What is a pathogen? and how does it cause disease?

Pathogens are microorganisms that cause disease. They may be bacteria, viruses, protists or funghi. They can infect animals and plants, causing a wide range of diseases. 

Pathogens, such as bacteria and viruses cause disease in a number of ways. Bacteria divide rapidly by splitting in two (via binary fission). They may produce toxins that affect your body and make you feel ill. Sometimes they directly damage cells. Viruses take over the cels of you body. They live and reproduce inside the cells, damaging and destroying them.