(d) Living in subcutaneous tissue (Cordylobia, Dermatobia, Bengalia (?), Hypoderma).
(e) Passing through the alimentary canal (Fannia, Musca, Eristalis, Syrphus, Gastrophilus).
In the above list, only the more common genera producing myiasis are mentioned. In England, Type (e) is fairly common, and Types (b) and (c) are occasionally observed.’
We may now consider in detail, but very shortly, the categories set forth by Dr. Graham-Smith:—
(a) The very peculiar blood-sucking maggot known as the Congo-floor-maggot—the larva of Auchmeromyia luteola—fortunately does not spread beyond tropical and sub-tropical Africa. It chiefly affects the natives who sleep on mats.
(b) The flies which deposit their ova and larvae in the cavities of the body are again mostly foreign. The worst of all is the screw-worm (Chrysomyia macellaria) of the Southern States, Central and South America. Although it extends to Canada it is not troublesome north of Texas.
Occasionally, blow-flies in Great Britain deposit their ova in the human nose or ear. They very rapidly hatch and cause great inflammation and necrosis until they can be discharged or removed. They have even been found in the anterior chamber of the eye; and I have some microscopic sections showing the presence of these larvae in that chamber, whither they had probably proceeded from the nasal sinuses. But on the whole, cases of this sort are comparatively rare, and cause but little trouble.
(c) The real difficulty, and one which late last summer proved a serious trouble to our army in the field, are the cases in which maggots were found in neglected wounds. Here, however, we may take some comfort in the fact that the trouble is fortunately much greater in the tropical and sub-tropical regions than in more temperate climates, and diminishes as the cold weather draws on. Still, during the hot weeks of last August there were cases of wounded soldiers left lying on the fields for two or three days who were found to be suffering in this way. One almost hesitates to offer suggestions to our heroes in such cruel conditions; but whenever and wherever it can be done wounds should as far as possible be kept covered.
Not only are neglected wounds affected, but tumours and ulcers are often attacked. But, as I have said, the danger is much greater in warmer climates. We know that Herod Agrippa ‘was eaten of worms, and gave up the ghost’: a fact which recalls the translation given by an undergraduate in difficulties with the Acts of the Apostles in the ‘Little-Go’ who rendered ‘καì γενóμενος σκωληκóβρωτος ἐξέψυξεν’ ‘He became a Skolekobrote, and died in the enjoyment of that office.’
(d) Flies burrowing in the subcutaneous tissues are again very much commoner in tropical climates than in Northern Europe, and the cases quoted in our country are comparatively rare.