Handbook of Medical Entomology Part 14

The effect of the bite of fleas on man varies considerably according to the individual susceptibility. According to Patton and Cragg, this was borne out in a curious manner by the experiments of Chick and Martin.

"In these, eight human hosts were tried; in seven, little or no irritation was produced, while in one quite severe inflammation was set up around each bite." Of two individuals, equally accustomed to the insects, going into an infested room, one may be literally tormented by them while the other will not notice them. Indeed it is not altogether a question of susceptibility, for fleas seem to have a special predilection for certain individuals. The typical itching wheals produced by the bites are sometimes followed, especially after scratching, by inflammatory papules.

The itching can be relieved by the use of lotions of carbolic acid (2-3 per cent), camphor, menthol lotion, or carbolated vaseline. If forced to sleep in an infested room, protection from attacks can be in a large measure gained by sprinkling pyrethrum, bubach, or California insect powder between the sheets. The use of camphor, menthol, or oil of eucalyptus, or oil of pennyroyal is also said to afford protection to a certain extent.

In the Eastern United States the occurrence of fleas as household pests is usually due to infested cats and dogs which have the run of the house. We have seen that the eggs are not attached to the host but drop to the floor when they are laid. Verrill, cited by Osborn, states that on one occasion he was able to collect fully a teaspoonful of eggs from the dress of a lady in whose lap a half-grown kitten had been held for a short time. Patton and Cragg record seeing the inside of a hat in which a kitten had spent the night, so covered with flea eggs that it looked "as if it had been sprinkled with sugar from a sifter." It is no wonder that houses in which pets live become overrun with the fleas.

One of the first control measures, then, consists in keeping such animals out of the house or in rigorously keeping them free from fleas.

The latter can best be accomplished by the use of strong tar soap or Armour's "Flesope," which may be obtained from most druggists. The use of a three per cent solution of creolin, approximately four teaspoonfuls to a quart of warm water, has also been recommended. While this is satisfactory in the case of dogs, it is liable to sicken cats, who will lick their fur in an effort to dry themselves. Howard recommends thoroughly rubbing into the fur a quant.i.ty of pyrethrum powder. This partially stupifies the fleas which should be promptly swept up and burned.

He also recommends providing a rug for the dog or cat to sleep on and giving this rug a frequent shaking and brushing, afterwards sweeping up and burning the dust thus removed.

Since the larvae of fleas are very susceptible to exposure, the use of bare floors, with few rugs, instead of carpets or matting, is to be recommended. Thorough sweeping, so as to allow no acc.u.mulation of dust in cracks and crevices will prove efficient. If a house is once infested it may be necessary to thoroughly scrub the floors with hot soapsuds, or to spray them with gasoline. If the latter method is adopted, care must be taken to avoid the possibility of fire.

To clear a house of fleas Skinner recommends the use of flake naphthalene. In a badly infested house he took one room at a time, scattering on the floor five pounds of flake naphthalene, and closed it for twenty-four hours. It proved to be a perfect and effectual remedy and very inexpensive, as the naphthalene could be swept up and transferred to other rooms. Dr. Skinner adds, "so far as I am concerned, the flea question is solved and if I have further trouble I know the remedy. I intend to keep the dog and cat."

The late Professor Slingerland very effectively used hydrocyanic acid gas fumigation in exterminating fleas in houses. In one case, where failure was reported, he found on investigation that the house had become thoroughly reinfested from pet cats, which had been left untreated. Fumigation with sulphur is likewise efficient.

The fact that adult fleas are usually to be found on the floor, when not on their hosts, was ingeniously taken advantage of by Professor S. H.

Gage in ridding an animal room at Cornell University of the pests. He swathed the legs of a janitor with sticky fly-paper and had him walk back and forth in the room. Large numbers of the fleas were collected in this manner.

In some parts of the southern United States hogs are commonly infested and in turn infest sheds, barns and even houses. Mr. H. E. Vick informs us that it is a common practice to turn sheep into barn-lots and sheds in the spring of the year to collect in their wool, the fleas which abound in these places after the hogs have been turned out.

It is a common belief that adult fleas are attracted to fresh meat and that advantage of this can be taken in trapping them. Various workers, notably Mitzman (1910), have shown that there is no basis for such a belief.

