Infectious diseases are a major cause of morbidity and mortality worldwide. There are many different types of infectious diseases, caused by different agents, including bacteria, viruses, parasites, and fungi. Infectious diseases can be spread through the air, by contact with infected people or animals, or through contaminated food or water.
An infectious disease is an illness resulting from the presence of an infective agent in the body that causes a harmful effect on the host's tissues and organs. The infecting agent can be one type of bacterium or virus, one type of parasites such as a worm, or one type of fungus such as Candida albicans that causes thrush in humans.
The study of infectious diseases is a discipline of medical science that deals with the study of infectious diseases, their causes, their transmission, and their prevention. The field includes epidemiology, microbiology, and immunology.
