William A. (William Albert) Riley.

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tion that the contamination occurred outside of the body. They
have been supposed to be the cause of dysentery, or diarrhoea, and
it is probable that the Acarus dysenteric? 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-shell 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 Japanese 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 classed as an accidental parasite.


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, repre-
senting 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, Ch&techelyne vesuviana and
Stigmatogaster subterraneus.

Myriapoda 133

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 canal of a child.

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

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 appetite, nausea and vomiting. The latter had been partic-
ularly pronounced for three days, when there was discovered in the
midst of the material expelled a living myriapod of the species
Ch&techelyne vesuviana. Ant helminthics 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

One of the extreme cases on record is that reported by Shipley
(1914). Specimens of Geophilus gorizensis (= G. subterraneus)
'were vomited and passed 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 canal."

"According to her attendant's statements these centipedes had
left the body in some hundreds during a period of twelve or eighteen
months. Their presence produced vomiting and some hsematemesis,
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

134 Accidental or Facultative Parasites

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-shell is very tough and if the eggs had been swallowed
the egg-shells 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 indica-
tions as to the manner of infestation. It is possible that the myria-
pods have been taken up in uncooked fruit or vegetables.


Scholeciasis Hope (1837) brought together six records of infesta-
tion 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 butterfly, Pieris brqssicce. 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.


Canthariasis By this term Hope designated instances of acci-
dental 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.

Dipterous Larva

Larva of Piophila casei. Caudal aspect of larva.
Posterior stigmata.

In one of these cases upwards of 1200 larvae and several perfect
insects were said to have been passed per anum. 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 Dermestidce
(larder beetles et a/.) or
Tenebrionida (meal infesting species) . Infestation probably occurs
through eating raw or imperfectly cooked foods containing eggs or
minute larvae of these insects. Hf

Brumpt cites a curious case of accidental parasitism by a coleopter-
ous 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.


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
multitude of cases on
record, relating to com-
paratively few species.
The literature of the sub-
ject, like that relating
to facultative parasitism
in general, is unsatis-
factory, for most of the

determinations Of Species 99. Piophila casei. After Graham-Smith.

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

136 Accidental or Facultative Parasites

determined. Fortunately, several workers have undertaken com-
parative studies along this line. The most comprehensive publica-
tion is that of Banks (1912), entitled "The structure of certain dip-
terous 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 button"
and without a chitinous ring surrounding the three slits; the slits narrowly
or broadly oval, not bent (fig. 171 i). A caly pirate muscidce and some species
of Anthomyiida. 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-


c. Integument leathery and usually strongly spinulose; larvae hypodermatic or

endoparasitic Bot flies (fig. 171, f, g, k). Oestridce

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 of the stigma not complete; open ventro-mesally,

button absent (fig. 171 e) Flesh flies. Sarcophaga

dd. Stigmata not in a pit.

e. The chitin ring open ventra-mesally ; button absent (fig. 171 c). Screw-

worm fly Chrysomyia

ee. The chitin ring closed.

/. Slits of the posterior stigmata straight; marginal "button" present (fig. 171 b);
two distinct mouth hooks, fleshy tubercles around the anal area. Phormia
(fig. 171 f), Lucilia and Calliphora (fig. 172, a, b), Protocalliphora (fig. 171, j),
Cynomyia (fig. 171, a). Blow flies, bluebottle flies Calliphorina

Dipterous Larva 137

Jf. Slits of the posterior stigmata sinuous or bent. Subfamily Muscinse.
g. Slits of the posterior stigmata bent; usually two mouth hooks. Muscina
stabulans (fig. 171, /), Muscina similis, Myiospila meditatunda (fig. 172, i),
and some of the higher Anthomyiida.

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 calcitrant) the horn fly (Lyperosia irritans), Pyrellia, Pseudo-
pyrellia, Morellia, Mesembrina. Polietes, et. al. (fig. 172 in part).

