Herpes (Gr., from herpo, 'I creep'), the name of a group of diseases of the skin, characterised by the presence of clusters of vesicles on an inflamed base. There are two well-defined classes included under the name.
(1) Catarrhal herpes occurs most commonly at the edge of the lip, and often attends some febrile disease, especially acute inflammation of the lungs; but may also follow some local irritation, or be without assignable cause. It is attended sometimes by burning or itching sensations, but rarely by pain. The vesicles dry up into a scab, which falls off in the course of a few days. No treatment is generally necessary; but it is very apt to recur. It appears less commonly on other parts of the face, on the mucous membrane of the mouth, and on the genital organs.
(2) Herpes zoster (Gr.; Lat. zona; Eng. shingles, plural of Old Eng. scngle, 'a girth,' through Fr. from Lat. cingulum, words all meaning 'a girdle') is most commonly met with along the course of one of the intercostal nerves, whence the name. It is now known that the inflammation of the skin depends upon an inflammation of the nerve supplying the area affected, though many forms of inflammation of the nerves occur without producing herpes. Its occurrence can sometimes be traced to a blow, to diseased tissues in the neighbourhood, or to the prolonged administration of arsenic; but more often no cause can be assigned for it. The appearance of the characteristic eruption is generally preceded for some days by neuralgic pain in the affected part; inflammation of the skin in patches, development of vesicles, formation of scabs and their subsequent detachment generally run a pretty uniform course, occupying about a fortnight. In young people nothing is left but slight scarring of the skin; but in those beyond middle life an extremely intractable form of neuralgia often remains, and may persist for months. The disease may occur at any age, but a second attack is quite exceptional. More than one intercostal nerve may be affected at once; but very seldom two on the opposite sides, so that the popular superstition 'that shingles which meet round the body always prove fatal' is not likely to be often practically refuted. Though commonest in connection with the intercostal nerves, herpes zoster may occur on almost any region of the body. The brow is a frequent situation; and if the eye is affected, as sometimes happens, it may be seriously damaged. No treatment seems to be effective in arresting the course of the disease; but painting with flexible collodion, or application of zinc ointment over the inflamed patches, diminishes their irritability.