Chapter XVII: Section III: NEMATODA (Round Worms) (5)

_Ascaris lumbricoides_, Linneus.--This common parasite was for a long while regarded as identical with the great lumbricoid of the horse, but the question has been finally settled by Schneider, who has shown that the human worm, although identical with Dujardin’s _Ascaris suilla_ of the hog, is nevertheless quite distinct from the _Ascaris megalocephala_ of solipeds. The large lumbricoid occasionally found in the ox belongs to the human worm. Our large human helminth resembles the common earth-worm in general appearance only. The males usually measure from four to six inches in length, and the females from ten to fourteen inches. Some have been reported up to seventeen or eighteen inches in length. The body is smooth, fusiform, and elastic, and marked by numerous fine transverse rings. It is attenuated towards either extremity, the anterior end terminating in a prominently three-lobed mouth The tail is bluntly pointed. The female is much shorter than the male, having a diameter of nearly a quarter of an inch. The male is supplied with a double spiculum, its tail being always more or less curved towards the central surface. The female reproductive orifice is situated above the centre of the body. According to Schneider, the tail supports from 138 to 150 caudal papillæ, that is, from 69 to 75 on either side of the median line. Below the anus the papillæ are regularly arranged in pairs, seven in number, the two uppermost pairs being double.

Notwithstanding the advantage which the size of this entozoon affords us in the matter of observation and experiment, we are yet ignorant as to the precise mode in which the young gain access to the human body. From what has been said respecting the quick growth of _Ascaris mystax_ in the dog, and from what has been observed respecting the rapid growth of the so-called _A. suilla_ in the hog, we know that the worm requires but a short time to pass from the larval to the sexual state. The view of Hering, Mosler, Davaine, and others, who suppose that these worms are reared in a direct manner by swallowing the ova, is, as Leuckart observed, not yet proved. We are not in full possession of the facts of larval development. It is true that Professor Heller’s interesting “find” has shown that when these worms first gain access to the human body their size is quite insignificant. At the post mortem of an imbecile, Heller discovered eighteen young worms, varying in size from about 1/9″ to 1/2″ in length (2·75 to 13 mm.). The sexes were indistinguishable. As a set-off against this, Leuckart’s repeated attempts to rear _Ascaris lumbricoides_ and _A. mystax_ by means of direct feeding-experiments with the eggs all failed. Thus, we are yet left in doubt as to the destiny of the larvæ during the period which elapses between the time of their escape from the egg and the time of their entry into the human body. So important is the question as to the mode of origination, growth, and subsequent development of the larvæ, that it may be well to trace, however briefly, what steps have been taken to clear up the matter. Leuckart obtained his negative results by the administration of ripe ova to dogs, rabbits, swine, and mice. The eggs of _Ascaris lumbricoides_ have been kept alive by Dr Davaine for a period of more than five years. I have myself watched the development of their contents in fresh water through all the stages of yolk segmentation up to the stage of an imperfectly-organised, coiled, intra-chorional embryo, and have kept them in the latter condition for a period of three months. According to Davaine (‘Comptes Rendus,’ 1858, p. 1217), the fully-developed embryo is cylindrical, its length being, 1/100th of an inch. The mouth is not furnished with the three characteristic papillæ of the genus, and the tail terminates suddenly in a point. Davaine administered some of his five-year-old embryos to rats, and had the satisfaction of finding a few of these eggs in the rodent’s fæces, with their embryos still living, but striving to emerge. He also gave eggs to a cow, and introduced others into the stomachs of dogs in small linen-covered flasks. As a general result it may be said that the embryos escaped from their shells. Those eggs, however, in which the yolk-segmentation had not arrived at the early embryonal stage remained unaffected. According to Heller, the embryo of _A. lumbricoides_ casts its first skin while still within the egg, and “a subsequent ecdysis probably completes its definitive form” (l. c., s. 615). So far back as 1853 Verloren reared coiled intra-chorional embryos in the eggs of _Ascaris marginata_ within a period of fifteen days in distilled water. I also reared the embryos of this species in fresh water, and kept them alive for a period of nearly a year and a half, at the expiration of which time, and during the warm weather, some few of them succeeded in making their escape. According to Davaine, the eggs of many nematode species will readily retain their vitality though long exposed to dryness, but their yolk-contents will not go on developing during this period of exposure. As regards _A. mystax_, however, Heller remarks that whilst “the eggs have a great power of resisting external influences, their development is not arrested in spirits of wine, chromic acid, or oil of turpentine” (l. c., s. 631). In the case of _Ascaris tetraptera_ of the mouse, embryonic formation goes on in spite of the absence of external moisture. Davaine has noticed the same thing in the oxyurides of rodents. Dryness does not even destroy the eggs of _A. lumbricoides_ and _Trichocephalus dispar_. It would seem, in short, that the eggs of nematodes which normally take up their residence in cats, dogs, and in the carnivora which reside in arid regions, will develop embryos in the egg without external moisture. As before remarked, Davaine thinks it is not necessary that these nematode embryos should pass through any intermediary bearer, and he believes that they are often directly transferred to the stomach of their “hosts” whilst adhering in the form of an impalpable dust to the coats of their bearers, whence they are detached by the animal’s frequent habit of licking the fur. Davaine’s view has received some support from the observations and experiments of Unterberger with the eggs of _Ascaris maculosa_. This observer administered eggs of the worm to doves (whose fæces were free of eggs), and seventeen days after found ova in the fæces.

