Midland Naturalist/Volume 01/Parasites of Man (4)

by Thomas Spencer Cobbold

Parasites of Man.^[1]

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By T. Spencer Cobbold, M.D,, F.R.5,, Hon, Vice-President Of The Birmingham Natural History and Microscopical Society.

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[Continued from page 121.]

Although the twenty-four parasites already brought under the notice of the Section may be fairly regarded us exhausting the list of human trematodes and cestodes, yet several other species of tapeworm have from thine to time been indicated on what are probably insufficient grounds. In this doubtful category I place Weinland’s Taenia megaloon, and also another tapeworm which Dr. Ransome concludes to exist from the diagnostic evidence furnished by the finding and examination of a particular form of cestode ovum. In Weinland's case both loose proglottides and eggs were examined; consequently the strobile may turn out to represent a good species. Weinland figures the ova (in Zoolog. Garten Frankf., 1861, s. 118.) Respecting a variety of manifestly spurious entozaa, such as Frédault's Trachelocampula and the like, I have nothing to say.

The nematoid group of parasites, next to be considered, are probably better known than any other helminths. This arises partly on account of the excessive frequency of the little threadworm, (Oxyuris,) partly from the circumstance that the large round worm (Ascaris) bears a marked resemblance to the common lob-worm of our gardens, (Lumbricus,) and partly, or perhaps chiefly, because the spiral flesh-worm (Trichina) plays an important rôle in the production of epidemic disease (Trichinosis.) Endless mistakes have arisen from the error of confounding parasitic roundworms with earthworms, The mischievous character of unscientific or inexact knowledge may be illustrated by the fact that I have known nervous persons so seriously alarmed at the appearance of lumbricoid entozoa that they have regarded their presence as an omen of approaching dissolution. I have even known a spurious nematoid to be dreaded as "the worm that dieth not." It is very important that correct views should be entertained respecting the nature and sources of the various members of this group of parasites. Nothing is move absurd than the popular notion that nematoid entozoa, especially threadworms, (Oxyurides,) arise or make their appearance in consequence of an impoverished state or cachexia of the body of the host. This ridiculous conception, which is as old as the hills, is ever and anon re-asserted with all the pride and confidence which should only he displayed when any real and valuable discovery has to be announced, The notion, as it now stands, is a feeble remnant of the theory of equivocal generation, For the establishment of the truth of this theory the spontaneous generationists always pointed, triumphantly as they supposed, to the mode of origination of the entozoa. The truth is, neither threadworms nor heliminths of any other kind arise from diseased conditions. They often produce constitutional disturbance in their victims, this bad effect being misinterpreted as» cause of the appearance of the entozoa themselves. A healthy person is just as likely—nay, he is even more likely to entertain parasites than a feeble person, True, the strong host may suffer comparatively little, whilst the weak host succumbs to his guests. The host is the entozoan's native territory, What our native island is to us, our bodies are to parasites. To attack, to invade, to infest, is their legitimate prerogative; and for this end it must be admitted that their organisation is admirably adapted. To be sure, it is equally our prerogative to refuse the would-be guests admission, but any method of resistance likely to prove effectual must be based upon scientific conclusions resulting for the most part from experimental research: Ancient dogmas and pre-conceived opinions to often operate to obscure the mental vision, and thus prevent the adoption of measures calculated to cheek not a few of the many evils to which our common flesh is heir.

 

Nematoda.

 

25.—Trichina spiralis, Owen.

Synonymy.—Pseudolius trichina, Davaine,

Larvæ.—Commonly spoken of as muscle-trichinæ, capsuled or encysted trichina, and fleshworms.

Intermediate Most—All warm-blooded animals, especially mammals, and of these the bow and rat more especially. Man himself may become an intermediate bearer.

Experiments.—These are of two kinds, as referring either to the larvæ or to the full-grown worm. The larvæ were first reared by Herbst (1850) and the adult worms by Virchow (1859.} These results were subsequently verified and extended by Leuckart, Clans, Küchenmeister, Pagenstecher, and many others abroad; and they were confirmed by Thudichum and myself in this country. The worm-feedings administered by Prof. Simonds and myself infected four dogs, two cats, one pig, one guinea pig, one hedgehog, and probably several rats which, unfortunately, made their escape.

