Since the above remarks were written I have received several communications from Dr Bancroft, and also others from Drs da Silva Lima, Araujo, Assis Sousa, Paterson, Hall, of Bahia—the two last named being English physicians in practice there. I regret that I can do little more than refer to the writings of these authors in the Bibliography below; but I may observe that Drs Paterson and Hall have ascertained that the proportion of the population of Bahia affected by Filaria is 81/2 per cent. Out of 309 persons examined, 26 had hæmatozoa, which is, roughly, one in twelve, or more strictly, 8·666 per cent.
Amongst recent memoirs that by Sir J. Fayrer, read to the Epidemiological Society on the 5th of February, 1879, deserves especial attention. In regard to its significance, I have only space to remark that, much as we may regret the little interest shown by our hospital physicians and surgeons in this subject, it is particularly gratifying to see experienced Indian officers like Sir J. Fayrer, Mr Macnamara, and Dr John Murray, coming forward both to aid and render homage to their junior colleagues in Eastern parts, who are successfully labouring to advance the cause of helminthology and scientific medicine.
In concluding this subject I may observe, that one of the greatest hindrances to the due recognition of the remarkable part played by parasites in the production of human endemics and animal epizoötics arises from the circumstance that no inconsiderable number of minute worms may infest a host without obvious injury. This immunity proves nothing. If, for example, we take the case of Trichina we find that several millions of entozoa may exist in the human, or, at all events, in the animal bearer, without producing any symptom of discomfort. In such cases it is not possible to determine the strict limits of health and disease; nevertheless, were we to double the amount of infection, the imaginary line of demarcation is at once bridged over and the parasites become acknowledged as directly responsible for grave symptoms which may even prove fatal to the bearer. Again, the relative strength and size of the infected host constitute factors that materially limit the power of the parasite for injury. Where the entozoa are of minute size, and where their injurious action is primarily due to the mechanical obstructions they set up, it is clear that the virulence of the helminthiases, or resulting diseased conditions, will mainly depend upon the number of intruders.
Another consideration of the highest value in relation to epidemiology generally, and more especially in regard to the practical question as to the best methods of stamping out parasitic plagues, is that which refers to the life-history of the entozoon itself. It must be obvious that in all cases where the intermediate host can be captured and destroyed, the life-cycle of the parasite can be broken and interrupted, and if thus broken, there is an end to the further propagation of the species. The knowledge that we have acquired by experimental research in this connection has already enabled us to set a limit upon the prevalence of certain well-known disorders, such as Trichinosis, Cestode-tuberculosis, and so forth. In the case of epizoötics, however, which are indirectly due to the action of intermediary hosts that cannot be readily captured or destroyed, then our power of arresting the disease is comparatively limited. In the present case it is probably not necessary either that a dead or living mosquito should be swallowed to insure infection; but it is necessary that the parasitic larvæ should have dwelt within the mosquito in order to arrive at the highest stage of larval growth prior to their re-entrance within the human territory. Undoubtedly, the larvæ are swallowed with potable waters. Perfect filtration before use would certainly check, if in course of time it did not totally extinguish several of the many virulent diseases that now afflict the inhabitants of warm climates.
It is with reluctance that I terminate this article, but in the closing pages of this work (Book II, Section V) I hope to add a few more particulars in reference to Lewis’s latest researches.