With the eggs of the _Ascaris megalocephala_ of the horse I performed numerous experiments. I reared the embryos in simple fresh water, and found them during warm weather escaping before the expiration of five months. I also succeeded in rearing these larvæ in pond mud, noticing, at the same time, that after their escape from the shell they grew more or less rapidly up to a certain point, after which they ceased growing. The addition of horses’ dung to soft wet mud in one case, and of cows’ dung in another, neither appeared to advance nor retard the process of embryonal formation, so long as the embryos were enclosed in their shells. On the other hand, when I reared embryos in simple horse-dung purposely kept moist, they attained a higher degree of organisation than did those in wet mud or water. Having watched hundreds of these larvæ under varying conditions, I came to the conclusion that, after escape from the egg, their activity, growth, and strength was most marked when they occupied media which happened to be impure. Davaine experimented on cows, and Leuckart also experimented on horses, with the eggs of this worm without success. Leuckart also failed to rear the larvæ in intermediary hosts. Some eggs passed through the water-palmer unaltered.

These results, so far as they go, seem to be borne out by facts of a professional order. Thus, an instance has been brought under my notice where a considerable number of peasants and their children, dwelling in a parish in Yorkshire, were infested with this worm. There was, in short, a local endemic helminthiasis. Through the parish runs a stream which supplies the cottagers with all the water they employ for domestic purposes (washing, drinking, and so forth). Some of the peasants living by the side of the stream keep pigs, and the sewage from this source has been allowed to pass into the stream itself. Now, if Schneider’s determination as to the identity of the lumbricoid of man and the pig is correct (which I do not doubt), the explanation of the cause of the endemic becomes a very simple matter. But it does not explain all that we desire to know about the young worms. Either the freed embryos before they enter the human bearer accomplish further changes of form and growth in the sewage or impure water; or, what is far less probable, they pass into the bodies of intermediary hosts (such as insect-larvæ, Gammari, Entomostraca, &c.) to undergo the necessary changes. Practically, no doubt, it comes to the same thing in the end. Even if we suppose that the _Ascaris suilla_ and _A. lumbricoides_ are not identical species, still it is evident that any person discharging the eggs of lumbricoids in the vicinity of open waters becomes, by that fact, a source and centre of infection. To ensure an endemic it is probably only further necessary that the human inhabitants should employ the contaminated water for domestic purposes. But time and an increase of temperature must be allowed for the bringing about of those known and unknown larval changes that alike form the necessary antecedents of infection. In this connection I will only add, that if the present position of the question be such as I have here represented it to be, we see that Mosler was not far wrong when he suggested that “contamination of the drinking water with the eggs out of privies is to be blamed” as a source of infection. According to Heller, from whom I quote, Mosler actually demonstrated the presence of the eggs in water thus exposed. In like manner it becomes obvious that Davaine’s practical remark (although it was based on the assumption of a direct infection by the eggs), that filtration will probably be sufficient to prevent infection, loses nothing of its hygienic value.

The foregoing observations naturally lead one to the question of frequency and distribution. Davaine holds that the comparative infrequency of this parasite in Paris is due to the free use of the filter. In London, though not uncommon, the worm rarely occurs in great numbers in one bearer. Those cases in our hospitals, where considerable numbers have been present, have usually come up from suburban or country places. Heller states that these worms were found in 9·1 per cent. of post mortems conducted at Dresden, in 12 per cent. at Erlangen, and in 17 per cent. at Kiel. He quotes Huss as stating that no one is free from this worm in Finland. The prevalence of large round worms in warm countries generally is well known. Throughout India and the East they are extremely abundant, and the same may be said of the West Indies, Brazil, and the adjacent territories. Professor Dyce and others have remarked on the extreme prevalence of lumbrici in the Mauritius, but they are comparatively rare along the sea border. In all situations where there is an abundant fresh-water supply these parasites are particularly common, as in the lowlands of Holland and the lake districts of Sweden. The abundance of water is certainly not alone sufficient to explain the frequency of the parasite, seeing that the most important factor is that which rests upon the uncivilised habits of the rural population. What, therefore, it may be asked, can be the cause of immunity enjoyed by Icelanders in this respect? The answer is not apparent; nevertheless Krabbe and Finsen have testified to the fact that Iceland is the only country that is entirely free from _Ascaris lumbricoides_.