THE TRUE CHIGGERS--The chigoes, or true chiggers, are the most completely parasitic of any of the fleas. Of the dozen or more known species, one commonly attacks man. This is _Dermatophilus penetrans_, more commonly known as _Sarcopsylla penetrans_ or _Pulex penetrans_.

This species occurs in Mexico, the West Indies, Central and South America. There are no authentic records of its occurrence in the United States although, as Baker has pointed out, there is no reason why it should not become established in Florida and Texas. It is usually believed that Brazil was its original home. Sometime about the middle of the nineteenth century it was introduced into West Africa and has spread across that continent.

The males and the immature females of _Dermatophilus penetrans_ (fig.

93) closely resemble those of other fleas. They are very active little brown insects about 1-1.2 mm. in size, which live in the dust of native huts and stables, and in dry, sandy soil. In such places they often occur in enormous numbers and become a veritable plague.

[Ill.u.s.tration: 93. Dermatophilus penetrans. Much enlarged. After Karsten.]

They attack not only man but various animals. According to Castellani and Chalmers, "Perhaps the most noted feature is the way in which it attacks pigs. On the Gold Coast it appeared to be largely kept in existence by these animals. It is very easily captured in the free state by taking a little pig with a pale abdomen, and placing it on its back on the ground on which infected pigs are living. After watching a few moments, a black speck will appear on the pig's abdomen, and quickly another and another. These black specks are jiggers which can easily be transferred to a test tube. On examination they will be found to be males and females in about equal numbers."

Both the males and females suck blood. That which characterizes this species as distinguished from other fleas attacking man is that when the impregnated female attacks she burrows into the skin and there swells until in a few days she has the size and appearance of a small pea (fig.

94). Where they are abundant, hundreds of the pests may attack a single individual (fig. 95). Here they lie with the apex of the abdomen blocking the opening. According to Fulleborn (1908) they do not penetrate beneath the epidermis. The eggs are not laid in the flesh of the victim, as is sometimes stated, but are expelled through this opening. The female then dies, withers and falls away or is expelled by ulceration. According to Brumpt, she first quits the skin and then, falling to the ground, deposits her eggs. The subsequent development in so far as known, is like that of other fleas.

[Ill.u.s.tration: 94. Dermatophilus penetrans, gravid female. After Moniez.]

[Ill.u.s.tration: 95. Chiggers in the sole of foot of man. Manson's Tropical Diseases. Permission of Ca.s.sell and Co.]

The chigoe usually enters between the toes, the skin about the roots of the nails, or the soles of the feet, although it may attack other parts of the body. Mense records the occurrence in folds of the epidermis, as in the neighborhood of the a.n.u.s. They give rise to irritation and unless promptly and aseptically removed there often occurs pus formation and the development of a more or less serious abscess. Gangrene and even teta.n.u.s may ensue.

Treatment consists in the careful removal of the insect, an operation more easily accomplished a day or two after its entrance, than at first, when it is unswollen. The ulcerated point should then be treated with weak carbolic acid, or tincture of iodine, or dusted thoroughly with an antiseptic powder.

[Ill.u.s.tration: 96. Echidnophaga gallinacea.]

[Ill.u.s.tration: 97. Echidnophaga gallinacea infesting head of chicken.

After Enderlein.]

Castellani and Chalmers recommend as prophylactic measures, keeping the house clean and keeping pigs, poultry, and cattle away therefrom. "High boots should be used, and especial care should be taken not to go to a ground floor bathroom with bare feet. The feet, especially the toes, and under the nails, should be carefully examined every morning to see if any black dots can be discovered, when the jigger should be at once removed, and in this way suppuration will be prevented. It is advisable, also, to sprinkle the floors with carbolic lotion, Jeyes'

fluid, or with pyrethrum powder, or with a strong infusion of native tobacco, as recommended by Law and Castellani."

_Echidnophaga gallinacea_ (fig. 96) is a widely distributed Hectopsyllid attacking poultry (fig. 97). It occurs in the Southern and Southwestern United States and has been occasionally reported as attacking man, especially children. It is less highly specialized than _Dermatophilus penetrans_, and does not ordinarily cause serious trouble in man.

