PATHOLOGY

Detailed explanation-1: -The diseases that can spread from an affected person to a healthy person and are caused by pathogenic microorganisms are called infectious diseases. Bacteria, viruses, protozoans and fungi are common pathogens that cause infectious diseases.

Detailed explanation-2: -Pathogens. A pathogen or infectious agent is a biological agent that causes disease or illness to its host. This term is most often used for agents that disrupt the normal physiology of animal or plant. Pathogens can be a bacterium, virus, or other microorganisms that can cause disease.

Detailed explanation-3: -Infectious diseases are caused by pathogens, which include bacteria, fungi, protozoa, worms, viruses, and even infectious proteins called prions. Pathogens of all classes must have mechanisms for entering their host and for evading immediate destruction by the host immune system. Most bacteria are not pathogenic.