SUB-ORDER HETEROMASTIGINA Family: Trypanosomatidae, Doflein. Flagellates, in the great majority of instances haemal parasites, derived from a biflagellate, Bodo-Vke. type, in which the posteriorly-directed (trailing) flagellum is always present and attached to the body by an undulating membrane, of which it constitutes the thickened edge. The other, the anterior flagellum, may or may not persist.
Genus Trypanoplasma, Lav. and Mesnil, 1902. The anterior flagellum is present. Both flagella are inserted close together, near the anterior end of the body. Two sub-groups may be distinguished. In one, exemplified by T. borreli (fig. 4, F and G) from the rudd and minnow, the anterior flagellum is well-developed, and the free parts of both are of about equal length. In the other, exemplified by T. cyprini (fig. 4, H) from carp, the anterior flagellum is much shorter than the free part of the posterior one, and evidently tending to disappear. Known invertebrate hosts for different species are Hemiclepsis and Piscicola, leeches.
Genus Trypanophis, Keysselitz, 1904. The body resembles that of Trypanoplasma in general appearance, but the locpmotor apparatusdoes not appear to be so well-developed, especially in T. grobbeni. The anterior flagellum is longer than the free part of the posterior one. The species included are not, so far as is known, haemal parasites. T. grobbeni occurs in the coelenteric cavity of various Siphonophora.
An interesting form, " Trypanoplasma " intestinalis, which resembles both the above genera, occurs in the alimentary canal of Box hoops. Probably this is not a haemal parasite, and lacks an alternate host.
Genus Trypanosoma, Gruby, 1843. (Principal synonyms: Undulina. Lank., 1871; Herpetomonas, Kent, 1880, only in part; Paramoecioides, Grassi, 1881; Haematomonas, Mitrpphan, 1883.) There is no anterior flagellum. The point of insertion of the attached (posterior) flagellum into the body, and, consequently, the commencement of the undulating membrane may be almost anywhere in the anterior half of the body, but is usually near the extremity.
Among the more important and better-known forms are the following :
Parasitic in mammals: T. lewisi (Kent), the well-known natural Trypanosome of rats (figs. 3, A, 6, A) ; T. brucii, Plim. and Bradf., the cause of nagana among cattle, horses, etc., in South Africa (fig. 3, B) ; T. evansi, Steel, the cause of surra to horses in IndpBurmah; T. equiperdum, Dofl., the cause of dpurine in horses in Algeria and other regions of the Mediterranean littoral ; T. equinum, Voges, causing mal de caderas or " hip-paraplegia " in South America (fig. 3, D) ; T. theileri, Lav., a very large form, the cause of falziektfi or bile-sickness to cattle in the Transvaal; and T. gamtense, Dutton (syn. T, ugandense, Castellani, T. castellanii, Kruse), the cause of human trypanosomosis in central Africa, which becomes sleeping-sickness when the organisms penetrate into the cerebro-spinal fluid (fig. 3, C).
Parasitic in birds: T. avium (Danil., Lav. emend.), probably the form to which Danilewsky's original investigations related, parasitic in owls and (according to Novy and McNeal) also in other birds (fig. 3, F) ; T. johnstoni, Dutt. and Todd, a very spirochaetiform type, from little birds (Estrelda) in Senegambia; and Hanna's peculiar wide species from Indian birds, with a remarkably tapering anterior end (fig. 3, G). Lastly, there is T. ziemanni, Lav., [syn. Spirochaete z. (Lav.), Schaud, " Haemamoeba " z., Lav., the " Leucocytozpon " of Danil.], from various owls, and Culex pipiens, whose life-history has been described by Schaudinn (fig. 3, H). (As above mentioned, this form may not be a true Trypanosome.)
Only one reptilian form is well known, T. damoniae, Lav. and Mesn., from a tortoise, Damonia reevesii (fig. 3, J). Parasitic in batrachia: T. rotalorium, Mayer (syn. Amoeba r., Mayer, July 1843, T. sanguinis, Gruby, November 1843, Undulina ranarum, Lank., 1871), the best-known parasite of frogs, which exhibits remarkable polymorphism (fig. 4, A and B) ; T. mesa and T. karyozeukton, Dutt. and Tpdd, even larger than T. r. (fig. 4, D), with peculiar cytological differentiation, may be only sub-species; T. inopinatum, Sergent, and T. nelspruitense, Lav., also from frogs (fig. 4, C). Parasitic in fishes: T. remaki, Lav. and Mesnil, from pike, a relatively small form (fig. 4, L); T. barbatulae, L6ger, from loach; T. granulosum, Lav. and Mesnil, a very long vermiform parasite, from eels (fig. 4, K) ; T. soleae, Lav. and Mesnil, from soles, with a relatively small flagellum (fig. 4, J); and T. scyllii and T. rajae, from those Elasmobranchs, both very large forms, described by Lav. and Mesnil.
