Handbook of Medical Entomology Part 15

In the nose, the myriapods have been known to live for months and according to some records, even for years. The symptoms caused by their presence are inflammation, with or without increased flow of mucus, itching, more or less intense headache, and at times general symptoms such as vertigo, delirium, convulsions, and the like. These symptoms disappear suddenly when the parasites are expelled.

In the intestine of man, myriapods give rise to obscure symptoms suggestive of infestation by parasitic worms. In a case reported by Verdun and Bruyant (1912), a child twenty months of age had been affected for fifteen days by digestive disturbances characterized by loss of appet.i.te, nausea and vomiting. The latter had been particularly p.r.o.nounced for three days, when there was discovered in the midst of the material expelled a living myriapod of the species _Chaetechelyne vesuviana_. Anthelminthics had been administered without result. In some of the other cases, the administration of such drugs had resulted in the expulsion of the parasite through the a.n.u.s.

One of the extreme cases on record is that reported by Shipley (1914).

Specimens of _Geophilus gorizensis_ (= _G. subterraneus_) "were vomited and pa.s.sed by a woman of 68 years of age. Some of the centipedes emerged through the patient's nose, and it must be mentioned that she was also suffering from a round worm. One of her doctors was of the opinion that the centipedes were certainly breeding inside the lady's intestines, and as many as seven or eight, sometimes more, were daily leaving the alimentary ca.n.a.l."

"According to her attendant's statements those centipedes had left the body in some hundreds during a period of twelve or eighteen months.

Their presence produced vomiting and some haematemesis, and treatment with thymol, male-fern and turpentine had no effect in removing the creatures."

The clinical details, as supplied by Dr. Theodore Thompson were as follows:

"Examined by me July, 1912, her tongue was dry and glazed. There was bleeding taking place from the nose and I saw a living centipede she had just extracted from her nostril. Her heart, lungs and abdomen appeared normal. She was not very wasted, and did not think she had lost much flesh, nor was there any marked degree of anemia."

Shipley gives the following reasons for believing it impossible that these centipedes could have multiplied in the patient's intestine. "The breeding habits of the genus _Geophilus_ are peculiar, and ill adapted for reproducing in such a habitat. The male builds a small web or nest, in which he places his sperm, and the female fertilizes herself from this nest or web, and when the eggs are fertilized they are again laid in a nest or web in which they incubate and in two or three weeks hatch out. The young _Geophilus_ differ but very little from the adult, except in size. It is just possible, but improbable, that a clutch of eggs had been swallowed by the host when eating some vegetables or fruit, but against this is the fact that the _Geophilus_ does not lay its eggs upon vegetables or fruit, but upon dry wood or earth. The egg-sh.e.l.l is very tough and if the eggs had been swallowed the egg-sh.e.l.ls could certainly have been detected if the dejecta were examined. The specimens of the centipede showed very little signs of being digested, and it is almost impossible to reconcile the story of the patient with what one knows of the habits of the centipedes."

In none of the observed cases have there been any clear indications as to the manner of infestation. It is possible that the myriapods have been taken up in uncooked fruit or vegetables.

LEPIDOPTEROUS LARVae

SCHOLECIASIS--Hope (1837) brought together six records of infestation of man by lepidopterous larvae and proposed to apply the name scholeciasis to this type of parasitism. The clearest case was that of a young boy who had repeatedly eaten raw cabbage and who vomited larvae of the cabbage b.u.t.terfly, _Pieris bra.s.sicae_. Such cases are extremely rare, and there are few reliable data relative to the subject. In this connection it may be noted that Spuler (1906) has described a moth whose larvae live as ectoparasites of the sloth.

COLEOPTERA

CANTHARIASIS--By this term Hope designated instances of accidental parasitism by the larvae or adults of beetles. Reports of such cases are usually scouted by parasitologists but there seems no good basis for wholly rejecting them. Cobbold refers to a half dozen cases of accidental parasitism by the larvae of _Blaps mortisaga_. In one of these cases upwards of 1200 larvae and several perfect insects were said to have been pa.s.sed _per annum_. French (1905) reports the case of a man who for a considerable period voided adult living beetles of the species _Nitidula bipustulata_. Most of the other cases on record relate to the larvae of _Dermestidae_ (larder beetles _et al._) or _Tenebrionidae_ (meal infesting species). Infestation probably occurs through eating raw or imperfectly cooked foods containing eggs or minute larvae of these insects.

