Disease, according to its literal construction, a state of dis-case, or absence of the condition of health, in which all the faculties and organs of the body and mind work together harmoniously and without sensible disturbance. It is common to treat of disease as being functional or organic—i.e. evidenced by changes of function or of structure; but function and structure are so closely allied in fact and in nature, that the more this distinction is examined, the more vague and impalpable it becomes, and it can therefore only be kept up as a provisional and conventional arrangement. (See PATHOLOGY, MEDICINE, GERM THEORY; and for individual diseases, see under their names. The diseases of plants are treated at PLANTS; of animals, under such separate headings as ANTHRAX and DISTEMPER.)
A classification of diseases is a necessary preliminary to any general inquiry regarding them; particularly to such statistical methods as are involved in the tabulation of causes of death by registrars, in returns of hospitals, and of the medical departments of the army and navy, &c. The standard authority in Britain as regards diseases affecting man is the Nomenclature of Diseases, published under the supervision of the Royal College of Physicians of London. We give a short outline of the arrangement adopted in the second edition (1885). The list includes nearly 900 names of diseases, besides the various poisons and injuries specified, which extend it to more than 1200.
I. General Diseases, or diseases of the whole body, and those which may be distributed in several parts at one time.
Group A. Diseases dependent on morbid (i.e. disease) poisons (specific febrile diseases). Sub-group (1) (including all the most familiar)—e.g. smallpox, measles, scarlet fever, typhus, diphtheria, enteric (or typhoid) fever, cholera; (2) malarial diseases—ague, beri-beri, &c.; (3) erysipelas, pyæmia, septicæmia, &c.; (4) venereal diseases—syphilis, gonorrhœa; (5) diseases usually occurring only in animals—hydrophobia, glanders, splenic fever or anthrax.
Group B. Diseases dependent on external agents other than morbid poisons. Sub-group (1) Diseases dependent on parasites, animal or vegetable; (2) effects of poisons; (3) effects of injuries (including heat, cold, electricity, over-exertion, &c.) and climate; (4) diseases produced by errors of diet—surfeit, starvation, scurvy, alcoholism.
Group C. Developmental diseases—immaturity, malformations, debility, old age.
Group D (not classified) includes rheumatism, gout, tumours, tubercle, cretinism, leprosy, anaemia, diabetes, &c.
II. Local Diseases (arranged under the systems and organs of the body affected). Only the most important groups are here given.
Diseases of the nervous system (brain, spinal cord, and nerves). Sub-section (1) Inflammation, abscess, softening, &c. of its various parts; (2) apoplexy, paralysis (many forms), convulsions, epilepsy, hysteria, neuralgia, &c.; (3) insanity, idiocy, &c.
Diseases of the circulatory system (heart, arteries, veins, &c.)—e.g. pericarditis, valvular heart-disease, aneurism, varicose veins. Diseases of the respiratory system (larynx, lungs, &c.)—e.g. laryngitis, bronchitis, pneumonia, pleurisy. Diseases of the digestive system (mouth, throat, stomach, intestines, liver, &c.)—e.g. stomatitis, sore throat (of various kinds), gastritis, enteritis, hernia or rupture, congestion of liver, gallstones, peritonitis. Diseases of the lymphatic system (spleen and lymphatic glands and vessels)—e.g. ague-cake, lymphadenoma, elephantiasis. Diseases of the urinary system (kidneys, bladder, &c.)—e.g. Bright's disease, movable kidney, cystitis, calculus or stone. Diseases of the generative system (testicles, uterus, &c.)—e.g. hydrocele, ovarian tumour. Diseases of the organs of locomotion (bones, joints, muscles, &c.)—e.g. caries, necrosis, synovitis, ankylosis, curvature of spine, club-foot, ganglion. Diseases of the skin—eczema, nettle-rash, shingles, acne, chilblains, corns.