Natural history of diseases

This document provides an overview of the natural history of disease. It discusses the key concepts including the pre-pathogenesis phase where disease exists in the environment prior to infecting humans, the pathogenesis phase where the disease agent enters the host and the disease progresses, and the epidemiological triad of agent, host, and environment factors that influence disease. It also examines risk factors that increase likelihood of disease, different types of risk groups, how diseases can present along a spectrum of severity, and the iceberg concept of disease where undetected cases exceed reported cases.Read less