THE. NEPHRITIS OF OLDER CHILDREN 1. Acute Nephritis (Acute Bright's Disease).
Acute Bright's Disease is defined by Wagner as follows:—"A renal disease in which the urine will be scanty for clays and weeks, in which albumin is found, and in which the different forms of casts are present in varying quantities, and in which there occur white or reel blood corpuscles, and epithelium. Besides this there is sometimes pain in the region of the kidneys, and often frequent micturition. There is a varying degree of general disturbance and in serious cases, after a few days or weeks, there is added dropsy of different organs, urannia, and inflammation. After a course varying from a few days to several weeks, either a complete cure is effected or the disease becomes sub acute or chronic, or else death results. It is rather unusual to be unable to assign a cause; in most cases the cause of the illness is some serious infectious disorder. In a certain number of cases the acute Bright's disease is the only thing that can be demonstrated, but much more fre quently there exists some other disease, either still at its height (many of the acute infectious diseases, such as diphtheria, typhoid, pneumonia., acute or chronic external or internal diseases), or else convalescing or completely terminated (scarlet fever). The symptoms of acute Bright's disease are therefore frequently mixed. Some, which proceed from the renal disease, are indicated by the urine; others are due to the original diseases. It is sometimes very difficult to decide whether the latter (e.g., fever, cerebral, and gastric symptoms) are due to the renal or to the primary affection." Postinfective nephritis probably does not, in the majority of cases, result from the direct action of the bacteria, but from toxic influences. Many bacteria pass in the blood stream through the kidneys (staphy lococci, streptococei, typhoid, coli communis, and tubercle bacilli), but this does not necessarily lead to inflammation or abscess formation.
The prototype of the acute infective nephritis which is due to toxic influences is the scarlatinal nephritis, of whieh Wagner has distinguished two forms: the initial and the ordinary variety. It seems preferable, however, to re.serve the term scarlatinal nephritis for that renal disease
which exhibits special clinical features and histological symptoms, and which appears only after the entire remaining process seems to have terminated. Albuminuria, with casts occurring at the aeme of the erup tive disease would be better de.signated as "albuminuria scarlatinosa." This affection evidently belongs to that great group of albuminurias which have so intimate a relation with the fever that notice of the con nection has been shown by the denomination "febrile albuminuria." With good reason Liithje has emphasized the fact that in this form of albumin secretion also there are probably inflammatory and degenera tive ehanges in the renal structure, but it seems proper, nevertheless, to restrict this -variety of albuminuria with casts, because it commonly disappears entirely with the subsidence of the fever, and beeause its anatomical basis is not yet perfectly understood. Another renal affection, the "septie nephritis," which accompanies scarlet fever. must lie sepa rated from the searlatinal nephritis because in a strict sense it has noth ing to do with the scarlatinal process proper. It is not distinguished in any way from the nephritis which aecompanies other septic conditions, and with which its symptomatology is identical.
(a) Nephritis Accompanying Scarlet Fever (Nephritis Scarlatinosa) This affection is a relatively frequent complication of scarlet fever. IIeubner in a series of 35S cases observed 36 eases of nephritis searla tinosa, i.e., almost 10 per cent.; in another series of 393 eases he ob served the characteristic renal disease 77 times, i.e., in 19.6 per cent,.
The underlying cause of the nephritis searlatinosa seems to be dif ferent from that whieh produces the exanthem and the acute reaction. Neither poison has as yet been isolated, and we know only one factor in the whole process whieh predisposes to the appearance of this dreaded complication, and this is the "epidemic tendency," a factor which was recognized by Wagner. We now know that there are epidemics in whieh nephritis appears in scarcely 5 per cent. of the cases, and others in which it occurs in more than 70 per cent. tSteiner, Johannesen).