GENERAL HISTOLOGY

Detailed explanation-1: -A pathogen is defined as an organism causing disease to its host, with the severity of the disease symptoms referred to as virulence. Pathogens are taxonomically widely diverse and comprise viruses and bacteria as well as unicellular and multicellular eukaryotes.

Detailed explanation-2: -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.

Detailed explanation-3: -Bacteria. These one-cell organisms are responsible for illnesses such as strep throat, urinary tract infections and tuberculosis. Viruses. Even smaller than bacteria, viruses cause a multitude of diseases ranging from the common cold to AIDS.

Detailed explanation-4: -Infectious diseases are illnesses caused by harmful agents (pathogens) that get into your body. The most common causes are viruses, bacteria, fungi and parasites. Infectious diseases usually spread from person to person, through contaminated food or water and through bug bites.