hundreds of thousands of copies of itself. when the cell is full with the copies of the virus it bursts open letting the virus flow down into the blood stream, or into the airways!!!