CHAPTER XXXIV

MINOR TROPICAL AFFECTIONS OF THE SKIN

DERMATOPHILIASIS

This is a skin infection due to the penetration of the region about the feet and especially the toes by the female sand flea or chigoe. It is also sometimes called the jigger. This flea is a member of the subfamily Sarcopsyllinae which differs from the ordinary flea subfamily in that the impregnated female becomes fixed in the tissues of the host instead of developing her eggs in a free state. The proper name for this flea is _Dermatophilus penetrans_, synonym _Sarcopsylla penetrans_. It is found abundantly in Central America and Northern South America as well as in the West Indies. It is also found in East and West Africa as well as India and is apparently rapidly spreading over the tropical world.

[Illustration: FIG. 130.—Sandflea female; much enlarged. (From Mense.)

FIG. 131.—Sandflea male; much enlarged. (From Mense.)]

This flea attacks not only man but many wild and domesticated animals as well, and in particular the pig. The males and females live in dry sandy soil and feed on the blood of various mammals. The importance of the parasite is that upon impregnation the female ceases to lead a free existence but burrows into the tissues of man or other host and becomes enormously distended with eggs. There is some question as to whether these eggs are extruded by the female or whether they are set free in the ulceration process which tends to occur around the imbedded flea. The eggs develop into 13-segment larvae, which form a cocoon from which the insect comes out in about ten days.

[Illustration: FIG. 132.—Sandflea female. Shortly after penetrating the skin. The anterior part of the abdomen is much more distended than the posterior; the enlarged part is disk-shaped, not globular. (From Mense.)]

The female flea tends to burrow into the skin about the sides of the toe nails, although more rarely boring into other parts of the body as penis, scrotum, thighs or hands. Finally only the tip of the abdomen projects. This marks the black spot which is noted in the tense itching area which is quite white unless bacterial infection starts up inflammation.

The swelling is about the size of a small pea by the end of five or six days. Ulceration is the usual termination of the infection if untreated and such ulcers may be very intractable or form a favorable soil for infection with the tetanus bacillus. Quiros has estimated that 250 deaths from tetanus occurred in Costa Rica in 4 years from infection of nigua (sand flea) ulcerations.

Well-made shoes are most important in prophylaxis and the best treatment is to enucleate the egg-distended flea with a needle and then touch the cavity with pure carbolic acid followed by neutralization with alcohol. It is astonishing how expert the natives become in dissecting out these insects.

TROPICAL IMPETIGO

Under the designation pemphigus contagiosus Manson describes a very common skin disease of the tropics. The condition, however, is not pemphigus. A bacteriological examination shows in the smear great numbers of pus cells containing phagocytized diplococci. Wherry has named the organism _Diplococcus pemphigi contagiosi_. As a matter of fact, culturally, this organism is the common _Staphylococcus pyogenes aureus_.

It is also a matter of common observation that this organism when in pus cells of active inflammatory processes shows a diplococcus morphology rather than a staphylococcal one.

These staphylococcal lesions which do not start in the hair follicles are often designated as “pyoses.”

The disease is markedly contagious in children and is strikingly autoinoculable so that unless the first lesion is taken in hand immediately the eruption may become generalized. A small spot of erythema first appears which rapidly becomes vesicular, the bleb covering the entire spot, so that there is practically no surrounding inflammatory areola.

The diaphanous covering rubs off with the slightest touch and leaves underneath a raw-looking surface which extends peripherally to form an angry-looking red patch an inch or more in diameter. In adults it rarely affects parts other than the axilla or crotch.

The general health of the child is practically unaffected.

The usual treatment is with bichloride lotions followed by a dusting powder of equal parts of boric acid, starch and zinc oxide. I have found, however, that an ointment of ammoniated mercury, 2% to 5% according to age, is the most satisfactory treatment.

_Tropical Boils._—It is interesting that the same organism responsible for this more fulminating lesion should be the one responsible for the common cosmopolitan boil and in fact boils are exceedingly common in the tropics. These boils may be larger and with a greater tendency to widespread distribution and in some regions they are so common as to have a regional designation (Nile boils). The staphylococcus of tropical impetigo seems to have greater virulence than that of the boils. Autogenous vaccines are often most successful in the treatment of boils.

PIEDRA

This is a fungus disease of the hairs in which small nodules form along the shaft. They are about the size of the nits of head lice but more or less surround the hair instead of projecting off at an angle as do the ovoid lice nits. These little masses are black in color and very hard, hence the name piedra—stone. The disease is chiefly found in Colombia and is thought to be due to the application, by the women, of a mucilaginous preparation to their hair. If an infected hair be examined in liquor potassae the nodule will be found to be made up of faceted bodies matted to the side of or, at times, encircling the hair. These bodies are the spores of _Trichosporum giganteum_.

Besides piedra there are also other nodular affections of the hairs due to species of _Nocardia_. Chalmers has recently reported several cases of trichonocardiasis where the axillary hairs were matted together and the skin of the region inflamed. Castellani called attention to this condition in 1911 and reported a narrow, bacillus-like fungus as the cause, _Nocardia tenuis_. The nodules are rather soft and may be yellow, black or red in color. Microscopical examination shows the fungus.

Chalmers had excellent results by treating the affected hairs with a 2% formalin solution in alcohol. At night a 2% ointment of sulphur was applied. A 5% alcoholic solution of salicylic acid has also been recommended.

