This group is numerous and only the relatively important ones will be considered. It is unwise because of the comparative rarity of many of the resultant irritations to dignify each with a separate name. So under the title of the offending parasite will be considered the eruption caused by it. Broadly speaking, most of the parasites belong to the groups, dermatozoa, parasites living for a time in the skin of which the acari are the commonest living for a time in the skin of which the skin, usually to obtain nourishment, of which the pediculi are the best known examples.
The brown-tailed moth, the scourge of New England and parts of Canada, has been known on this continent for about ten years. Besides destroying fruit trees and other vegetation, the short barbed hairs of the moth, cocoon, and caterpillar are responsible for a multiform eruption (brown-tail moth dermatitis) in the human species. There is usually itching followed by discrete erythematous macules and wheal-like swellings. The dermatitis may become eczematous and last from a few days to several weeks. It may be limited but the face, neck, arms and the upper part of the trunk are the favorite sites.
Treatment if similar to that prescribed for other forms of dermatitis, pruritus and eczema. Carbolized solutions and ointments are extensively used. Mercuric chlorid lotion (1:1000 to 1:2000) followed by the application of flexible collodition has been recommended. In the treatment of a number of cases in 1904,
I found orthoform, I dram to an ounce of vaseline or simple cerate the most effective external application.
This is a small mite sometimes found infesting straw and grain and may cause an eruption known as straw or grain itch. These mites do not burrow into the skin except for the purpose of nourishment, possibly injecting a toxic substance at the same time. The eruption is seen upon the trunk, especially on the upper two-thirds, on the upper parts of the arms and on the neck. It is discrete, moderately abundant, with a troublesome itching. It consists of small erythematous abundant, with a troublesome itching. It consists of small erythematous papules or papulovesicular lesions, occasionally urticarial or varicelliform in character. This condition is commonly seen during the warm months and while all ages are liable, it usually occurs in those who handle infected grain or straw, or sleep on mattresses containing such material. Diagnosis may be established by the abrupt onset, intense itching, epidemic occurrence, distribution and uniformity of its lesions, and a suggestive history.
Treatment consists in the use of weak betanaphthol or sulphur ointments, or carbolic acid in ointment or lotion, plus the prompt removal of the cause. The condition will usually subside in from one to two weeks.
The common bedbug only visits the skin to feed. It injects therein an irritating fluid producing an immediate flow of blood which it proceeds to suck. The eruption is an inflammatory papule or wheal with a central hemorrhagic puncture. Scratching may cause further lesions. The only effective treatment is the destruction of the parasite or retreat on the part of the sufferer. Alkaline and carbolic acid lotions, alcohol spirits of camphor or tincture of ledum will relieve the irritation.
The common flea is found everywhere but especially in tropical climates. Its bite causes a small erythematous spot with a central hemorrhagic point, which may pass through the gradations of color as observed in purpura simplex.
Treatment. The wearing of bags filled with gum-camphor beneath the clothing or the use of bags containing pyrethrum powder pinned to the underwear, have been recommended as efficient prophylactic measures. Lotions of carbolic acid or thymol will relieve the irritation.
Wood ticks of several species occasionally attack man to secure blood. A urticarial lesion marks the site of the attack and may be itchy or painful. If found on the skin the parasite should not be forcibly removed but should be induced to quit by the application of turpentine, benzoin or tobacco juice. It can then be removed safely and a dilute solution of thymol applied.
DERMANYSSUS AVIUM ET GALLINAE
Mosquitoes (culex sollicitans, culex pipiens, etc.), gnats, midges, certain kinds of flies, bees, wasps, spiders, ants, caterpillars, etc., may attack the skin from various motives. Some of these lesions are of little importance and subside rapidly. A certain amount of idiosyncrasy in the individual may account for persistent or secondary eruptions. The lesions are usually erythematous or urticarial with a central punctum. The history that many of these minor parasites have revealed in the shape of their activity in the transmission of disease, rather than in any inherent quality that they possess to cause a morbid conditions, makes their consideration most interesting. Treatment consists in the application of spiritis of camphor, baking soda solution, weak ammonia water, or two per cent. menthol solution. Often protection from the parasite is important and for this purpose the essential oils may be used.
The harvest bug, or mower’s mite, is a minute reddish insect, barely visible to the naked eye, which may be found in the summer and autumn on the grass and bushes and when accidentally lodged upon the skin of persons working in the field or garden, may burrow its head in a follicle. The irritation caused thereby may be erythematous, urticarial, papular, vesicular or pustular and is usually located on the skin of the ankles, legs, feet and arms. The insect does not long survive on the skin, and the resulting eruption will quickly subside spontaneously, or on the application of alcohol, spirits of camphor, or weak ointments of sulphur or balsam of Peru.