Bibliography (No. 23).—Araujo, A. J. P. da Silva, “Memoria sobre a Filariose,” &c., Bahia, 1875; see also ‘Arch. de Méd. Nav.,’ 1875 and 1878.—Bancroft, J., “Cases of Filarious Disease,” in ‘Pathological Soc. Trans.’ for 1878, vol. xxix, p. 407.—Bourel-Roncière, “Résumé of and Commentary upon the writings of Silva Lima, Silva Araujo, and others,” in ‘Arch. de Méd. Nav.’ for March, 1878.—Idem, “Pathologie exotique. De l’hématozoaire nématoïde de l’homme et de son importance pathogénique, d’après les travaux Anglais et Bréziliens des dernières années;” ibid., for August and Sept., p. 113–134 and p. 192–214, 1878.—Cobbold, T. S., “Discovery of the Adult Representative of Microscopic Filariæ,” ‘Lancet,’ July, 1877, p. 70.—Idem, ‘On Filaria Bancrofti,’ ibid. Oct., 1877, p. 495.—Idem, “Verification of Hæmatozoal Discoveries in Australia and Egypt,” ‘Brit. Med. Journ.,’ June, 1876.—Idem, “Obs. on Hæmatozoa,” ‘Veterinarian,’ October, 1873.—Idem, “Remarks on the Ova of another Urinary Parasite (in the paper on ‘Bilharzia’) from Natal,” ‘Brit. Med. Journ.,’ July 27th, 1872, p. 89; see also Bibl. No. 12.—Idem, “Entozoa in Relation to the Public Health” (various papers), ‘Med. Times and Gaz.,’ Jan. and Feb., 1871.—Idem, ‘Worms’ (l. c., p. 151), 1872.—Idem, “Hæmatozoa; Fresh Discoveries by Lewis,” ‘Lancet’ for Feb. 6, 1875.—Idem (brief notice), the ‘Veterinarian,’ p. 209, March, 1875.—Idem, “On the Discovery of the Intermediary Host of Filaria sanguinis hominis,” ‘Lancet,’ Jan. 12, 1878, p. 69.—Idem, “On the question of Priority of Discovery,” Rep. of Med. Soc. of Lond., in ‘Lancet,’ March 30, 1878, p. 465.—Idem, ‘Mosquitoes and Filariæ’ (explanatory note), in ‘Brit. Med. Journ.,’ March 16, 1878, p. 366.—Idem, “On the Life-history of Filaria Bancrofti, as explained by the discoveries of Wucherer, Lewis, Bancroft, Manson, Sonsino, myself, and others,” “Report of the Proceed. of the Linnean Soc.” for March 7, 1878, in ‘Pop. Science Rev.,’ April, 1878; and afterwards published in extenso in ‘Journal Linn. Soc.,’ Oct. 31, 1878.—Idem, “On Filaria Bancrofti,” in Part iv of a series of papers on the Parasites of Man, in the ‘Midland Naturalist,’ August, 1878.—Idem, “On Filaria sanguinis hominis,” in a letter to the ‘Lancet,’ July 13, 1878, p. 64.—Idem, “Filariæ and Leprosy” (case from Bancroft); ‘Lancet,’ Feb. 1, 1879.—Corré, A., “Note sur l’helminthe rencontré dans les urines hémato-chyleuses,” ‘Rev. des Sci. Nat.,’ 1872.—Cossé, “Sur l’helminthe rencontré par Wucherer et Crevaux,” &c., ‘Rev. Montpellier,’ tom. i, p. 190.—Couto, A., “These de concourso,” Bahia, 1872.—Crevaux, J., “De l’hématurie chyleuse, &c.,” 1872; also in ‘L’Union Médicale,’ 1872 (abs. in ‘Brit. Med. Journ.,’ July, 1872, p. 100); also in ‘Arch. de Méd. Nav.,’ 1874; and in ‘Journ. de l’Anat. et de la Physiol.,’ 1875 (see also Silva Lima).—Davaine, C., ‘Traité,’ 2nd edit., p. 944; ‘Hæmatozoaires,’ supp., 1877.—Fayrer, Sir J., “Filaria sang. hom.,” ‘Lancet,’ March 16, 1878, p. 376.—Idem, “Elephantiasis Arabum,” ‘Med. Times and Gaz.,’ Dec. 1, 1877, p. 588; “On the Relation of Filaria sanguinis hominis to the Endemic Diseases of India,” in the ‘Lancet,’ Feb. 8 and 15, and reprinted from the ‘Med. Times and Gazette’ (same date), 1879.—Gabb, D. H., letter in ‘Lancet,’ June 22, 1878.—Leuckart, l. c., s. 638, 1876.—Lewis, T. K., “On a Hæmatozoon in Human Blood,” ‘San. Comm. 8th Rep.,’ Calcutta, 1872; ‘Med. Press,’ 1873, p. 234; ‘Indian Ann. Med. Sci.,’ 1874; ‘Lond. Med. Rec.’ (abs. by myself in vol. i, p. 5), 1873.