RACHITIS Occurrence.—Rachitis is an extraordinarily wide-spread disease. It occurs most frequently in the civilized portions of the north temperate zone, where in the poorer quarters of great cities it affects 90 or more per cent. of all children. It is comparatively infrequent in the tropics on the one hand and in the far north on the other and also at high altitudes. It is very rare among the children of the yellow races, but although negro children in the tropics remain practically exempt those in regions in which it is endemic seldom escape.
Symptoms.—The most characteristic symptoms of rachitis are those of the osseous system; in addition to these certain general manifesta tions which are apt to be most evident occur in the majority of cases at the beginning of the disease at a time when the bony changes are not yet clinically evident.
(a) Constitutional Symptoms.—These are quite ambiguous. The children become restless, ill-tempered and do not sleep as well as usual. If they lie on their back, especially in sleep, they roll their heads from side to side or burrow them into the pillow, though if they lie on the side they usually remain quiet. Children over six months of age with this disease learn to seek the latter position of their own accord, not infre quently gradually lying even partially or wholly on their faces. When such a child is carried it is unable to hold its head erect for more than a short period of time, and usually supports its cheek or face against the face or shoulder of the nurse. Oftentimes the friction of the head on the pillow leads to baldness of the occiput.
Another important symptom is sweating. This affects the head, principally, where it is often so marked that in the morning the child's pillow is soaked through. The sweat is of a clammy nature, with an acid odor and reaction. Oftentimes sudamina or eczema follow' in the wake of the excessive sweating. Coincidentally the vasomotor excita bility of the skin undergoes an abnormal increase, so that red spots appear in a short time over any area where friction is exerted. Very frequently the urine assumes an offensive penetrating odor. In chil
dren old enough to run about the absence of desire to do so is often a very early symptom of the disease.
If these initial symptoms are very marked the children lose their fresh appearance and become more or less pale and flabby. In many cases the constitutional symptoms are so slight that the disease begins apparently with those referable to the bones, though the former are usually manifest at least two or three weeks before the undoubted bony changes are evident.
(b) Osseous System.—The bone changes due to rachitis may be comprised in the terms "softening" and "deformity." The softening affects principally the flat bones and the diaphyses of the long bones, but the de formity may affect any bony part. They are constant even in cases in which gross defor mity never appears. As the result of the disturbance of the bony growth the epiphyses of the long bones enlarge, es pecially at the points of union between the bony and carti laginous ribs where they can become so marked that they appear as large nodules lying under the skin. The skin not infrequently forms a deep fold in the plane of the articulation, especially at the wrists.
In the majority of the more chronic cases a deform ity of the cliaphyses is gradu ally superimposed upon the enlargement of the epiphyses. Such deformities frequently take the form of marked exag geration of the normal bony curves, but the essential con dition underlying these im portant changes of form is always some trauma which bends, or much more rarely fractures, the abnormally soft hones. Marked displacement of the fragments is usually absent, even with complete fractures, since the continuity of the thick ened periosteum almost always remains intact. The consolidation of the callus is much delayed by rachitis. The force which is necessary to bend or break a rachitic bone is in inverse ratio to the extent of the bony softening. In the worst. cases therefore very careful protection of the child is necessary. Often in a very short time the bones become markedly softened, even under the eyes of the observer.