CONTAGIOUS DISEASES OF CHILDREN. 253 



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 dis- 

 charge 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 condi- 

 tion 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 para- 

 site 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, un- 

 equal, puckered, crust-like yellowish scabs, which may be single or may 

 cover the entire scalp. The scabby flakes in drying and dying crum- 

 ble to minute fragments, and as dust propagate and disseminate the 

 disease. Itching being frequent in scalp ring- worm, the child's scratch- 

 ing 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 school- 

 fellows, and only be readmitted on presenting a proper medical cer- 

 tificate. 



Common ringworm, or Tinea tonsurans, is very contagious, mak- 

 ing 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 artifi- 

 cially clipped off at a distance of say y 1 ^ to - 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 maybe 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 con- 

 tagious complaint declares itself by the presence of defined patches 

 naked of all traces of hair having a glistening ivory whiteness not un- 

 like 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- 