—Idem, “Pathological Significance of Nematode Hæmatozoa,” ‘Tenth Ann. Rep.,’ 1873, Calcutta (reprint), 1874; ‘Ind. Ann.,’ 1875.—Idem, “Remarks regarding the Hæmatozoa found in the Stomach of Culex mosquito,” ‘Proc. Asiatic Soc. of Bengal,’ March, 1878, p. 89.—Idem, “Flagellated Organisms in the Blood of Rats” (being portion of a paper on “The Microscopic Organisms found in the Blood of Man and Animals,” in ‘14th Annual Report of the San. Comm. with the Govt. of India’), in the ‘Quart. Journ. of Micr. Science,’ Jan., 1879.—Idem (published since the present article was written), “The Nematoid Hæmatozoa of Man,” ibid., April, 1879.—Lima, J. F. da Silva (with Crevaux), ‘Memoria sobre hematuria chylosa ou gordurosa des paizes quentes;’ extrahida da ‘Gazeta Medica da Bahia,’ 1876; repr. in ‘Arch. de Méd. Nav.,’ Dec., 1878 (see also Le Roy de Méricourt).—Magalhães, Pedro S. de, “Filarias em estado Embryonario, encontradas n’agua tida como potavel (agua da Carioca),” ‘O Progresso Medico,’ Dezembro, 1877, p. 57.—Idem, “Nota sobre os nematoides encontrados no sedimento deposito pela agua (potavel) da Carioca,” ‘O Prog. Med.,’ 1 de Setemb., 1878, p. 577.—Idem, “Caso de filariose de Wucherer;” ibid., 15 de Setemb., 1878, p. 589.—Makina, M.D., “Filaria in Chyluria,” letter in ‘Lancet,’ Feb. 22, 1879, p. 286.—Manson, P., “Rep. on Hæmatozoa,” ‘Customs Gazette,’ No. 33, Jan.–March, 1877; see also ‘Med. Times and Gaz.’ for Nov. 10, p. 513, Nov. 17, p. 538, and Nov. 24, p. 563; Dec. 1, p. 589, 1877; also Jan., 1878.—Idem, “Additional Cases;” ibid., March 2, 9, 23, 1878.—Idem, “On Filaria sanguinis hominis, and on the Mosquito considered as a Nurse,” ‘Proc. Linn. Soc.,’ March 7, 1878; see also report in ‘Nature,’ March 28, 1878, p. 439.—Idem, “On Filaria sanguinis hominis, clinically considered in reference to Elephantiasis, Chyluria, and allied Diseases,” ‘Rep. of Med. Soc. of Lond.,’ in ‘Lancet,’ March 30, 1878.—Idem, “Further Observations on Filaria sanguinis hominis,” “Med. Rep.” for April–Sept., 1877, in ‘Customs Gazette,’ Shanghae, 1878.—Idem, “The Development of the Filaria sanguinis hominis,” ‘Med. Times and Gaz.’ for Dec. 28, 1878, p. 731.—Méricourt, A. Le Roy de, in Appendix to an art. entitled “Nouvelle phase de la question relative à la nature parasitaire de la chylurie. Découverte du représentant adulte de la ‘Filaire de Wucherer,’” par le Dr da Silva Lima, from the ‘Gaz. Med. da Bahia,’ Sept., 1877; see also the ‘Lancet,’ Jan., 1878, p. 22 (editorial notice).—Moura, J. de, ‘These de Concourso,’ 1877.—O’Neill, “On Craw-craw,” ‘Lancet,’ Feb., 1875.—Pareira, A. P., “On Bilharzia and Chyluria,” ‘Gazeta Med. da Bahia,’ No. 9, 1877 (noticed in ‘Lancet,’ Feb. 2, 1878).—Salisbury, J. H., “On the Parasitic forms developed in Parent Epithelial Cells of the Urinary and Genital Organs,” ‘Hay’s American Journ.,’ vol. iv, 1868, p. 376.—Santos, F. dos, in ‘Gaz. Med. da Bahia,’ March, 1877.—Sonsino, P., ‘Richerche,’ &c., 1874; ‘Della Bilharzia,’ &c., 1876; ‘Sugla Ematozoi,’ &c., 1876 (see Bibl. No. [12]).—Idem, “On the Diagnosis of Embryos of Filaria,” in his paper ‘Sull’ Anchylostoma duodenale;’ ‘Estr. dall Imparziale,’ 1878.—Sousa, M. de A., ‘Memoria sobre a Elephantiasis do escroto,’ Bahia, 1878.—Wucherer, O., “Noticia Preliminar,” &c., ‘Gaz. Med. da Bahia,’ Dec., 1868.—Idem, ‘Sobre Hematuria no Brazil,’ ibid., Sept., 1869; see also “Méricourt’s trans. (De l’hématurie intertropicale observée au Brézil),” ‘Arch. de Méd. Nav.,’ p. 141, 1870, and the fuller references quoted in my memoir; ‘Linn. Soc. Journ., Zool.,’ vol. xiv, p. 368.
