The Pathophysiology of Infectious Disease 'How do microbial pathogens cause disease?'

摘要

Infectious agents establish infection and damage tissue in 3 ways: They can contact and / or enter host cells and directly cause their death. They can release toxins (either exotoxins that are secreted by the living cell or endotoxins that are released by the dead or effete cell) that kill cells at a distance, release enzymes that degrade the local or distant tissue components or damage blood vessels and thereby cause ischaemic necrosis. They induce host cellular responses that cause additional tissue damage even though the response is primarily directed at the invading microbe. This makes the host response both a benefit and a detriment. The extent to which an organism (whether, viral, bacterial, fungal, protozoal or parasitic) exerts its pathogenic effects depends on several factors including:The extent of innate or natural host resistance to the organism. The specific properties of the organism itself (and its ability to cause disease in the target species). The virulence of the organism is a major factor in its ability to cause pathologic disease.