[Ill.u.s.tration: 98. Larva of Piophila casei. Caudal aspect of larva.

Posterior stigmata.]

Brumpt cites a curious case of accidental parasitism by a coleopterous larva belonging to the genus _Necrobia_. This larva was extracted from a small tumor, several millimeters long, on the surface of the conjunctiva of the eye. The larvae of this genus ordinarily live in decomposing flesh and cadavers.

DIPTEROUS LARVae

[Ill.u.s.tration: 99. Piophila casei. After Graham-Smith.]

MYASIS--By this term (spelled also myiasis, and myiosis), is meant parasitism by dipterous larvae. Such parasitism may be normal, as in the cases already described under the heading parasitic Diptera, or it may be facultative, due to free-living larvae being accidentally introduced into wounds or the body-cavities of man. Of this latter type, there is a mult.i.tude of cases on record, relating to comparatively few species. The literature of the subject, like that relating to facultative parasitism in general, is unsatisfactory, for most of the determinations of species have been very loose. Indeed, so little has been known regarding the characteristics of the larvae concerned that in many instances they could not be exactly determined. Fortunately, several workers have undertaken comparative studies along this line. The most comprehensive publication is that of Banks (1912), ent.i.tled "The structure of certain dipterous larvae, with particular reference to those in human food."

Without attempting an exhaustive list, we shall discuss here the more important species of Diptera whose larvae are known to cause myasis, either external or internal. The following key will serve to determine those most likely to be encountered. The writers would be glad to examine specimens not readily identifiable, if accompanied by exact data relative to occurrence.

_a._ Body more or less flattened, depressed; broadest in the middle, each segment with dorsal, lateral, and ventral fleshy processes, of which the laterals, at least, are more or less spiniferous (fig.

101). _Fannia_ (= _Homalomyia_).

In _F. canicularis_ the dorsal processes are nearly as long as the laterals; in _F. scalaris_ the dorsal processes are short spinose tubercles.

_aa._ Body cylindrical, or slender conical tapering toward the head; without fleshy lateral processes (fig. 105).

_b._ With the posterior stigmata at the end of shorter or longer tubercles, or if not placed upon tubercles, then not in pit; usually without a "marginal b.u.t.ton" and without a chitinous ring surrounding the three slits; the slits narrowly or broadly oval, not bent (fig.

171 i). _Acalyptrate muscidae_ and some species of _Anthomyiidae_. To this group belong the cheese skipper (_Piophila casei_, figs. 98, 99), the pomace-fly (_Drosophila ampelophila_), the apple maggot (_Rhagoletis pomonella_), the cherry fruit fly (_Rhagoletis cingulata_), the small dung fly (_Sepsis violacea_, fig. 170), the beet leaf-miner (_Pegomyia vicina_, fig. 171 i), the cabbage, bean and onion maggots (_Phorbia_ spp.) et. al.

_bb._ Posterior stigmata of various forms, if the slits are narrowly oval (fig. 171) then they are surrounded by a chitin ring which may be open ventro-mesally.

_c._ Integument leathery and usually strongly spinulose; larvae hypodermatic or endoparasitic. Bot flies (fig. 171, f, g, k).--_Oestridae_

_cc._ Integument not leathery and (except in _Protocalliphora_) spinulae restricted to transverse patches near the incisures of the segments.

_d._ The stigmal plates in a pit; the lip-like margin of the pit with a number of fleshy tubercles; chitin ring of the stigma not complete; open ventro-mesally, b.u.t.ton absent (fig. 171 e). Flesh flies.--_Sarcophaga_

_dd._ Stigmata not in a pit.

_e._ The chitin ring open ventra-mesally; b.u.t.ton absent (fig. 171 c).

Screw-worm fly. _Chrysomyia_

_ee._ The chitin ring closed.

_f._ Slits of the posterior stigmata straight; marginal "b.u.t.ton" present (fig. 171 b); two distinct mouth hooks, fleshy tubercles around the a.n.a.l area. _Phormia_ (fig. 171 f), _Lucilia_ and _Calliphora_ (fig.

172, a, b), _Protocalliphora_ (fig. 171, j), _Cynomyia_ (fig. 171, a). Blow flies, bluebottle flies. _Calliphorinae_

_ff._ Slits of the posterior stigmata sinuous or bent. Subfamily Muscinae.

_g._ Slits of the posterior stigmata bent; usually two mouth hooks.

_Muscina stabulans_ (fig. 171, l), _Muscina similis_, _Myiospila meditabunda_ (fig. 172, i), and some of the higher _Anthomyiidae_.