[Illustration: FIG. 133.—Insects in which the larval stage is important. (1) _Chrysomyia macellaria_; (2) larva; (3) _Dermatobia cyaniventris_ larva, early stage (ver macaque); (4) _D. cyaniventris_ larva, later stage (torcel or berne); (5) _D. cyaniventris_; (6) _Auchmeromyia luteola_; (7) _A. luteola_, larva; (8) _Sarcophaga magnifica_; (9) _S. magnifica_ larva; (10) _Anthomyia pluvialis_; (11) _A. pluvialis_ larva.]

CUTANEOUS MYIASES

=Ver Macaque.=—The best known of these myiases is that due to the larva of a botfly (Oestridae), _Dermatobia cyaniventris_.

The larva is at first club shaped and in this stage is called ver macaque. Later on it becomes worm shaped and is then called torcel in Venezuela or berne in Brazil. The natives of most of the countries where the infection is found have called the larvae “mosquito worms” or “gusano de zancudo” and they have even incriminated large mosquitoes belonging to the genus _Psorophora_ as being responsible for the infections.

Surcouf has noted that these fly larvae have been found cemented to mosquitoes of the genus _Janthinosoma_ by a glue-like substance. These mosquitoes are vicious biters and evidently the young larvae escape from the eggs attached to the mosquito and enter the wound made by the biting parts of the mosquito. Some have thought that _D. cyaniventris_ deposits its eggs in a glue-like material on the leaves of plants and that they stick to mosquitoes flying about such plants. From the facts that these eggs apparently only become attached to this particular mosquito, and further in that the eggs are attached in a constant manner with the hatching end outward, it would seem that the mother fly must in some way seize the mosquito and deposit her eggs on it. As the larva grows in the subcutaneous tissues of man or other animals a tumor-like swelling develops with a central orifice, toward which the posterior extremity of the larva points and through which it takes air into its spiracles.

It has been stated that the eggs of _D. cyaniventris_ may be conveyed by ticks.

The swelling somewhat resembles a blind boil and may be as large as a pigeon’s egg.

These botfly boils tend to break down and discharge a sero-purulent fluid and it is supposed that the larva, when mature, escapes as a result of the disintegration of the tumor.

In Brazil they make tobacco juice applications which cause the larva to protrude and then squeeze it out. The injection of a little chloroform into the larva with a hypodermic syringe, prior to its extraction with a forceps, makes the process less painful.

=The Screw Worm.=—This is the larva of a bluebottle fly, _Chrysomyia macellaria_, which differs from the common bluebottle fly, _Lucilia_, by having 3 black lines on scutum. This muscid fly lays 200 to 300 eggs in wounds or orifices having offensive discharges, as from nose, ears, etc. The larvae burrow into the adjacent tissues and cause frightful destruction of all soft parts. The mature larvae are a little more than ⅔ inch long and have circlets of spines around each of the 12 segments.

This infection is especially common in tropical and subtropical America and is important in animals as well as man.

In Yount’s 23 cases 18 were of nasal myiasis; the mortality for the 23 cases was 15% and for the nasal ones 22%. Irrigation with chloroform water or a 5% carbolic acid or compound cresol solution gives the best results in treatment. If the larvae reach the sinuses it may be necessary to open them to get at the parasites.

CREEPING ERUPTION

This is a skin affection which is also called larva migrans on account of its being due to the burrowing of more or less undetermined fly larvae in the subcutaneous tissues. In their advance, which is at the rate of from one to several inches daily, they leave a raised pinkish line. The burrow is approximately ⅙ inch in diameter. The disease is most common in Southern Russia but is also found in Africa, Asia and South America. Looss considers that hookworm larvae, when penetrating the skin, may produce similar lesions.

[Illustration: FIG. 134.—Wing venation of Diptera. _A_, first posterior cell; _B_, discal mid cross-vein; a, auxiliary vein; _C_, marginal cell; _D_, submarginal cell. In the illustration of the Chrysops wing, the letter “B,” indicating the discal cell, is misplaced. It should be in the same relative position as in the Tabanus wing.]

TUMBU FLY DISEASE

This African myiasis is due to the penetration of thighs or buttocks by the larvae of _Cordylobia anthropophaga_. The appearance of the tumefied area is quite similar to that of the tumor of _Dermatobia cyaniventris_ and the treatment is similar.

CRAW-CRAW

This is a rather chronic papular skin disease which is reported from the west coast of Africa. These papules may be as large as a small pea and are quite hard. They are found chiefly on legs and arms. The proximal lymphatic glands may be enlarged.

[Illustration: FIG. 135.—Markings of breathing slits on posterior stigmata of various larvae. 1. _Musca domestica_, showing both stigmata; 2. _Calliphora vomitoria_; 3. _Stomoxys calcitrans_; 4. _Auchmeromyia luteola_; 5. _Cordylobia anthropophaga_; 6. _Sarcophaga magnifica_.]

Undoubtedly many of the cases called craw-craw are scabies. In fact the Africans give the name to a host of different skin affections. O’Niel thought he had found a filarial larva in one of his cases and Nielly incriminated a nematode larva of the Anguillulidae family. The cause is unknown and the disease very intractable to treatment.

SECTION VII

TROPICAL DISEASES OF DISPUTED NATURE OR MINOR IMPORTANCE

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