Undoubtedly closely allied to the Haemoflagellates, although no actual trypaniform phase has yet been observed, are the important parasites usually known as the " Leish- Thg man-Donovan " bodies, without some consideration Leishmtaof which an account of the Haemoflagellates would Doaovaahardly be complete. These bodies are constantly found in certain tropical fevers (e.g. dum-dum fever, kala-azar) particularly prevalent throughout Indo-Burma, of which they are generally held to be the cause. They were discovered by W. Leishman in 1900, but before his first account of them (36) was published they were also seen quite independently by C. Donovan. Moreover, organisms very similar to these (morphologically, indeed, the two sorts appear scarcely distinguishable) are found in various sores or ulcers (e.g. Delhi boil, Oriental sore, " bouton d'Alep ") to which people in different parts of the East are liable. These were first described by J. H. Wright (58).
The chief distinction between the parasites in the two cases is in their habitat. In the one case they are entirely restricted to the neighbourhood of the boil or ulcer, whereas in the other there is a general infection of the body, the organisms spreading to all parts and being met with in the spleen, liver, bone-marrow, etc., and (rarely) in the peripheral circulation. The parasites are either free or intracellular. In the latter case they invade cells of a leucocytic or phagocytic character as a rule; Leishman's form is particularly abundant in large macrophageal cells originating from the vascular endothelium of the spleen (fig. 8, I. M).
The parasites themselves are very minute and usually ovoid or pyriform in shape (fig. 8, I. a), the latter being, perhaps, the most typical. The splenic type is somewhat smaller than Wright's parasite; the former, when pear-shaped, is from 33 to 4 M in length by ij to 2 fi in width, the latter being about 4 n by 3 ft (fig. 8, III.). The body is probably not limited by any distinct membrane. The cytoplasm is finely granular and fairly uniform in character. The most interesting point about the morphology is the fact that two chromatic bodies, of very unequal size, are almost invariably to be recognized. The larger nuclear body, which corresponds to the trophonucleus of a Trypanospme, is usually round or oval; the smaller one, representing a kinetonucleus, has the form either of a little rod or of a round grain, and is generally separate from the larger nucleus.
The parasites multiply in two ways (a) by binary fission, and (b) by multiple division or segmentation. The principal stages in the first method are well known (fig. 8, I. 6); they offer strong resemblance to the process in Piroplasma. Multiple division has not yet been so satisfactorily made out. It appears to conform more or less to the radial or rosette type of multiplication, enlarged rounded parasites, with a varying number of nuclei (up to about eight) uniformly arranged near the periphery, having been often noticed (fig. 8, I. c and IV. b). The details of the process are somewhat differently described, however, by different observers.
Laveran and Mesnil (27) gave the name Piroplasma donovani to Irishman's form, 1 and there is no doubt that the parasites are closely allied to that type of organism. This does not, however, preclude in any way the supposition that they equally with certain other Haemosporidia represent, nevertheless, only a phase of a complete life-cycle; and this supposition has in fact been definitely proved to be true by the work of Rogers (48). Rogers cultivated the parasites obtained from cases of kala-azar in artificial media, and found that what were unmistakably flagellate FIG. 8.
I. Piroplasma (Leishmania) donovani, Lav. and Mesnil.
a, Typical pear-shaped or oval forms; b, various stages in longitudinal division; c, nuclear division preparatory to multiple fission; d, endoglobular forms, in red blood-corpuscles (P = pigment grains) ; e, bacillary form of the parasite in a corpuscle; M, large macrophageal cell with many parasites (after Donovan).
II. Uninuclear leucocyte (L) containing several parasites (after Lav.
III. P. (Heleosoma) tropicum (Wright).
a, Single individuals; 6, dividing forms (from Mesnil, mostly after Wright).