_gg._ Slits of the posterior stigmata sinuous; mouth hooks usually consolidated into one. The house-fly (_Musca domestica_ fig. 171, d), the stable fly (_Stomoxys calcitrans_), the horn fly (_Lyperosia irritans_), _Pyrellia_, _Pseudopyrellia_, _Morellia_, _Mesembrina_.

_Polietes_, et. al. (fig. 172 in part).

_Eristalis_--The larvae of _Eristalis_ are the so-called rat-tailed maggots, which develop in foul water. In a few instances these larvae have been known to pa.s.s through the human alimentary ca.n.a.l uninjured.

Hall and Muir (1913) report the case of a boy five years of age, who had been ailing for ten weeks and who was under treatment for indigestion and chronic constipation. For some time he had vomited everything he ate. On administration of a vermifuge he voided one of the rat-tailed maggots of _Eristalis_. He admitted having drunk water from a ditch full of all manner of rotting matter. It was doubtless through this that he became infested. It is worth noting that the above described symptoms may have been due to other organisms or substances in the filthy water.

_Piophila casei_, the cheese-fly (fig. 99), deposits its eggs not only in old cheeses, but on ham, bacon, and other fats. The larvae (fig. 98) are the well-known cheese skippers, which sometimes occur in great abundance on certain kinds of cheese. Indeed, some people have a comfortable theory that such infested cheese is especially good. Such being the case, it is small wonder that this species has been repeatedly reported as causing intestinal myasis. Thebault (1901) describes the case of a girl who, shortly after consuming a large piece of badly infested cheese, became ill and experienced severe pains in the region of the navel. Later these extended through the entire alimentary ca.n.a.l, the excrement was mixed with blood and she suffered from vertigo and severe headaches. During the four following days the girl felt no change, although the excretion of the blood gradually diminished and stopped. On the fourth day she voided two half-digested larvae and, later, seven or eight, of which two were alive and moving.

That these symptoms may be directly attributed to the larvae, or "skippers," has been abundantly shown by experimental evidence.

Portschinsky cites the case of a dog fed on cheese containing the larvae.

The animal suffered much pain and its excrement contained blood. On _post mortem_ it was found that the small intestine throughout almost its entire length was marked by b.l.o.o.d.y bruises. The papillae on these places were destroyed, although the walls were not entirely perforated.

In the appendix were found two or three dead larvae. Alessandri (1910) has likewise shown that the larvae cause intestinal lesions.

According to Graham-Smith, Austen (1912) has recorded a case of myasis of the nose, attended with a profuse watery discharge of several weeks duration and pain, due to the larvae of _Piophila casei_.

ANTHYOMYIIDae--The characteristic larvae of two species of _Fannia_ (= _Homalomyia_ or _Anthomyia_, in part) (fig. 101) are the most commonly reported of dipterous larvae causing intestinal myasis. Hewitt (1912) has presented a valuable study of the bionomics and of the larvae of these flies, a type of what is needed for all the species concerned in myasis.

We have seen two cases of their having been pa.s.sed in stools, without having caused any special symptoms. In other instances their presence in the alimentary ca.n.a.l has given rise to symptoms vaguely described as those of tapeworm infestation, or helminthiasis. More specifically, they have been described as causing vertigo, severe headache, nausea and vomiting, severe abdominal pains, and in some instances, b.l.o.o.d.y diarrha.

[Ill.u.s.tration: 100. Fannia canicularis (4). After Graham-Smith.]

One of the most striking cases is that reported by Blankmeyer (1914), of a woman whose illness began fourteen years previously with nausea and vomiting. After several months of illness she began pa.s.sing larvae and was compelled to resort to enemas. Three years previous to the report, she noticed frequent shooting pains in the rectal region and at times abdominal tenderness was marked. There was much mucus in the stools and she "experienced the sensation of larvae crawling in the intestine."

Occipital headaches were marked, with remissions, and constipation became chronic. The appet.i.te was variable, there was a bad taste in the mouth, tongue furred and ridged, and red at the edges. Her complexion was sallow, and general nervousness was marked. As treatment, there were given doses of magnesium sulphate before breakfast and at 4 P. M., with five grain doses of salol four times a day. The customary parasiticides yielded no marked benefit. At the time of the report the patient pa.s.sed from four to fifty larvae per day, and was showing some signs of improvement. The nausea had disappeared, her nervousness was less evident, and there was a slight gain in weight.