Types of Disease
DISEASES are classified in various ways. In or¬ganic diseases the structure of an affected organ of the body is altered. In functional disease there is no visible change in structure, but failure of organs or parts of the body to perform their functions. When a communicable disease occurs in a certain locality more or less constantly it is said to be endemic. When it affects a very large part of a community it is said to be epidemic; when an epidemic spreads over a large stretch of a continent or of the world it is called a pandemic. Detached cases of a com¬municable disease in a given locality are spoken of as sporadic. An acute disease is sudden and rapid in its development; when slow or gradual, the disease is said to be chronic.
Curative methods of treating disease may be hygienic, dietetic or manipulative, or combinations of these. Preventive methods usually are hygienic and dietetic, but sometimes other methods also are applied.
Pathology is the study of disease. Etiology considers the causes of disease, which may be internal or external, specific, primary, or secondary, predisposing and exciting. Symptom¬atology is the study of the various symptoms and signs whereby the disease is detected and diagnosed; these may be objective or subjective. Objective symptoms are those evident to the observer or examiner, while subjective symptoms are those that are apparent only to the patient himself. Diagnosis is deter¬mination of the nature of disease, while prognosis is the fore¬cast of the outcome of a disease.