As remarked in my previous work the number of worms present in any human bearer is usually small, varying commonly from one to six or eight. Cases in which scores or hundreds have existed are comparatively rare. Küchenmeister mentions the case of one child who passed 103 examples, and of another child that harbored from 300 to 400 worms. Dr Gilli, of Turin, gives a case where 510 were passed by a child, and Cruveilhier estimated that over 1000 existed in an idiot girl, whose intestines he found crammed with them. A remarkable case has also been communicated to me by Dr Mackeith, of Sandhurst, Kent, who, by means of santonine, expelled from a little girl, five and a half years of age, 300 lumbrici; and I am likewise indebted to Dr Cooper Rose for notes of a case in which about thirty lumbrici were expelled, chiefly in consequence of the employment of this drug. The most interesting fact, however, in this case was that the child was only fifteen months old. In this case the symptoms were severe.

The proper habitat of the lumbricus is the upper and middle part of the small intestine. From this situation it often wanders into the stomach, and frequently gains access to the outer world, not only by the natural passages of the mouth, nostrils, and anus, but also, occasionally, in a more direct way, by perforating the intestinal and abdominal walls. Many cases are on record where lumbrici have passed into the abdominal cavity. In other instances they have lodged themselves within the abdominal viscera and pulmonary organs. When they find their way into the parietes of the abdomen and adjacent parts, they usually give rise to the formation of abscesses requiring surgical interference.

As regards the symptoms produced by lumbrici, these vary according to the situation they happen to occupy. The symptoms are also modified by age and temperament. In the stomach and intestines they give rise to colic and shooting pains about the abdomen, followed generally by dyspepsia, nasal itching, nausea, vomiting, and even diarrhœa. Occasionally death supervenes suddenly. A singular case of this kind (the particulars of which I only gathered from a local newspaper) occurred in a boy, thirteen years of age, at the County Gaol at Hertford, in 1873. From Dr Evans’s statement, made at the coroner’s inquest, the sole cause of death appeared to be due to pressure on the windpipe by a worm lodged in the gullet. Sometimes there is cerebral disturbance, attended with general restlessness and convulsive twitchings during sleep. Thus, Dr Woodman has recorded a serious case of convulsions arising from lumbricoid worms, in which, however, a cure was effected by expulsion of the worms. An anonymous writer in the ‘Medical Gazette’ records a case of epilepsy from this cause, whilst another writer in the same journal (1839) mentions an instance where two lumbrici and one tapeworm were associated in the production of similar phenomena. But a much more striking case is also given (anonymously) in the ‘Gazette’ for 1874 (p. 415), where a single lumbricus caused the bearer to be a lunatic for eight years. The victim suffered from cataleptic fits, which lasted for two or three weeks at a time. M. Petrequin, in his ‘Traité Pratique,’ records two cases of amaurosis in young girls produced by lumbrici. A fatal case is recorded by Petrenz, where 200 worms produced enteritis, and another fatal case is given by Roger from perforation (1848). Cases of perforation are also given by Young, by Blair (1861), by Mondière (1839), by Buchner (1851), by Sheppard (1861), and by Luschka (1854), the worms in this last-mentioned case occupying the cavity of the pleura. Cases of severe irritation affecting the genito-urinary organs are given by Dreyfus, Buckingham, and others; and one or two instances are reported where these worms have been discharged from several parts of the body (Neilson, 1833). I may add that the third fasciculus of a work illustrating the collection of morbid anatomy in the Army Medical Museum at Chatham gives a case of lumbrici occupying the biliary ducts and gall-bladder. I find, moreover, two additional cases of perforation of the small intestine, one of which appeared in the ‘London Medical Gazette’ (1827) and the other in the ‘Lancet’ (1836).