Eristalis The larvae of Eristalis are the so-called rat-tailed mag-
gots, which develop in foul water. In a few instances these larvae
have been known to pass through the human alimentary canal
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 treat-
ment 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 canal, the excrement was mixed with blood and she
suffered from vertigo and severe headaches. During the four fol-
lowing 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 through-


Accidental or Facultative Parasites

100. Fannia canicularis (x4). After Graham-Smith.

out almost its entire length was marked by bloody 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 com-

monly reported of dip-
terous larvae causing intes-
tinal myasis . Hewitt
(1912) has presented a
valuable study of the bio-
nomics and of the larva&
f these flies, a type of
what is needed for all the
species concerned in my-

^ We have SCCQ tWO

cases of their having been
passed in stools, without having caused any special symptoms,
In other instances their presence in the alimentary canal 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, bloody diarrhoea.

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
passing 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 chroriic. The
appetite was variable, there was a bad taste in the mouth, tongue
furred and ridged, and red at the edges. Her complexion was sal-
low, and general nervousness was marked. As treatment, there
were given doses of magnesium sulphate before breakfast and at

A nthyomyndcz


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 passed 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.
The case was complicated by various other disorders, but the
symptoms given above seem to be in large part attributable to the
myasis. There is nothing in the case to justify the assumption
that larvae were continuously present, for years. It seems more
reasonable to suppose that something in the habits of the patient
favored repeated infestation. Nevertheless, a study of the various
cases of intestinal myasis caused by these and
other species of dipterous larvae seems to indi-
cate that the normal life cycle may be con-
siderably prolonged under the unusual conditions.
The best authenticated cases of myasis of the
urinary passage have been due to larvae of
Fannia. Chevril (1909) collected and described
twenty cases, of which seven seemed beyond
doubt. One of these was that of a woman of
fifty-five who suffered from albuminuria, and
urinated with much difficulty, and finally passed
thirty to forty larvae of Fannia canicularis.

It is probable that infestation usually occurs
through eating partially decayed fruit or vege-
tables on which the flies have deposited their
eggs. Wellman points out that the flies may
deposit their eggs in or about the anus of
persons using outside privies and Hewitt
believes that this latter method of infection is probably the common
one in the case of infants belonging to careless mothers. "Such
infants are sometimes left about in an exposed and not very clean
condition, in consequence of which flies are readily attracted to them
and deposit their eggs."

Muscinae The larvae of the common house-fly, Musca domestica,
are occasionally recorded as having been passed with the feces or
vomit of man. While such cases may occur, it is probable that in
most instances similar appearing larvae of other insects have been
mistakenly identified.

101. Larva of Fannia


Accidental or Facultative Parasites

102. Muscina stabulans (x4). After Graham

Muscina stabulans is re-
garded by Portschinsky
(1913) as responsible for
many of the cases of intesti-
nal myasis attributed to other
species. He records the case
of a peasant who suffered from
pains in the lower part of the
breast and intestines, and
whose stools were mixed with
blood. From November until
March he had felt particu-
larly ill, being troubled with
nausea and vomiting in addi-
tion to the pain in his intestines. In March, his physician prescribed
injections of a concentrated solution of tannin, which resulted in the
expulsion of fifty living larvae of Muscina stabulans. Thereafter
the patient felt much better, although he suffered from intestinal
catarrh in a less severe form.