Filaria Loa, Guyot.—Although further examinations of this worm will probably result in placing it in some other genus than Filaria, yet it is by no means clear that Diesing was right in placing it with the genus Dracunculus. I therefore abandon the nomenclature adopted in my previous treatise. According to the surgeon, Guyot, who made seven separate voyages to the coast of Angola, these worms cannot be confounded with the Dracunculus. They are quite white, and relatively much thicker than guinea-worms. Under the title of Filaria oculi Moquin-Tandon has spoken of certain small nematodes as “not uncommon in the negroes of the Angola coast;” and he gives other localities where it occurs. The worms are identical with those described by Guyot as dwelling beneath the conjunctivæ of negroes at Congo and in the Gaboon region generally. The parasite is rather more than an inch and a quarter in length, being pointed at one end and blunt at the other. It is termed Loa by the natives, who state that after a period of several years the worm voluntarily quits the organ. The disease is thus naturally cured. This parasite enjoys a tolerably wide geographical distribution, as it has been observed by Clot Bey in a negress who had come from the town of Monpox, situated on the banks of the River Magdalena; by Sigaud, who saw one in the eye of a negress in Brazil; by Blot, at Martinique, who saw two in a negress originally from Guinea; by Bajon, who met with one in a little negro girl who had come from Guadeloupe; by Mongin, who found one in a negress who had been living in the Island of San Domingo; and by Lestrille, who removed one from beneath the conjunctiva of a negro who came from Gaboon.
Bibliography (No. 24). Davaine, l. c., p. 839.—Guyon, ‘Gaz. Méd. de Paris,’ p. 106, 1841, and in ‘Micr. Journ. and Struct. Record,’ p. 40, 1842, and in ‘Dublin Journ.,’ vol. xxv, p. 455, 1839.—Idem, ‘Compt. Rendus,’ tom. lix, p. 743, 1865.—Guyot, in ‘Mém. par Arrachait,’ p. 228, 1805.—Küchenmeister, l. c., s. 322.—Lestrille, in Gervais and Van Beneden’s ‘Zool. Med.,’ 1859, also quoted by Davaine, l. c., 2nd edit., p. 840.—Leuckart, l. c., s. 619.—Moquin-Tandon, A., ‘Zool. Med.,’ Hulme’s edit., p. 363, 1861.
Filaria lentis, Diesing.—This is a doubtful species. The worm was first discovered by Nordmann, in a case of lenticular cataract under the care of Von Gräfe, and it was afterwards found by Jüngken in a similar case, as recorded by Sichel. There is also the instance described by Gescheidt, in which Von Ammon operated, and from which brief descriptions of the worm have generally been taken. In this case there were three worms, two measuring about 1/6″ and the third 1/15″ in length. In Jüngken’s case (exhibited by Quadri, of Naples, at Brussels) the worm was more than 3/4″ long. In another case, reported by M. Fano, the worm was somewhat less than 1/4″ long. There is no certain evidence that any of these various worms had developed sexual organs in their interior. It is true that the reproductive organs were described in two of the worms observed by Gescheidt; but after a due consideration of all the facts I fear we must conclude that all the worms in question were sexually-immature and wandering nematodes, possibly referable to Gurlt’s Filaria lacrymalis, as Küchenmeister long ago suggested.
Bibliography (No. 25).—Cobbold, ‘Entozoa,’ p. 332.—Davaine, l. c., p. 821 et seq.—Diesing, ‘Syst. Helm.,’ p. 625.—Fano, ‘Traité des Malad. des Yeux,’ tom. ii, p. 498; and in ‘Rec. de Méd. Vét.,’ p. 140, 1869; quoted by Davaine, p. 831.—Gescheidt, Ammon’s ‘Zeitsch.,’ 1833, s. 435.—Leuckart, l. c., Bd. ii, s. 622.—Nordmann, l. c., Bibl. No. 2, s. 7, 1832.—Sichel, ‘Iconogr. Ophth.,’ p. 707, 1859.