Remarks.—The original discovery of the capsules, as "little bodies" or "concretions," was made either by Tiedemann, (1822,) or by Peacock (1824.) Their parasite character was first indicated by Hilton (1833.) The actual discovery of the worm was first made by Paget, (1834,) and afterwards scientifically named and described by Owen (1835.) The most brilliant discovery of all was that of Zenker (1860.) He it was who demonstrated that migrating Trichinæ were productive of disease (Trichinosis.) Finally, the most complete account of the migrations and structural changes undergone by the worm are due to Leuckart.

Literature.—Althaus, Essay on Trichinosis, 1864; Boehler, Die Trichineukrankheit in Planen, 1863; Gerlach, Die Trichinen, 1844; Cobbold, On the History of the Discovery of Trichina spiralis in Supp. to "Entozoa," 1860; Idem, Experiments, Proceedings Linn. Soc., 1867; Leuckart, Untersuchungen neber T. spiralis, 1866; Luschka, Zeitschrift für Wissenseh. Zool., 1851; Owen, in Zool. Soc. Trans. 1835; Pagenstecher (and Fuchs.) Die Trichinen. 1865; Thudichum, Government Report "On Parasitic Diseases," &c., 1845; Virehow, Darstellung der Lehre yon den Trichinen (u.s.w..) 1864; Zenker, Zur Lehre von der Trichinenkrankheit, in Deutsches Archiv f. Klin. Med., Bd. VIII, and in Virchew’s Archiv., 1533.

26.—Trichecephalus dispar, Rudelphi.

Syn.—T. hominis, Goeze; Tricharis, Buttner; Asceris trichiura, Linn.

Larvæ:.—Küchenmeister and Meissner supposed that Trichinæ were the young of Trichecephalus, This view was controverted by Virehow.

Int. Host——Unknown. The experiments of Davaine render it probable that infection takes place in a direct manner some time after the eggs have escaped the human bearer.

Experiments.—Davaine finds that dryness does not destroy the ova, and that a period of six mouths elapses before embryonic formation commences. The embryos will live for many years in the freed eggs.

Remarks.—The Dublin helminthologist, Bellingham, was one of the earliest to attest the frequency of the whipworm in Great Britain, He found it in eighty-one out of ninety post mortem examinations. Davaine has stated that not less then half the Parisians ave victimised by this worm. Mr. Cooper, of Greenwich, found it present in eleven out of sixteen autopsies. Either this worm or its congener (infesting ruminants) has been anatomised by Dujardin, von Siebold, Mayer, Eberth, Erasmus Wilson, Busk, Bastian, and myself.

Lit.—Bastian, in Philos. Trans., 1866; Bellinghamm, in Dublin Journal, 1838; Busk, in Annals Nat. Hist., 1841; Cobbold, in}} Linn. Trans, 1859; Eberth, in Sieb., and Köll. Zeitsehr., 1860; Mayer, ibid, 1858-60; Siebold, in Wiegm. Archiv., 1815. Wilson, E., in The Veterinary Record and Transactions, 1816.

27.—Fiiaria Bancrofti, Cobbold.

Syn.—Filaria sanguinis hominis, Lewis; F. Wüchereri, Cobbold, (conditionally;) Filariose dermatheuica, O'Neill; Filaris sangunis, Bancroft; Trichina cystica, Salisbury.

Larvæ.— The synonyms above given all originally referred to the embryonic condition; but the embryos have also been described as nematoid hæmatozoa, micro-filariæ, hæmatochyloas helminths, (Corre.) worms of Guadeloupe, (Crevaux,) worms of Brazil, (Wüchever,) probably embryos of Stronglidæ, (Leuckart,) anguillula-like microscopic nematodes (Seusino.)

Int. Host—Dr. Lancroft originally suggested and Dr. Manson actually discovered that the hæmatazoal micro-filariæ were passively transferred to the stomach of mosquitoes. Dr. Manson has described the transformations undergone by the larvæ within these insects.

Experiments.—Dr. Manson induced an infected Chinese to sleep in a mosquito-house, and thus procured on the following morning a number of mosquitoes that had gorged themselves with blood containing human filariæ. A relatively far greater proportion of hæmatozoa existed in a drop of the insucked blood taken from the mosquito than in a drop taken from the Chinese in a direct manner. The construction of the proboscis of the female mosquito seems to be especially adapted tor drawing the worms out of the capillary blood vessels.

