Further reports (no. 5) on flies as carriers of infection.

Date:
1912
Catalogue details

Licence: In copyright

Credit: Further reports (no. 5) on flies as carriers of infection. Source: Wellcome Collection.

    12/30 (page 8)
    witli decomposing organic matter, and its larvse may be met with in ditches containing sewage, in tubs of liquid manure in gardens, and in similar situations. The chief characteristic of the larvte of species of Eristalis, which is also exhibited by those belonging to allied genera, is the prolongation of the hinder end of the body to form a long, extensile tail, at the end of which are situate the apertures of the two main respiratory trunks, this arrangement enabling the larva to breathe atmospheric air while its body is buried in mud several inches below the surface of the Avater. It is this peculiarity that has gained for the larvae of Eristalis and its allies the popular designation “ liat-tailed Maggots.” The larva of the Drone-Fly is a fat, whitish, semi- translucent grub, measuring when adult at least three quarters of an incli in length exclusive of the tail, which, when fully extended, may measure two and a half inches or more. On the ventral surface certain of the body-segments are provided with protrusible pro-legs, which assist the larva in its movements. During* some tour weeks in September and October, 1907, a number of larvae of the Drone-Fly were passed per rectum by a woman in Hampshire, who had recently arrived from France, where she had eaten a considerable quantity of watercress. According to the statement of Dr. H. McQuade, Fling Lodge, Totton, Hants, who forwarded specimens for identification to Mr. S. G. Shattock, Hoyal College of Surgeons, by whom they were submitted to the author,—twenty or thirty larvae (? pupae) “without any tail” were first passed, and “after few days interval others came singly—all Avith tails.” As was only to be expected, the appearance of the larvae had thrown the patient into a “ dreadful state of fear,” but it was stated that otherwise she had “ suffered no inconvenience.” The statement as to the previous consumption of watercress by the patient would in this case seem to afford a reasonable explanation of the origin of the larvae, though, if this hypothesis be correct, the conditions under Avhich the watercress was grown must have been decidedly unsatis- factory. It is noteworthy that the larvae were observed for about four weeks, and that those first passed had apparently already assumed the pupal state, so that the total time during which larvae were present in the patient’s intestine was in all probability considerably longer than the period during which they were actually seen. It is of course possible that successive infestations may have taken place; this is indeed rendered probable by the fact that the specimens submitted to the author, which were passed on October 1, included a pupa as well as two adult larvae, and that the pupae (?) first seen had been passed some three weeks earlier. In March, 1865, a case someAvhat similar to the foregoing occurred at Fulda, in Germany,—also in a woman. In this instance some half-dozen living larvae Avere voided on March 5th, as the result of the administration of a dose of rhubarb to the patient, Avho believed herself troubled by intestinal aaoiius. Dr. B. Wagner, by Avliom the case is recorded,(“) gives reasons for thinking that the eggs from Avhich these larvae originated must have been swallowed by the patient with polluted drinking water. From one of the larvae thus discharged a male fly Avas duly bred