During the Franco-German war Dr Reginald Pierson, as he afterwards informed me, removed a lumbricus from an abscess formed in the abdominal parietes of a soldier. But amongst the most curious cases (illustrating the wandering habits of these parasites) are those severally described by Barwell (1857), Williams, Prichard, and the Messrs Stockbridge. In Barwell’s case an Ascaris was expelled from a child who had swallowed the brass “eye” of a lady’s dress. Through the circular loop of this eye, used as a toy, the Ascaris had partly thrust its body, and becoming thus strangulated, it probably perished before it was evacuated. In Prichard’s case (1859) one or two lumbrici had similarly trapped themselves in the eyes of buttons swallowed by the patient, and one worm, not contented with a single strangulation, had succeeded in passing its body through two buttons. In 1842 Mr T. G. Stockbridge gave a similar case, in which he, not inaptly, spoke of these “hooks and eyes” as constituting a new remedy or “worm-trap” for lumbricus, and singularly enough, a namesake (W. Stockbridge), in the succeeding year, also recorded a like instance of the “mechanical expulsion of worms” by metallic buttons. Again, a third correspondent in the ‘Boston Journal,’ under the initials A. M., spoke of an open-topped thimble as constituting another new “worm-trap,” whilst he gave a case of lumbrici penetrating “metallic suspensor buttons.” There is also the case reported by Williams, who, at a meeting of the Boston Society for Medical Improvement, exhibited “a lumbricus with a dress-hook attached” (1857). Lastly, another lumbricus, trapped in the same way, may be seen in the Museum of the Royal College of Surgeons at Edinburgh.

Owing to the presence of a peculiar irritating vapour which is given out by these lumbricoids, particularly when fresh, several observers have experienced curious symptoms. Thus, Miram on two occasions, when examining _A. megalocephala_, was attacked with sneezing, excessive secretion of tears, with swelling of the puncta lacrymalia, and Huber also experienced a troublesome itching of the hands and neck after examining specimens of _A. lumbricoides_. In like manner I have myself had watery suffusion of the eyes (when collecting the perivisceral fluid for Marcet’s analyses: see Bibliog.), and Bastian has given a detailed account of the serious effects which the poison produced upon him. In Bastian’s case even spirit specimens produced irritation. The attacks of catarrh and asthma were so persistent and severe that they lasted for six weeks at a time. So sensitive was Bastian to the lumbricoid-miasm that he could not even put on a coat that he had worn during his investigations without experiencing fresh attacks of sneezing and other catarrhal symptoms. The attacks became periodical, occurring between five and six in the morning, being accompanied by dyspnœa and a distressing spasmodic cough. Bastian, in short, was quite a martyr in the cause of nematode anatomy.

