[[[Midland Naturalist/Volume 01/Parasites of Man (5)|Continued from page 297]].]
The few nematoid parasites that remain to be considered comprise
several rare end interesting species, and likewise two of the commonest intestinal worms. What I have incidentally advanced respecting the strange way in which the old writers confounded Guinea-worms with the serpents, finds noteworthy confirmation in the circumstance that the great strongyloid kidney-worm has also been looked upon as a species of venomous ophidian reptile, acta of this order, if duly weighed, inevitably cause us to modify our interpretation of the statements made in ancient records. Thus, to return to the Guinea-worm. Whatever good the theosophical remedies recommended and enforced by Moses may have accomplished for the human victims suffering from the attacks of "fiery serpents," or Dracunculi, it is to be feared that no similar remedial measures of the mystified kind could be rendered available in the case of animals bitten by parasites that have been regarded as renal serpents. It is fortunate, indeed, for man that the great kidney-worm (Eustrongylus gigas) has only once been detected in
the human body. If this formidable entozoan, capable of attaining
length of three feet, were as common in man as it is in certain animals, no doubt the superstitions people of southern climes would readily invoke clerical aid in view of obtaining miraculous cures. Possibly a mitigation of their sufferings might follow such exhibitions of human sympathy and trust. The case of animals, however, is very different. The unfortunate wolves of the Pyrenees cannot, of course, he expected to secure any very large amount of sympathy; nevertheless, it is the business and duty of the helminthologist to point to the causes of the sufferings of all kinds of animals, whether wild or domesticated, and so far as lies in his power to suggest the means whereby their sufferings may be mitigated. Not only do solitary and large nematoid parasites take up their abode in essentially vital organs of the body, and thus secure the slow destruction of the host, but the minutest forms of the same group of entozoa frequently occur in sufficiently prodigious numbers to sweep off their victims by hundreds or even by thousands. Animal epizottics
due to this source have hitherto been little studied.
Larve.—The embryos are vermiform, and measure about the 1/165 of an inch in length. In their higher larval state they have been recognised as filarise (F. cystica.)
Intermediate Host.—From the anatomical observations of Schneider and Leuckart, it would seem that the immature worms dwell chiefly in freshwater fishes. Thus, the so-called Filaria cystica must be regarded as an immature Eustrongylus gigas. Hitherto, this little worm has been found occupying cysts or capsules, situated immediately beneath the peritoneal membrane in Galaxias scriba, and in certain oceanic fishes belonging to the genus Synbranchus. According to the eminent piscicologist, Müller, the Galariidæ present strong affinities to the Salmonidæ, but Cuvier considered them as essentially modified pikes (Esocidæ.)
Experiments—Balbiani attempted to rear Eustrongyli by direct experiment. He administered the ova to dog, but obtained only negative results. Similarly, his experiments on reptiles and fishes failed.
Remarks.—It the conclusions of Schneider and Leuckart be correct—and these make it appear that we must hold certain freshwater fishes as responsible media of infection—one can only express surprise that man is so seldom victimised by this parasite. The Syanranchi, being tropical fishes, can have little part in the infection of animals apart from seals. One must suppose that pumas, dogs, wolves, gluttons, raccoons, minks, weasels, and other carnivora contract this worm by attacking, capturing, and devouring fishes at times when they are prevented from obtaining other and more readily accessible kinds of food. How this parasite should in some instances gain access to herbivorous animals is not so clear.
Lit.—All standard works, and
especially Leuckart's. One of the most remarkable memoirs quoted by Davaine is that of Clamorgan. In this old writers work, "La Chasse de Loup," dated 1583, the kidney-worms, or Eustroagyll of modern writers, are characterised as "serpents and highly venomous beasts."
Remarks. This small viviparous entozoon, hitherto only twice encountered in the human body, is doubtless identical with Strongylus longevaginatus. The original specimen was discovered by Trentler in Germany, in 1791; the second being found by Dr. Jortsits, in Transylvania, many years afterwards (1845,) The males measure half an inch and the females rather more
than an inch in length.
Larvæ:.—Although the history of the development of the young
worms has not actually been ascertained, it is tolerably certain that the structural characters they exhibit, and the changes they undergo, are similar to those of other closely allied species. Thus, without doubt, the tree embryos are rhabditiform, and pass their larval lifetime in water, mud, and moist earth, After having undergone one or more changes of skin, attended with growth, they are possibly transferral to the human stomach.
Intermediate host—It is not certain that any intermediary bearer is necessary.
Remarks.— Water drinkers in tropical climates readily become the victims of this parasite, either by swallowing the free swimming larvae, or water insects containing the larvæ in a state of rest. The Dochmius duodenalis was discovered by Dubini, at Milan, in 1838, and its clinical importance in relation to the so-called Egyptian chlorosis was first announced by Griesinger. We now know that this destructive little parasite is a fertile cause of the wasting disorders of tropical countries generally: the affections termed tropical anæmia or hypoæmia being especially prevalent in the West Indies, in Cayenne, in Brazil, in Egypt, and in the Comoren Islands lying to the north-east of Madagascar. The worms are veritable bloodsuckers, behaving like leeches; probably, however, the loss of strength and diminution of vital power which they occasion is not so much due to the actual amount of blood abstracted as to the severe irritation resulting from the injuries they inflict upon the mucous membrane of the infested intestine.
Lit.—The Work of Leuckart; and especially a Memoir by Wucherer in Deutsches Archiv fur Klinische Meidicin}, Sept. 27, 1872, (s. 379—400.)
[To be continued.]
This work was published before January 1, 1930, and is in the public domain worldwide because the author died at least 100 years ago.
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↑Communicated by Mr. Hughes to the Microscopical Section of the Birmingham Natural History and Microscopical Society, November 19th, 1878 On Dr. Cobbold's behalf, Mr, Hughes exhibited a slide showing male and female examples of the destructive parasite (Dochmius duodenalis) which causes the Egyptian chlorosis.
