URTICARIA (NETTLE FEVER) The pathologic picture consists in the appearance of elevated spots or wheals of vivid red color, which often fade off in the centre and itch violently. Their size varies considerably. The wheals may be confluent over a certain area as large as a small plate and even larger, which gives the face an erysipelohl appearance.
The wheals may disappear rapidly, but they may also extend peripherally. We distinguish according to color between urticaria rubra and (if the wheals are white and elevated, of porcelain-like appear ance) urtiearia porcelanea. Should there, besides, be a formation of vesicles, we speak of urticaria bullosa. Should there be extravasation of blood into these vesicles, we have to deal with urticaria Inernorrhagica.
course of urticaria may be acute. There may be a rapid appearance within a few hours and as rapid a disappearance of the entire attack. Very often, however, there may be a recurrence which may take not only a more severe, but even a chronic course. The affec tion which under ordinary eiretunstances may be regarded as a light one, now becomes more severe, so that the children are severely taxed by the intense pruritus and the sleeplessness it occasions, and a retardation of growth is the consequence. In these cases the mucous membranes may be involved; the affection may spread to the larynx and pharynx, causing cedema and dyspncea; even cases of Inematuria and albuminuria have been described and it is not impossible that even urticarial swelling of the intestine and gastric mucosa may develop. Whenever urticaria becomes chronic, it is a tiresome affection. The relapses recur more or less regu larly, and accordingly we speak of a chronic urtiearia. trticaria in infancy is not infrequent and is also observed during the nursing period.
Pathological urticarial pimple exhibits a fir curuseript crdema anti a serous saturation of the papillary body and corium with simultaneous dilatation of the lymphatic fissures and lym phatic spaces of the corium.
to Neisser we have to deal with a vasomotor transudative neurosis, in pursuance of which a more or less diffuse vascular dilatation arises through irritation of the vaso-dilators, in other words an arterial congestive hyperamia which is followed by swelling, arises from the increased secretion of serum or lymph. ITnna believes there is a spasm of the efferent skin veins, and that therefore the development of the wheals is based upon a congestive process. Jarisch looks upon urticaria as the result of two factors acting simul taneously: the general, necessarily central disturbance of innervation of the vessels on the one hand, and the direct lesion on the other.
Etiology.—Urticaria may be caused by external irritation (insect bites, sting of nettles, caterpillars). On the other hand it is unques tionably occasioned by substances which affect the skin from the intes tine. We thus find urticaria after partaking of strawberries and other fruit, of smoked meat, fish, venison, shellfish, cheese, spices, etc. These substances seem even to be able to exercise an influence on the nursing baby through the milk of the mother, at least Firruin observed urticaria in an infant whose nursing mother had partaken of oysters and fishes. In the third place, autointoxication leads to fermentation and putre faction (demonstration of indican and sulphuric ether). Parasites in children's intestines cause urticaria, and this seems to be even the case with echinococci. Whether an arthritic process has any influence on the causation of urticaria (through blood clyscrasia) is still doubtful. It is certainly surprising that Wright asserts having cured urticaria by the internal adtninistration of calcium chloride (through increased coagulability of the blood). General nervous disorders like hysteria are a cause of urticaria, especially in young g,irls. Besides there seems to exist a certain family tendency for the affection.