Midland Naturalist/Volume 01/Parasites of Man (5)

by Thomas Spencer Cobbold

Parasites of Man.^[1]

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By T. Spencer Cobbold, M.D., F.R.S.

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[Continued from page 213.]

Considering the Importance of the new parasite (Flaria Bancrofti) it was thought advisable to devote more space than usual to the literature of the subject; consequently, the remaining species of filariform nematodes may be dismissed with comparative brevity. It happens, moreover, that much doubt hangs over the question of the genuineness of several of the forms that require to be noticed. The human strongholds, on the other hand, are all of them well defined species; and, as will be seen in the sequel, they play almost as important a role in the production of endemic disorders as do the Filaria themselves, In a general sense, the Guinea-worm may be spoken of as a Filaria, but, for reasons given in my introductory treatise and elsewhere, I prefer to consider this parasitic as the type of an osculant genus (Dracunculus,} The nematoids variously placed by helminthologists under the genera Selerostoma, Anchylostoma, Dochmius, and so forth, are all of them closely related to the Strongyli properly so called. As regards the question of nomenclature, I must leave it to Mr. Grove to say whether, in the genera above mentioned, it is permissible for us to retain the final component stoma unaltered. Many continental helminthologists no longer speak of the genera Distoma, Tristoma, Polystoma, Selerostoma, and so forth; but, following Diesing, they prefer to convert the final Greek component into a true Latin syllable. Thus we have Distomum, Polystomum, Sclerostomum, and the like. Long habit has so fully familiarised us with the old plan of retaining the Greek termination unaltered, that I confess to some reluctance in parting with the final component (stoma) although the form is not strictly classical. On the other hand, the introduction of new and more striking departures from the legitimate method of employing the binomial nomenclature is much to be deprecated. Such a barbarism as Hyperbodon butzkopf, for example—intolerable as it must sound to the scholar's ear—is, nevertheless, freely accepted by well-known Naturalists both at home and abroad. In helminthology there are probably fewer glaring errors of nomenclature than occur in other departments of Natural History science. Nevertheless, I think Mr. Grove's criticism in the matter of the family term Distomidæ perfectly just.^[2] Following the practice of the late Edward Forbes and others, I have frequently, and as I think fittingly, employed the names of savans for the purpose of forming new genera and species. Thus, by almost universal consent (on the Continent, at least) my genus Bilharzia has been adopted: its general acceptance being in part due, no doubt, to the fact that, as a generic term, it had priority over the various other titles severally proposed by Diesing, Weinland, and Moquin-Tandon.

Nematoda Continued.

28.—Filaria lentis, Diesing.

Synonymy.—Filaria oculi, Owen; F. oculi-humani, Von Nordmann.

Remarks.—This small worm was originally discovered in a case of lenticular cataract, under the professional care of the distinguished oculist Von Gräfe. Similar cases have also been recorded by Jüngken and Sickæl, by Gescheidt and Von Ammon, and by M. Fane, There is no certain evidence as to the sexual maturity of the worms obtained in these cases, although in one instance the parasite measured three-quarters of an inch in length.

Literature.—The standard works of Leuckart (I. c. Bd. 1L, s. 622,} and Davaine, (L. deuxième edit., p. 831.) and in my Entozoa, (p. 332.)

20.—Filaria labialis, Pane.

Syn.— None.

Remarks.—The original description of this species was based upon the "find" of a medical student at Naples. The worm (of which the female only is known} was an inch and a quarter in length, and occupied a pustular cavity in the upper lip.

Lit.—Quoted by Leuckart (s. 616) and Davaine, (Synops, c. VII.,) from Pane's Nota di un clininte nematoide, in Annali dell. Acend. degli aspirante Naturaliste, Napoli, 1861, (Ser. 3, Vol. IV.)

30—Fileria hominis oris, Leidy.

Syn.—None.

Remarks,—This apparently sexually immature worm was described by Prof. Leidy, from a specimen preserved in alcohol, and labelled as having been obtained from the mouth of a child. It measured five and a half inches in length.

Lit.—Leidy, J., in Proeced. Philad. Acad. Nat. Sci. for 1850, (p. 117.)

31.—Filaria trachealis, Bristowe.

Syn.—Nematoideum tracheale, Bristowe and Rainey.

Remarks.—Minute worms, each measuring about ⁠1/36⁠ of an inch, were found by Rainey in the trachea and larynx, (post mortem.) Their mature condition is unknown.

Lit.—Bristowe and Rainey, in the Path. Soc. Trans. for 1855.

32.—Filaria Loa, Guyot.

Syn.—F. oculi, Gervais and Van Beneden; F. lacrymalis, Dubini; F. medinensis, Gmelin; Dreaunculus ocali, Diesing; D. Loa, Cobbold.

Remarks.—This worm is found beneath the conjunctiva of negroes. It is rather more than 1¼in. in length; being particularly abundant in the Gaboon region of Western Africa. It has also been seen in Brazil and other countries. When the worm voluntarily quits the eye, a natural cure of the disease is thus produced.

Lit.—Fully noticed in the standard works of Leuckart, Küchenmeister, Dayaine, Moquin-Vandon, and especially Gervais and Van Beneden. The descriptions are chiefly taken from the writings of Lestrille, Guyot, and Arrachart.

33.—Draecanculus medinensis, Cobbold.

Syn.—Filaria dracunealus, Bremser; F. medinensis, Gmelin; Dracunealus, Lister; D. Persarum, Kaempfer; Furia, Modeer; Gordius, Linnæus; Vermis, Grundler.

Intermediate Host.—The Russian traveller and helminthologist Fedischenko discovered that small freshwater crustaceans, of the genus Cyclops, harbour the larvæ of the Guinea-worm. In the free embryo stage these larvæ perforate the abdominal segments, and thence proceed to coil themselves within the limbs of the crustacean bearers.

Remarks.—The Guinea-worm disease, so common in India and other Oriental countries, is undoubtedly the same disorder as the Dracontiasis of Plutarch. It corresponds also with the Israelitish endemic affection describe by Moses as due to fiery serpents. Küchenmeister's learned historical narrative leaves no room for doubt on this point. The older writers frequently confounded nematoid worms with serpents. As regards the mode of infection, there can be little doubt that the advanced larvæ of Dracunculus are swallowed with potable waters, and thus pass info the human stomach. Thence the female worms migrate to the surface of the body, in which situation they rapidly grow to maturity. The female parasite in its sexually mature state has been very fully anatomised by Professor Bastian. The embryos have likewise been carefully studied by Bastian, Busk, Carter, Fedschenko, Leuckart, Robin, Davaine, Lewis, and myself.

Lit—All standard works, especially that of Leuckart, which offers an admirable resumé of the whole subject, including an exhaustive summary of Fedscheuko's writings. Extensive literary references are given in Davaine's well-known work, and also in the Bibliography appended to my introductory treatise.

 

To be continued.

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1. Communicated by Mr. Hughes to the Microscopical Section of the Birmingham Natural History and Microscopical Society, October 15th, 1878, On Dr. Cobbold's behalf a microscopic slide was shown, containing numerous embryos of the Guinea worm, The young worms had been mounted some twenty-five years previously. They were originally taken from adult Dracunculusin the possession of the late Sir George Bullingall, of Edinburgh. Altogether the specimens had been preserved for upwards of of a century.
2. See the "Midland Naturalist" for May, p. 123.