Calliphorinae Closely related to the Sarcophagidae are the
Calliphorince. to which grflup belong many of the so-called "blue
bottle" flies. Their larvae feed upon dead animals, and upon fresh
and cooked meat. Those of Pro-
tocalliphora, already mentioned,
are ectoparasitic on living nestling i ^aSp*K&

birds. Larva? of Lucilia, we have l^^PHI^S^F

taken from tumors on living turtles.
To this sub-family belongs also
Aucheromyia luteola, the Congo
floor maggot. Some of these,
and at least the last mentioned,
are confirmed, rather than faculat-
tive parasites. Various species of
Calliphorinae are occassionally met
with as facultative parasites of

Chrysomyia macellaria, the screw worm fly (fig. 107), is the fly
which is responsible for the most serious cases of human myasis in
the United States. It is widely distributed in the United States

103. Lucilia caesar, (xa). After Howard.

Chrysomyia macellaria



but is especially abundant in the south. While the larvae b:
decaying matter in general, they so commonly breed in the living
flesh of animals that they merit rank as true parasites. The females
are attracted to open wounds of all kinds on cattle and other animals
and quickly deposit large numbers of eggs. Animals which have
been recently castrated, dehorned, or branded, injured by barbed
wire, or even by the attacks of ticks are promptly attacked in the
regions where the fly abounds. Even the navel of young calves or
discharges from the vulva of cows may attract the insect.

Not infrequently the fly attacks man, being attracted by an of-
fensive breath, a chronic catarrh, or a purulent discharge from the
ears. Most common are the cases where the eggs are deposited in


104. Calliphora erythrocephala, (x6). After Graham-Smith.

the nostrils. The larvae, which are hatched in a day or two, are
provided with strong spines and proceed to bore into the tissues
of the nose, even down into or through the bone, into the frontal
sinus, the pharynx, larynx, and neighboring parts.

Osborn (1896) quotes a number of detailed accounts of the attacks
of the Chrysomyia on man. A vivid picture of the symptomology
of rhinal myasis caused by the larvae of this fly is given by Castellani
and Chalmers: "Some couple of days after a person suffering from
a chronic catarrh, foul breath, or ozaena, has slept in the open or has
been attacked by a fly when riding or driving, i.e., when the hands
are engaged signs of severe catarrh appear, accompanied with
inordinate sneezing and severe pain over the root of the nose or the
frontal bone. Quickly the nose becomes swollen, and later the face
also may swell, while examination of the nose may show the presence


Accidental or Facultative Parasites

of the larvae. Left untreated, the patient rapidly becomes worse,
and pus and blood are discharged from the nose, from which an
offensive odor issues. Cough appears as well as fever, and often
some delirium. If the patient lives long enough, the septum of the
nose may fall in, the soft and hard palates may be pierced, the wall
of the pharynx may be destroyed. By this time, however, the course
of the disease will have become quite evident by the larvae dropping
out of the nose, and if the patient continues to live all the larvae
may come away naturally."

For treatment of rhinal myasis these writers recommend douch-
ing the nose with chloroform water or a solution of chloroform in
sweet milk (10-20 per cent), followed by douches of mild antiseptics.
Surgical treatment may be necessary.

105. Larva of a flesh fly (Sarcophaga) .1 Caudal aspect. Anterior stigmata. Pharyngeal skeleton.

Sarcophagidae The larvae (fig. 105) of flies of this family usually
feed upon meats, but have been found in cheese, oleomargerine,
pickled herring, dead and living insects, cow dung and human feces.
Certain species are parasitic in insects. Higgins (1890) reported
an instance of ''hundreds" of larvae of Sarcophaga being vomited by a
child eighteen months of age. There was no doubt as to their origin
for they were voided while the physician was in the room. There
are many other reports of their occurrence in the alimentary canal.
We have recorded elsewhere (Riley, 1906) a case in which some ten
or twelve larvae of Sarcophaga were found feeding on the diseased
tissues of a malignant tumor. The tumor, a melanotic sarcoma,
was about the size of a small walnut, and located in the small of the
back of an elderly lady. Although they had irritated and caused a
slight hemorrhage, neither the patient nor others of the family knew


of their presence. Any discomfort which they had caused had been
attributed to the sarcomatous growth. The infestation occurred

106. Afleshfly (Sarcophaga), (x4). After Graham-Smith.

Online LibraryWilliam A. (William Albert) RileyHandbook of medical entomology → online text (page 12 of 30)