CHAPTER IV

ACCIDENTAL OR FACULTATIVE PARASITES

In addition to the many species of Arthropods which are normally parasitic on man and animals, there is a considerable number of those which may be cla.s.sed as _accidental_ or _facultative_ parasites.

Accidental or facultative parasites are species which are normally free-living, but which are able to exist as parasites when accidentally introduced into the body of man or other animal. A wide range of forms is included under this grouping.

ACARINA

A considerable number of mites have been reported as accidental or even normal, endoparasites of man, but the authentic cases are comparatively few.

In considering such reports it is well to keep in mind von Siebold's warning that in view of the universal distribution of mites one should be on his guard. In vessels in which animal and other organic fluids and moist substances gradually dry out, mites are very abundantly found. If such vessels are used without very careful preliminary cleaning, for the reception of evacuations of the sick, or for the reception of parts removed from the body, such things may be readily contaminated by mites, which have no other relation whatever to them.

Nevertheless, there is no doubt but that certain mites, normally free-living, have occurred as accidental parasites of man. Of these the most commonly met with is _Tyroglyphus siro_, the cheese-mite.

_Tyroglyphus siro_ is a small mite of a whitish color. The male measures about 500 long by 250 wide, the female slightly larger. They live in cheese of almost any kind, especially such as is a little decayed. "The individuals gather together in winter in groups or heaps in the hollows and c.h.i.n.ks of the cheese and there remain motionless. As soon as the temperature rises a little, they gnaw away at the cheese and reduce it to a powder. The powder is composed of excrement having the appearance of little grayish microscopic b.a.l.l.s; eggs, old and new, cracked and empty; larvae, nymphs, and perfect mites, cast skins and fragments of cheese, to which must be added numerous spores of microscopic fungi."--Murray.

_Tyroglyphus siro_, and related species, have been found many times in human feces, under conditions which preclude the explanation that the contamination occurred outside of the body. They have been supposed to be the cause of dysentery, or diarrha, and it is probable that the _Acarus dysenteriae_ of Linnaeus, and Latreille, was this species.

However, there is little evidence that the mites cause any noteworthy symptoms, even when taken into the body in large numbers.

_Histiogaster spermaticus_ (fig. 152) is a Tyroglyphid mite which was reported by Trouessart (1902) as having been found in a cyst in the groin, adherent to the testis. When the cyst was punctured, it yielded about two ounces of opalescent fluid containing spermatozoa and numerous mites in all stages of development. The evidence indicated that a fecundated female mite had been introduced into the urethra by means of an unclean catheter. Though Trouessart reported the case as that of a Sarcoptid, Banks places the genus _Histiogaster_ with the Tyroglyphidae.

He states that our species feeds on the oyster-sh.e.l.l bark louse, possibly only after the latter is dead, and that in England a species feeds within decaying reeds.

_Nephrophages sanguinarius_ is a peculiarly-shaped, angular mite which was found by Miyake and Scriba (1893) for eight successive days in the urine of a j.a.panese suffering from fibrinuria. Males, .117 mm. long by .079 mm. wide, females .36 mm. by. 12 mm., and eggs were found both in the spontaneously emitted urine and in that drawn by means of a catheter. All the mites found were dead. The describers regarded this mite as a true endoparasite, but it is more probable that it should be cla.s.sed as an accidental parasite.

MYRIAPODA

There are on record a number of cases of myriapods occurring as accidental parasites of man. The subject has been treated in detail by Blanchard (1898 and 1902), who discussed forty cases. Since then at least eight additions have been made to the list.

Neveau-Lamaire (1908) lists thirteen species implicated, representing eight different genera. Of the _Chilognatha_ there are three, _Julus terrestris_, _J. londinensis_ and _Polydesmus complanatus_. The remainder are _Chilopoda_, namely, _Lithobius forficatus_, _L.

malenops_, _Geophilus carpophagus_, _G. electricus_, _G. similis_, _G.

cephalicus_, _Scutigera coleoptrata_, _Himantarium gervaisi_, _Chaetechelyne vesuviana_ and _Stigmatogaster subterraneus_.

The majority of the cases relate to infestation of the nasal fossae, or the frontal sinus, but intestinal infestation also occurs and there is one recorded case of the presence of a species in _Julus_ (fig. 13) in the auditory ca.n.a.l of a child.