IV. P. donovani in cultures of different ages.
a, Ordinary forms of varying sizes; b c, stages in multiple division; d, binary fission; e, /, g, flagellate forms (after Rogers), stages developed in the cultures at different intervals (fig. 8, IV. e, j, g). These forms were elongated and spindle-like; and to one end of the body, near which the smaller nuclear element was situated, a well-developed flagellum was attached. Since then many other workers have obtained similar stages [see Leishman and Statham (38), Christophers (7)]; but however slender and Trypanosomelike the flagelliform parasites may appear, up till now no indications of an undulating membrane have been seen, and the kinetonuclear element is never far from the insertion of the flagellum.
Nevertheless, the general appearance and structure of these motile forms so greatly resemble that of a Herpetomonad, or of the " pseudo-Herpetomonadine " forms of a Trypanosome which are obtained in cultures, that it cannot be doubted that the " Leishman-Donovan-Wright " bodies are closely connected with the Haemoflagellates. That being so, it is quite possible that, in normal conditions and circumstances, these parasites also possess, at some period of the life-cycle, a trypaniform phase. Nothing definite is yet known with regard to the transmission of the parasites by an alternate invertebrate host, although there is presumptive evidence in favour of this supposition. 2 A word or two must be said in conclusion with reference to . the supposed connexion of the Spirochaetae with the Supposed ... .
Connexion Trypanosomes. In Schaudinn s great memoir he oftheSpiro- regarded Trypanosoma ziemanni as possessing, in chaetae with certain phases, the actual characteristics of a paoo- Spirochaete as then known; and, further, he was inclined to think that other Spirochaetae (e.g. S.
obermeieri of relapsing fever) were also only phases in the 1 R. Ross (49), regarding the parasites as a quite different kind of Sporozoan, termed them Leishmania; and Wright named his variety from tropical ulcers Heleosoma tropicum.
2 Patton (Sci. Mem. India, No. 27, 1907) has brought forward evidence to show that the bed-bug (Cimex macrocephalus) is the invertebrate host.
life-cycle of a particular Haemoflagellate. As a result of his more recent investigations on S. plicalilis (the type-species of Ehrenberg) and other forms (51), he finds, however, that this is not the case, but that the organisms exemplified by S. plicatilis are to be widely separated from the Trypanosomes, and placed rather with the Bacteria. In addition, it is most probable that, at any rate, certain other spirilliform parasites, e.g. S. balbianii, S. refringens, agree fundamentally in structure with the type-species. .
On the other hand, evidence has lately been brought forward to show that certain parasites which greatly resemble a Spirochaete are really related to the Trypanosomes. This is the case with the celebrated organism first described by Schaudinn and E. Hoffmann (52) from essential syphilitic lesions, and now known as Treponema (Spirochaete) pallida, Schaud. F. Krzysztalowicz and M. Siedlecki have published an important account (17) of this parasite, which they consider possesses a true trypaniform phase, and for which they have proposed the name Trypanosoma luis. This view requires, however, corroboration. Nevertheless the resemblance between the biology of this organism in relation to syphilis (as regards mode of infection, habitat, etc.) and that of Trypanosoma equiperdum, the cause of dourine or " horse-syphilis," may not be without significance.
