Ophthalmia.—Both catarrhal and purulent ophthalmia are highly contagious at all ages, but especially in very young children, and the last-named disease may cause the loss of one or both eyes.
The eyes and their lids become red, swollen, and bathed with a discharge often more or less offensive.
Contagious Parasitic Diseases.—Itch is characterized by the appearance of minute transparent vesicles, which occasion the most lively itching, particularly at night-time. The spaces between the toes and fingers, and the wrists, are most liable to invasion. The child's frequent scratching soon converts the rash into scabs, in which condition the disease will frequently first be noticed by the teacher.
The itch is caused by an insect (Acarus scabei or Sarcoptes) which is nocturnal in its habits and movements. Though highly contagious, the itch can be cured in a few hours.
Crusted ringworm, or Tinea favosa, is caused by a vegetable parasite frequenting the scalp, although it may visit other parts of the body which are covered with hair or down. The hair becomes thin and fragile, with loss of its original color; then follow irregular, unequal, puckered, crust-like yellowish scabs, which may be single or may cover the entire scalp. The scabby flakes in drying and dying crumble to minute fragments, and as dust propagate and disseminate the disease. Itching being frequent in scalp ring-worm, the child's scratching increases the destruction and pulverization of the scab, and thus increases the chances of contagion to others.
The heads of such children as suffer from the disease have a peculiar fetid odor resembling that of a cat's urine. Till quite cured, every child suffering from favus should be separated from its schoolfellows, and only be readmitted on presenting a proper medical certificate.
Common ringworm, or Tinea tonsurans, is very contagious, making itself manifest by the hair of the head becoming thinner, more fragile, less colored than the surrounding hairs. The affected hairs are apt to turn reddish or ashy-gray; they seem as if evenly and artificially clipped off at a distance of say 114 to 18 of an inch above the level of the outer layer of the skin. The surface of the patches is rough, irregular, shaggy, covered with a grayish, scurfy powder of a slightly bluish tinge. The diseased places may be one or more in number; the form is circular, varying in size from that of a silver florin to a crown piece. By the fusing together of several of such parasitically affected localities the greater portion of the scalp may become affected.
Ringworm with Baldness of Scalp (Tinea decalvans).—This contagious complaint declares itself by the presence of defined patches naked of all traces of hair having a glistening ivory whiteness not unlike a scar without depression. Their size varies from that of a silver threepenny-piece upward.
Previous to the loss of hair there may have been considerable itch-
