patogeneesis

Pathogenesis refers to the biological mechanisms by which a disease develops. It encompasses the sequence of events from initial exposure to a causal agent or injury to the appearance of clinical signs and symptoms, and it includes the interactions between the causative factor and the host that lead to tissue damage and disease.

Pathogenesis can arise from infectious agents, such as bacteria, viruses, fungi, and parasites, as well as from non-infectious processes. Infectious pathogenesis often involves entry into the host, adherence and invasion, replication, and dissemination, with tissue injury caused by the agent itself or by the host’s immune response. Non-infectious causes include autoimmune reactions, genetic abnormalities, metabolic disturbances, toxins, and physical injury. In all cases, the mechanisms of injury may be direct (damaging cells or tissues) or indirect (triggering inflammatory or immune processes that cause collateral damage).

Key factors shaping pathogenesis include the properties of the agent (virulence, inoculum size), the route of entry, and the local environment, as well as host factors such as age, genetics, nutritional status, comorbidities, prior exposure, and the immune system’s status. The balance between pathogenically active processes and host defense determines the severity and outcome, which can range from recovery to chronic disease, disability, or death.

Pathogenesis is distinct from pathophysiology. While pathogenesis describes how disease begins and progresses, pathophysiology focuses on the functional changes occurring in organs and systems. Together, they help explain why diseases present as they do and how different factors influence their progression.