BIBLIOGRAPHY. A comprehensive review of the Haemoflagellates and allied parasites, considered up to the end of 1905, has been published by (i) H. M. Woodcock, Quart. Journ. Mic. Sci. (1906), 50, p. 150. The principal original papers referred to are: (10) A. Billet, " Culture d'un trypanosome de la grenouille chez une hirudinee," etc., C. r. ac. sci. (1904), 139, p. 574; (2) " Sur le Trypanosoma inopinatum de la grenouille verte d'Algerie et sa relation possible avec les Drepanidium," C. r. soc. mot. (1904), 57, p. 161, figs; (3) J. R. Bradford and H. G. Plimmer, "The Trypanosoma brucei, the organism found in Nagana or the Tsetsefly disease," Quart. Journ. Mic. Sci. (1902), 45, p. 449, with pis.; (4) D. Bruce, D. Nabarro and E. D. Greig (various reports on sleeping-sickness and other trypanosomoses in Uganda), Roy. Soc. Comm. (1903-1905), Nos. I, 4 and 5; (5) E. Brumpt, " Contribution & 1'etude de 1'evolution des hemogregarines et des trypanosomes," C. r. soc. biol. (1904), 57, p. 165; (50) idem," On the mode of transmission and development of Trypanosomes and Trypanoplasms in leeches," C. r. soc. biol. (1906), 60, pp. 160, 162; and op. cit. (1906), 61, p. 77; (6) A. Castcllam, " Trypanosoma and Sleepingsickness," Rep. Sleeping-sickness Comm. Roy. Soc. (1903), Nos. I and 2; (7) S.R.Christophers, "Reports on a parasite found in persons suffering from enlargement of the spleen in India," Sci. Mem. India (1904- 1905), Nos. 8, II and 15; (8) Danilewsky, " Recherches sur la parasitologie comparee du sang des oiseaux (Kharkoff, 1888-1889); (9) D. Doflein, Die Protozoen als Parasiten Una Krankheitserreger, (Jena [G. Fischer], 1901); (10) C. Donovan, "Human Piroplasmosis," Lancet (1904), p. 744, I pi.; (n) E. Dutton, "Note on a Trypanosoma occurring in the Blood of Man," Brit. Med. Journ. (1902), p. 881; (12) Dutton and J. L. Todd, " First Report of the Trypanosomiasis Expedition to Senegambia, 1902," Mem. Livpl. Sch. Trap. Med. (1903) n; (13) Gruby, "Recherches et observations sur une nouvelje espece d'Hematozoaire ( Trypanosoma sanguinis) " C. r. ac. sci. (1843), 17, p. H34. also Ann. sci. nat. (1844), 3, i. p. 105, figs.; (14) W. Hanna, "Trypanosoma in Birds in India," Quart. Journ. Mic. Sci. (1903), 47, p. 433, i pi.; (15) G. Keysselitz, " Vber Trypanophis grobbem (Trypanosoma grobbeni, Poche)," Arch. Protistenk. (1904), 3, p. 367, figs.; (16) idem, " Generations- und Wirthswechsel von trypanoplasma borreli, Lav. u. Mesnil," op. cit. 7, p. I, figs. ; (160) R. Koch, " Mittheilungen iiber den Verlauf der deutschen Expedition ... in Ostafrika," Deutsch. med. Wochensch. (1906), app., p. 51; op. cit. (1907), p. 49; (17) F. Krzysztalowicz and M. Siedlecki, " Contribution a 1'etude de la structure et du cycle evolutif de Spirochaete pallida, Schaud.," Bull. Ac. Cracovie (i95). p. 713, i pi.; (18) E. R. Lankester, "On Undulina, the type of a new group of Infusoria," Quart. Journ. Mic. Sci. (1871), 1 1, p. 387, figs. ; (19) " The Sleeping-sickness," Quart. Rev. (July 1904), p. 113, figs.; (20) A. Laveran, "Sur un nouveau trypanosome des bovides," C. r. ac. sci. (1902), 134, p. 512; (21) idem, " Sur un trypanosome d'une chouette," C. r. soc. biol. (!9 O 3). 55. P- 528, figs.; (22) idem, " Sur un nouveau trypanosome d'une grenouille," op. cit. (1904), 57, p. 158, figs.; (23) Laveran and F. Mesnil, " Recherches morphologiques et experimentales sur le trypanosome des rats, Tr. lewisi (Kent)," Ann. tnst. Pasteur (1901), 15, p. 673, 2 pis. ; (24) idem, "Des Trypanosomes des poissons," Arch. Protistenk. (1902), i, p. 475, figs.; (25) idem, " Recherches morphologiques et experimentales sur le trypanosome du Nagana ou maladie de la mouche tse-tse," Ann. inst. Past. (1902), 16, p. i, figs.; (26) idem, Trypanosomes et trypanosomiases (Paris [Masson et Cie], 1904); (27) idem, " Sur un protozoaire nouveau (Piroplasma donovani. Lav. et Mesn.) parasite d'une fieVre de 1'Inde, " C. r. ca. sci. (1903), 137, p. 957, figs,; (28) idem, " Sur la nature bacteYienne du pritendu trypanosome des huitres, T. balbianii, " C. r. soc. biol. (1901), 53, p. 883; (there are numerous other papers by these authors in the C. r. ac. sci. and the C. r. soc. biol. from 1900 onwards); (29) L. Leger, "Sur un