BIBLIOGRAPHY (No. 34).--_Abousson, L._, “On the Presence of Worms (lumbrici) in the Air-passages,” from ‘Arch. Gén. de Méd.,’ in ‘Med.-Chir. Rev.,’ 1836.--(Anonymous), _A. M._, “Another New Worm-trap--an open-topped Thimble in the Nostril (also notice of metallic suspender buttons penetrated by Lumbrici),” ‘Bost. Med. and Surg. Journ.,’ vol. xxvii, p. 121, 1842-43; see also T. G. and W. Stockbridge.--(Anon.), “Lumbrici expelled by Bismuth,” ‘Bost. M. and S. Journ.’ (from ‘Gaz. des Hôp.,’ ‘Journ. des Connaiss. Méd.,’ and ‘Boletin del Inst.-Med.-Valenc.’), 1859.--(Anon.), “Case of one Tapeworm and two Lumbrici causing Epilepsy,” from ‘Bull. du Midi’ and ‘Gaz. Méd.,’ 1839.--(Anon.), “Case of Perforation of the Ileum by Ascarides,” from ‘Hufl. and Ossan’s Journ.,’ in the ‘Lancet,’ 1836.--(Anon.), “Case of Lumbrici in the Biliary the Ducts and Gall-bladder,” note and fig. in third fasc., illust. the Coll. of Morb. Anat. in the Army Med. 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Wissensch.,’ 1852 (“Anat.,” s. 755).--_Davaine_, in his ‘Traité,’ l. c., 2nd edit., syn. xcvii, and p. 122-235 (with details of forty-five cases); see also his memoir “On the Development and Propagation of the _Trichoceph. dispar_ and _A. lumbricoides_,” from ‘Comptes Rendus,’ in ‘Ann. Nat. Hist.,’ vol. ii, 3rd series, 1858; also in the ‘Journ. of Pract. Med. and Surg.,’ Eng. edit., vol. i, 1858, and in the ‘Veterinarian,’ vol. xxxii, p. 700, 1859, from ‘Proc. of Acad. des Sci.,’ in ‘Bost. M. and S. Journ.,’ vol. lix, p. 157, 1858-59.--_Idem_, art. “Entozoaires,” in ‘Dict. de Méd. et Chir. prat.’--_David, J. B._, “Cases of Perforation of the Intestines by Worms,” from ‘Gaz. Méd. de Paris,’ in ‘Dubl. Med. Press,’ 1840, p. 223.--_Diesing_, ‘Syst. Helm.,’ ii, p. 166; and in ‘Revis der Nemat.,’ l. c., s. 660.--_Douglas, J._, “Worms (Lumbrici) evacuated at an Ulcer of the Groin,” ‘Med. Ess. and Obs.,’ vol. i, 2nd edit. 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Comment.,’ vol. viii, 1783.--_Kirkland_, “Case of Lumbricus in an Abscess of the Liver,” rep. in his book, entitled ‘An Enquiry,’ vol. ii, p. 186 (quoted by Richter and Davaine), London, 1786.--_Küchenmeister_, ‘Manual,’ Eng. edit., p. 410-427.--_Leidy, J._, ‘Proc. Acad. Phil.,’ 1856, p. 50.--_Lente, F. D._, “Lumbricus in the Stomach causing Dyspnœa,” in his “Rep. of Cases occurring in the New York Hosp.,” in ‘New York Journ. of Med.,’ vol. v, new series, p. 167, 1850.--_Lettsom_, “Case of Lumbricus evacuated from an Abdominal Abscess,” ‘Trans. Med. Soc. Lond.,’ and ‘Lond. Med. Repos.,’ 1817.--_Leuckart_, l. c., s. 152-258.--_Lieberkühn_, in ‘Miller’s Arch.’ (“Anat. of _A. suilla_”), 1855, s. 331.--_Luschka_, “Case of Lumbrici within the Pleura,” from ‘Virch. Arch.,’ in ‘Med.-Chir. Rev.,’ 1854.--_Lowne, B. T._, “The Anatomy of the Round Worm,” ‘Trans. Roy. Micr. Soc.,’ 1871, p. 55.--_Maesson_, “On a Worm found in the Bubo of a Woman 36 years of age;” see ‘Entozoa and Parasites, being a ref. to numerous papers;’ from “Valentin’s Repertorium,” in ‘Month. Journ. of Med. Sci.,’ vol. ii, p. 559, 1842; also in ‘Micr. Journ. and Struct. Rec.,’ p. 85, 1842.--_Marcet, W._, “Chemical Exam. of the Fluid from the Peritoneal Cavity of _A. megalocephala_,” ‘Proc. Roy. Soc.,’ 1862, No. 72, p. 69.--_Martin, D. T._, “Large number of Worms (140 examples of _A. lumbricoides_) discharged from a Child five years old,” rep. from the “Stethoscope,” in ‘Bost. Med. and Surg. Journ.,’ vol. xliv, p. 301, 1851.--_Mattei, R._, “On a Case of two Lumbricoid Worms, which had penetrated during life into the liver, and were demonstrated by Prof. G. Pelizzari to his pupils in the Sch. of Path. Anat. of Florence,” from ‘Gaz. Med. Ital. Toscana,’ in ‘Dubl. Quart. Journ.,’ vol. xxiv, 1857.--_Michel_, “Case of Epilepsy in a Girl ten years of age, caused by Lumbrici,” from ‘Journ. des Connaiss. Méd.,’ in ‘Amer. Journ. of Med. Sci.,’ vol. vi, p. 451, 1843.--_M’Laggan, J._, “Gangrenous Sore from a large Worm in the Parietes of the Abdomen,” ‘Med. Comment.,’ vol. ii, 1774, p. 80.--_Molin_, in ‘Sitzungsb. d. k. Akad.,’ 1859, s. 23.--_Mondière_, “On Perforation by Worms (three cases),” from ‘L’Expérience,’ in ‘Med.-Chir. Rev.,’ 1839.--_Moore, E. D._, “Example of _A. lumbr._ ejected by the Mouth,” ‘Prov. Med. and Surg. Journ.,’ 1852.--_Morgan, J._, “Case of Perforation of the Stomach, probably by a (Lumbricus) Worm,” ‘Lancet,’ 1836.--_Morland, W. W._, “Ejection of numerous Lumbrici from the Mouth, impaction of the small intestine with Lumbrici, (of which 365 were removed post mortem),” ‘Bost. M. and S. Journ.,’ vol. lvi, 1857.--_Idem_., an “_A. lumbr._ of unusual size (over 17 inches long),” ‘Rep. of Bost. Soc. for Improv.,’ in ‘Bost. M. and S. 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