Write a short note on pathogens.

Explanation

Organisms that cause infectious diseases are known as pathogens.These can harm any living individual or organism by living on them or living in them.
These disrupt the normal physiology of organisms either plants or animals and express certain symptoms. These enter in our body through some source like air, water, food, soil, etc.
The major classes of pathogens are viruses, bacteria, fungi, prions and parasitic.