flage!16 parasite de I' Anopheles maculipennis," C. r._ soc. biol. (1902), 54, p. 354, figs. ^(30) idem, " Sur la morphologic du trypanoplasma des vairons," C. r. ac. sci. (1904), 138, p. 824; (31) idem, " Sur la structure et les affinites des trypanoplasmes " (1904), t. c. p. 856, figs.; (32) idem, " Sur les (1904), t. c. p. 345; (34) idem, " Sur les affinity's de VHerpetomonas subulata et la phylogcnie des trypanosomes " (1904), t. c. p. 615; (35) idem, " Sur la presence d'un trypanoplasma intestinal chez les poissons," op. cit. (1905), 58, p. 511; (36) W. Leishman, "On the possibility of the occurrence of trypanosomiasis in India," Brit. Med. Journ. (1903), i. 1252, figs.; (37) idam, " Note on the nature of the parasitic bodies found in tropical splenomegaly," op. cit. (1904), i. 303 ; (38) Leishman and Statham, " The development of the Leishman body in cultivation," Journ. Army Med. Corps (1905), 3, 14 pp., I pi. ; (39) J. Lignieres, " Contribution 4 1'etude de la trypanosomose des equidiSs sud-americains' connue sous le nom de Mai de Caderas," Rec. med. vet. (8) (1903), 10, p. 51, 2 pis. ; (40) A.F.Mayer, " Spicilegium pbservationum anatomicarum de organo electrico in raiis anelectrias et de haematozois," (Bonn, 1873), 18, pp., pis.; (41) F. Mesnil, F. Nicolle and P. Remlinger, " Sur le protozoaire du bouton d'Alep," C. r. soc. biol. (1904), 57, p. 167; (410) E. A. Minchin, " On the occurrence of encystation in Trypanosoma grayi," etc., Proc. Roy. Soc. (1907), 79 B,p. 35.; (416) idem (with Gray and Tulloch), " Glossina palpalis in relation to Trypanosoma gambiense," etc., op. cit. (1906), 78 B, p. 242, 3 pis.; (42) Mitrophanow, " Beitrage zur Kenntniss der Hamatozen," Biol. Centbl. (1883), 3. p. 35, figs.; (43) G. Nepveu, " Sur un trypanosome dans le sang de 1'homme," C. r. soc. tool. (1898), 50, p. 1172; (44) F. G. Novy and W. I. McNeal, " On the Trypanosomes of Birds," Journ. Inf. Dis. (1905), 2, p. 256, pis.; (45) W. S. Perrin, " The life-history of Trypanosoma balbianii" Proc. Roy. Soc. (1905), 76 B, p. 367, figs., also in Arch. Protistenk. (1906), 7 pis.; (46) M. Plehn, " Trypanoplasma cyprini, n. sp.," Arch. Protistenk. (1903), 2, p. 175, I pi.; (47) S. Prowazek, " Studien tiber Saugethiertrypanosomen," Arb. kais. Gesundheitsamte (1905), 22, 44 pp., pis.; (48) L. Rogers," On the development of flagellated organisms (Trypanosomes) from the spleen Protozoic parasites of cachexial fevers and Kala-azar," Quart. Journ. Mic. Sci. (1904), 48, p. 367, i pi.; 149) R. Ross, " Notes on the bodies recently described by Leishman and Donovan, " Brit. Med. Journ. (1903), i. 1261, 1401, figs. ; (50) F. Schaudinn, " Generations- und Wirthswechsel bei Trypanosoma und Spirochaete," Arb. kais. Gesundheitsamte (1904), 20, p. 387, figs.; (51) idem, " Zur Kenntniss der Spirochaete pallida," Deutsch. med. Wochenschr. (1905), No. 42, p. 1665; (52) Schaudinn and E. Hoffmann, " Vorlaufiger Bericht iiber das Vorkommen von Spirochaeten in syphilitischen Krankheitsproducten , " Arb. kais. Gesundheitsamte (1905), 22, p. 527; (53) E. and E. Sergent, " Sur un trypanosome nouveau parasite de la grenouille verte," C. r. soc. biol. (1904), 56, p. 123, fig. ; (54) idem, " Hemamibes des oiseaux et moustiques ' Generations alternantes,' de Schaudinn," op. cit. ( I 95) 5 8 > P- 57; (54o) F. Stuhlmann, " Beitrage zur Kenntniss derTsetsefliege,"etc., Arb. kais. Gesundheitsamte (1907), 26, p. 83, 4 P.' 8 '. (55) Valentin, " (Jber ein Entozoon im Blute von Salmo fario, " Mutter's Arch., $\, -p. 435; (56) O. Voges, " Mai de Caderas," Zeitschr. Hyg. (1902), 39, p. 323, I pi.; (57) Wasielewsky and G.Senn, " Beitrage zur Kenntniss der Flagtllaten des Rattenblutes," op. cit. (1900), 33, p. 444, pis. (58); J. H. Wright, "Protozoa in a case of tropical ulcer (Delhi sore), " Journ. Med. Research, Boston (1903), 10, p. 472, pis. (H. M. Wo.)
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)