Varieties. — (A) DERMATITIS FROM VEGETABLE IRRITANTS.—A large num ber of plants, some of them used medic inally, possess irritant properties when brought in contact with the skin.
Rhus, or Poison-ivy. — Among the above the most important are various species of Thus; namely Rhus toxicoden dron, or poison-ivy; Rhus venenata, or poison-sumach; and Rhus diversiloba, or poison-oak. The latter, according to J. C. White, is a native of the Pacific coast, although the common R. tox icodendron is also vulgarly known as poison-oak.
-When a person, susceptible to the poison of one of these species of rhus, touches the plant, or, in some cases, even comes within a short distance of the same, the skin shows signs of irritation manifested as follows: There may be redness, but more frequently the first objective sign is the eruption of groups of small vesicles, accompanied by swell ing and intense itching. In consequence of the scratching set up, the vesicles are ruptured and exude an abundant serum. The swelling is sometimes very great, especially about the loose tissues of the face and the genital regions. The eruptions usually begin upon the hands, as these are the parts of the body most frequently brought in contact with the poison. From the hands it is generally transferred to the face, and next, in the male sex especially, to the genitals, be cause the face and genitals are the parts most frequently handled. The face and head are often so intensely swelled as to be almost unrecognizable.
[I have a vivid recollection of a per sonal attack of this eruption. When a boy 1 had frequently exposed myself to the poison without becoming affected. After a residence of some years in the city, I deliberately exposed myself, on a visit to the country-, and within twenty-four hours my hands and face were swelled, covered with vesicles, and intensely itching. In the course of the next twelve hours the genital organs became swelled and studded with vesi cles. Sleep was impossible from the most intense irritation. The scratching produced erosions, exudations of serum, and the formation of crusts, which finally fell off, leaving a slightly-red dened and somewhat exuding surface beneath. The itching was only partially controlled by the frequent application of concentrated solution of common salt. The eruption lasted about a week. GEORGE H. RonE.] Sometimes the skin is very much reddened arid the exudation abundant.
Excoriated patches are frequent. The itching varies from mild grades to the most severe intensity, but is generally a prominent symptom. It is said that death has followed the poison, but the testimony upon this point is rather vague.
The common belief that an eruption caused by rims poisoning is liable to recur annually without renewed exposure is not based upon sufficiently-definite evidence. The fact that the dermatitis recurs at about the same time each year is to be attributed to a new exposure. White, however, mentions a number of cases in which a different eruption fol lowed—after an interval—the attack of rims poisoning.
The chemical nature of the poison of the various species of rhus is somewhat obscure, but a number of researches in dicate that it is a volatile acid. A num ber of cases are on record showing that handling dried specimens of the poison ous plants may- produce an eruption. The time after exposure when the erup tion appears differs in different persons. The shortest is, perhaps, four or five hours, while in some cases it may be as many days before the effects of the poi son on the skin are manifested. That the poison before volatilization may be transferred from one portion of the body to another—as from the hands to the face or to the genitals—is beyond ques tion.
Case of dermatitis venenata conveyed to a patient in the obstetrical ward of a hospital by the attendants, who had, just before the patient's delivery, gath ered a quantity of poison-ivy, and then, although having previously carefully washed their hands, had manipulated the patient's abdomen. J. Abbott Cantrell (Med. News, Oct. 24, '91).
It has been hitherto accepted that the toxicodendric acid described by Alaisch was the active principle of rhus poison ing, but found to be merely acetic acid. A poisonous oil, however, termed "toxi codendrol," is the toxic element,—a very intense skin irritant, even in minute quantity. Like cantharides, it can pro duce nephritis and fatty degeneration of the kidneys, and it is probable that fatal results of rhus poisoning may have been due to renal complications. It is non-volatile; actual contact appears necessary. The activity of toxicodendrol in minutest traces may make it possible for a few pollen grains of poison-ivy to cause skin eruption; and the few cases of action at a distance. which are so often quoted, mhy conceivably be thus explained.