The jigger, chigger, or sand-flea, usually found in tropical or warm countries, resembles the common flea except that it has a long proboscis. Only the impregnated female does the damage. She burrows into the skin producing vesicles, pustules, nodules and even abscesses, ulceration and adenitis. Treatment consists in the early removal of the flea with a blunt needle or probe and the local application of carbolized, borated, or alkaline lotions. Essential oils may be recommended as a preventative.
(Filaria medinensis; Guinea-worm)
This is a parasitic, cylindric nematode worm only encountered in tropical countries. The matured female averages about 25 inches in length, one-tenth inch in thickness, has a convex head, curved and pointed tail and presents a milky color. The migrations of this worm, which give no trace until fully developed, may be extensive. The point where it seeks exit from the skin will present a cord-like appearance. The first visible lesions are pea-sized or larger vesicles, pustules or nodules, attended with pain and swelling. The foot is the common seat of exit. The study of this worm makes it almost certain that the larvae enter the human body through the drinking water after they have developed from embryos in the body of a minute aquatic animal organism and, being swallowed by man in water, they escape into the gastro-intestinal tract and undergo further development and impregnation. Some, including all the males are expelled in the feces, while the surviving females migrate as mentioned above. No possible diagnosis can be made until the worm can be seen or felt, although its endemic character should be remembered.
The treatment advised by Emily appears to give the best results. It consists in the injection of mercuric chlorid (1:1000) into the swelling produced by the worm before she has ruptured the skin. The worm having been killed may be absorbed or removed by incision or, if the head has already appeared, the solution is injected into the body of the worm.
The hydatids of taenia solium are sometimes found in pea-to walnut-sized tumors in the subcutaneous tissue and covered by unchanged skin. It is most often seen in countries where half cooked or raw pork is commonly eaten containing the ova of taenia. If the tumors are punctured a clear fluid will run out in which may be found the pathognomonic hooklets. The cutaneous lesions are of importance only in relation to hydatids of some internal organs. A microscopic test will often be needed to diagnose these growths from gumma, lipoma, epithelioma and sarcoma.
This worm-like, minute microscopic parasite was discovered by Henle in 1841. It is found in comedo-plug, sebaceous glands and hair-follicles in cases of acne and seborrhoea oleosa, as well as in normal cases. Pigmentation of the skin has been reported as traceable to this parasite. It may be successfully treated by repeated soft soap washings.
The larvae or ova of the gadfly and botfly may be deposited in exposed parts of the skin in a puncture made by the adult insect and may give rise to furuncle- like tumors followed by suppuration, during which the worm can be pressed out or extracted. This manifestation is fairly common in Central and South America. A condition met with occasionally in this country but more commonly in southern Russia known as larva migrans or creeping eruption, may be considered as due to the larvae of the botfly.
Treatment of this formation is by free incision and pressure followed by applications of an antiseptic to the wound. In migrating or serpiginous forms, the larvae may be secured by excising or cauterizing the area around or beyond the spreading lesion. The cataphoretic application of mercuric chlorid, 2 grains to the ounce, has been recommended.
This is a condition observed chiefly upon the west coast of Africa in which both nematodes and filaria have been found. It resembles scabies in attacking the fingers and forearms and presents itching vesicles, papules and pustules. Excoriations and crusting results from scratching, but the typical burrows, distribution and history of scabies are absent. Treatment involves cleanliness and the use of parasiticides but the diseases is often persistent and rebellious.
The larvae of this tinea have been found in the human skin as encapsulated soft tumors and vesicles which produce a sensation of tension and undergo a fatty or calcareous degeneration after the death of the parasite. Extirpation is the only treatment.
The embryos of the large liver-fluke have given rise to encapsulated tumor-like formations in the subcutaneous tissues of human beings in three reported instances. The distoma must be found to establish a positive diagnosis.
This intestinal parasite and similar varieties belonging to the nematode family, Strongylidae, are principally interesting as the cause of the so-called hookworm disease. It was formerly thought that its larvae found entrance through the mouth in food or water, but it is now known that a common form of entrance is by means of the skin of the feet and legs. Here erythematous, papular, vesicular or bullous eruptions may be found. It is intensely itchy and is often first noticed between the toes. Clean linen, mild antiseptic or antiparasitic ointments or lotions are indicated for the skin lesions. Prophylaxis is a most important item of treatment.
This and similar minute flagellate parasites which invade the body by means of an insect (the common fly, Glossina palpalis, or the tsetse fly) acting as host, cause a disease known as trypanosomiasis or in its advanced stages “sleeping sickness.” The puncture made by the insect referred to, may cause a deep red furunculoid swelling, followed by pigmentation. As the constitutional symptoms become more pronounced, so the cutaneous aspect changes and new lesions appear. Prophylaxis, protection against the insects, is the most important point in treatment. Locally antiseptic and antiparasitic lotions may be used. Arsenic is the mainstay of internal medication.