19 Understanding and Reporting the Natural History of an Infectious Disease

Accurate characterization of the natural history of a disease is often inadequate in outbreaks of novel or re-emerging infectious diseases. Through the lens of the host–pathogen–care interface, the stages, outcomes, and determinants of the natural history are considered, with emphasis on how the natural history might suggest interventions to improve acute and convalescent outcomes. Understanding the natural history directly informs not only clinical care but also preclinical development and discovery of medical countermeasures and sets the stage for design of high-quality clinical trials of the same. Conducting optimal natural history studies is challenging during an infectious disease emergency; strategies to enhance understanding and report natural history as part of the emergency research response are discussed.