Pathogenesis

The term pathogenesis means step by step development of a disease

due to a series of changes in the structure and /or function of a cell/tissue/organ being caused by a microbial

, chemical or physical agent

.The pathogenesis of a disease is the mechanism by which an etiological factor causes the disease.

The term can also be used to describe the development of the disease,

such as acute, chronic and recurrent

. The word comes from the Greek pathos, "disease", and genesis, "creation".

Types of pathogenesis include

microbial infection, inflammation, malignancy and tissue breakdown.

Most diseases are caused by multiple pathogenetical processes together.

For example, certain cancers arise from dysfunction of the immune system

(skin tumors and lymphoma after a renal transplant, which requires immunosuppression).

Often, a potential etiology is identified by epidemiological observations

before a pathological link can be drawn between the cause and the disease.