Remarks.—There is every reason to believe that the microscopic hæmatozoa of man are capable of producing a variety of diseases, some of which are endemic. In this category must be placed certain forms of hæmaturia, chyluria, vatix, elephantiasis, and other lymphoid affections, and likewise the African cutaneous disorder termed craw-craw. The whole of them have been characterised as constituting varieties of one disorder which Dr. Bourel-Roncière terms Wücherer's helminthiasis. The adult worm was first discovered by Bancroft and first described by myself. It was afterwards found and described by Lewis, and subsequently our "finds" were verified by Dr. Aranja and by Dr. F. dos Santos. The larvae were first discovered by Wücherer, whose observations were afterwards verified and extended by Salisbury, by myself, and especially by Lewis. Free microscopic nematoids very closely resembling these larvæ have been found in the potable waters of Rio (aqua da Carioca) by Dr. Magalbaes. Their genetic relation with F. Baxcrofti, however, is very doubtful.

Lit.—Wücherer, in Gaz. Med. da Bahia, Dec., 1868, and Sept., 1869, and in Hallise's Zeitschrift, 1869, and in Arch. de Méd. Nawale, 1870; Salisbury, in Days Amer. Journ., 1868; Cobbald, in Brit. Med. Journ. July, 1872, and in Lectures on Holminth., 1872; in B.M.J., June, 1876; in the Lancet for July and Oct., 1877; in Reports of the Proceedings of the Linnean Soc.; of the Pathological Soc.; of the Medical Society of London; in the Lancet for March; in Nature of the same month, and in the Popular Science Review for April, 1878; Leuckart, Die Mensch. Par. H., 1876; Corré, Rev. des Sci. Nat., Sept., 1872; Crevaux, De Phématuric chyteuse, &e., Paris, 1872; Silva-Lima (with Crevaux,) Mom. subre a hematuria chylosa on gordurosa, (Bahia, 1876.) and in Gaz. Mod. da Bahia, Sept. 1877, and in the Lancet for March, 1878; Fonecervines, in Robin's Lécons, 1875; Lewis, on a hæmatozooa in human blood, in Gov. Rep. for 1874, and separately (Calcutta 1871,} in Indian Annals, 1873, in Med. Press, 1873, in Lond. Med. Record (rep. by me,) 1873, in Nature, 1873, and in his memoir on the Path. significance of the nematode hætmatazoa, Calcutta, 1874; see also Lewis's recent "Remarks regarding the Hæmatozoa found in the stomach of Culex Mosquito," in Proceed. of the Asiatic Society of Bengal, for March, 1878, (p. 89); Sonsino. Richerche interno, &c., in Rend. della R. Accad. di Napoli, 1874, and in Arch. Gen. de Méd., June, 1875; Arsuio, in Arch. d. Méd, Navale, 1875; Magalliies, P. S. de, in Guz, M. da Bahie, 1877, and in O Progresso Merlico for Dec.. 1877; O'Neill, on Craw-craw. in Lancet, Feb., 1875: Bonrel-Roneière, in Arch. de Méd. Navale, March, 1878, (soc Aranjo); Manson, Report on Hæmatozoa. in the bth part of the Customs Gazette, Shanghae, 1877, and rep. in Mod. Tines and Gazette, also additional cases in M. T. and G. for March, 1878, also (in a joint communication with me) in rep. of the proceedings of the Med. Soc. of London, in the Lancet, March 30, 1878; Le Ray de Méricourt, in Appendix to Nouvelle phase de ls question relative & la nature paresitaire de la chylurie, (Déconyerte du représentant adulte de la Filsire de Wücheres,) being a translation of Silva Lima's memoir, quoted above, (Arch. da Méd. Navale, Dec. 1877.) See also translations, with additions, in the Veterinarian for Feb 1878; Aranjo, A. J. P. da S, Memoria sobre a Filariose, &c., (Bahia, 1875,) see also Bourel-Tioneitre’s analysis of and commentary upon the writings of Silva Lima and Silva Araajo in the Archives above quoted; Santos. F. dos, in Gaz. Med. da Bahia for March, 1877; Moura, J. de, Thèse de concours, 1877

[To be continued.]

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1. Read before the Microscopical Section of the Birmingham Natural History and Microscopical Society, June 18th, 1878. On Dr. Cobbold’s behalf, Mr. Hughes exhibited examples of Trichina spiralis, both ln the sexually mature and larval states (capsuled and free.) He also showed specimens of Trichocephalus dispar and T. afinis, together with their ova. As regards hæmatozoa, specimens from human blood, and also from the dog, were shown in contrast, from slides prepared and presented by Dr. Lewis, of Calcutta. A full-grown example of Piluria Bancroft and numerous larvæ were also exhibited. These were from Australia.