The different types of pathogens are bacteria, viruses, fungi and parasites. A pathogen is a microbe or microorganism that causes an infectious disease. There are many different diseases caused by these pathogens.
Although there are pathogenic microbes, not all bacteria viruses, parasites and fungi cause disease. Some are beneficial like the decomposers in nature that recycle dead matter.
Certain bacteria, which are small and uni-cellular organisms, can cause different diseases like tuberculosis, salmonella and typhoid fever. Viruses can also cause viral infections, such as hepatitis and yellow fever. Similarly, parasitic organisms cause scabies and malaria, while fungal diseases are ringworm and candida.
The way in which these infectious disease are transmitted can be through water, food, insect bites and direct and indirect contact. Some examples of diseases transmitted through an insect bite are malaria and bubonic plague. Diseases transmitted through contaminated food or water are salmonella and cholera.