Etiology.—The consensus of opinion points to both external and constitu tional causes as active factors in most cases of the disease. The possibility and even probability of this disease's being due to a parasite is more or less seriously entertained in some quarters.
In eczema the staphylococcus aureus present in practically pure culture in a large series of examined cases and in vaded the deeper layers of the skin. Ec zema may therefore be considered to be due to a staphylococcic infection. W. Seholtz (Deutsche med. Woch., July 26, 1900).
In some ordinary forms of eczema effloresecnces appear which contain no micro-organisms or sonie the pathogenic nature of which is not demonstrable. In such eases the etiology depends probably upon mechanical or chemical irritation. In other cases ordinary streptococci or staphylococci are seen which can be ob served at any time in any portion of the healthy skin. These bacteria, invading the skin where there is an eczema, may arouse additional inflannnation, the se verity of which depends upon the pa tient's idiosyncrasy and the virulence of the germs. Jadassohn (Wiener med. BIOtter, Aug. 23, 1900).
Bacteriolog,ical studies of 74 cases of this disease showed 23 types of coccus. Absolutely typical eczematous lesions were produced by two of these: the diclimactericus eczeinatis albns Havens and monoclimactericus eczematis vives cens, while a third strongly suspicious form might be called triclimactericus eczematis tennis. P. G. Unna (Wiener klin. Rund., Sept. 16, 1900).
Gilchrist and Sabourand have noted the frequency with which streptoeocci occur in skin lesions. Personal method by which it WaS possible to detect small numbers of tbis organism. Sabouraud's medium is used and inoculated by means of a long capillary tube from which the fluids or crusts to be investigated are aspirated. In more than 100 cases it MIS possible to detect staphylococci in 53.7 per cent.; 27 of these cases were eczema, and in these streptococei were present 17 times. In order to deter mine in what proportion of normal skins streptococci were present, 160 areas in 55 human beings were studied. and streptococei were found in 7.5 per vent. They are most frequent in the axilla and on the hack. These strepto cocci re.semble exactly thos-e found in skin lesions. The artifieial forms of dermatitis are sometimes sterile, and sometimes bacteria in considerable num bers can be obtained from them. In the histological appearance, however, there :Ire some differences between the two forms. In view of the extreme obscu rity of this subject, it is important to study all eases of eczema in two direc tions: first, as to whether there is any internal eondition that may produce them, and, second, the possibility of some external irritant. Frederic
(Altinchener med. \Vochen., .No. 3S, 1901).
Among the constitutional influences which are or seem to be of some impor tance as predisposing or active factors are gout, rheumatism, disorders of digestion or assimilation, dentition, struma, gen eral debility, and loss of nervous tone.
The chief elements of causation in the eczema of elderly people seem to be a debility of tissue and a faulty kidney action. The urine is scanty and of high specific gravity, and often loaded with urates. Sugar is not uncommon. Defi cient bowel-action is likewise common. These facts give a basis for treatment. Local measures will not be successful if these points are not carefully attended to. Bulkley (Trans. Med. Soc., State of Y., '90).
Importance of the vital relations of the cell-protoplasm in the epithelial cells, and of the cellular secretions or excre tions in destroying noxious agencies, on the one hand, and promoting the health of the tissues, on the other, are in danger of being overlooked, in conse quence of the long discussions which take place concerning the bacteriology of eczema, many of which are unsup ported by exact observations or bac teriological research of any sort. Les lie Roberts (Brit. Jour. of Derm., Jan. and Feb., '99).
Many French clinicians regard eczema as being due to internal causes. among which digestive functions play an ex tremely important role. Series of in vestigations into the chemical charac ters of the gastric contents in such eases. with a view to finding additional evidence in support of this proposition. In almost all eases lie finds disordered absorption and deficient motility. The gastric juice also shows hypo-acidity, hydrochloric acid being reduced in amount. many instances there is dilatation. while absorption is consid erably prolonged. Abnormal fermenta tions were a striking. feature in his eases, producing, excess of lactic, butyric, and acetic acids. The prevalence of such gastric disturbances the author consid ers should be borne in mind in all cases of eczema, in order that general treat ment may be employed as well as the local methods indicated for the skin. This also points to the importance of dietary, not only to reduce the tendency to abnormal fermentation, but also to obviate any arthritic complication, for, as is well known, eczematous conditions often accompany gouty symptoms. It is quite possible also that certain indi vidual peculiarities of digestion or ab sorption may have to be counteracted, as there is a certain amount of evidence to show that the ingestion of certain articles of food, such a.s game, spiced and very salt articles of diet, etc., may be the immediate cause of an attaek of eczema. Ileynet (These de Lyon, 1901; Brit. Med. Jour., Jan. 11, 1902).