Page:A Handbook of the Theory and Practice of Medicine - Volume I - Frederick T. Roberts.djvu/256

240 THEORY AND PRACTICE OF MEDICINE.

This term is applied to very different diseases, some of which are entirely of a local nature. For convenience sake, however, it will be expedient to consider all the varieties in the present chapter.

Etiology. — The immediate pathological cause of rheumatic fever is the presence in the blood of a morbid material, g-enerated within the system in consequence of some derang-ement of the nutritive and eliminatory processes. This is generally presumed to be a normal ingredient of one of the ordinary excretions, only accumu- lated in excess, the common belief being that it consists of lactic acid. The results of experiments seem to favour this view, the usual phenomena of acute rheumatism having been produced by injecting this acid into serous cavities, as well as during its in- ternal administration. Some authorities believe that rheumatic fever is primarily due to some disturbance of the nervous system.

Exciting causes. — The ordinary exciting cause of acute rheuma- tism is a sudden chill, induced by exposure to cold and wet; sitting in a draught when heated or perspiring ; neglecting to change wet clothes ; or in various other ways. In not a few instances no de- finite cause can be fixed upon, and it is quite conceivable that dis- ordered processes may be gradually carried on in the system, which tend to generate an amount of the poison sufficient to set up the complaint under very slight provocation. Errors in diet, sup- pression of menses, and various other disturbances have been ranked as causes of acute rheumatism. Scarlatina seems to lead to this complaint sometimes, probably by interfering with the ex- cretory functions of the skin.

Predisposing causes. — Acute rheumatism is distinctly a hereditary disease, and it tends to run in families. It chiefly attacks persons from 15 to 35 years old, being especially frequent between 16 and 20, but no age is exempt, and I have met with a good many cases in young children. Previous attacks decidedly increase the pre- disposition to the disease. More cases are met with among males, and in the lower classes, on account of their greater exposure to the ordinary exciting causes. Climate and season have considera- ble influence, the affection occurring mainly in temperate but very moist climates, and where sudden changes in temperature are ex- perienced. It is far less common in tropical and very cold coun- tries, _ A large number of cases are met with in the eastern counties of England. The same conditions influence the prevalence