Trypanosoma

“ Apparently the Trypanosoma can live in the blood without doing much harm, and only when it reaches the cerebro-spinal canal does it set up the sleeping-sickness. It is also found in great numbers in the lymphatic glands, especially those of the neck, which in patients infected by the parasite are usually swollen and tender. From the similarity of the parasite to that causing the cattle disease of South Africa, the idea at once arose that the Trypanosoma was conveyed from man to man by a biting insect. ”

“ South American Trypanosomiasis—The tsetse-flies are distinctively African in distribution and until recently there were no trypanosomes known to infest man in America. In 1909 Dr. Chagas, of Rio de Janeiro described a new species, Trypanosoma cruzi, pathogenic to man.
Trypanosoma cruzi is the causative organism of a disease common in some regions of Brazil, where it is known as "opilacao." It is especially to be met with in children and is characterized by extreme anemia, wasting, and stunted development associated with fever, and enlargement of the thyroid glands. ”

“ History.—— Although its true etiology was not apprehended until quite recently, sleeping sickness, the terminal phase of African trypanosomiasis, has been known for over a century.
The occurrence of trypanosomes in animals has been recognized for at least sixty years, first in cold-blooded vertebrates, later in mammals. The best-known and first-described mammalian species is that of the rat (Trypanosoma lewisi) . It was discovered by Lewis, in 1879, in Calcutta. In the following year Evans described a similar parasite (T.evansi) in the blood of horses in India ”

“ Trypanosomes vary greatly with regard to size; even in one and the same species this variation is often noticeable, especially under Mon, , w, oD, different conditions of life. The common Trypanosoma rotatorium of frogs (fig., A and B) is, taking it all in all, one of the largest forms so far described. Its length (inclusive of the flagellum) varies from 40-60 p, while its greatest width (including the undulating-membrane) is from 8-30, a; in the very wide individuals breadth is gained more or less at the expense of length. ”

“ They live in the blood-plasma and do not attack the corpuscles. In some animals they are apparently harmless; in others they are an important cause of disease.
Trypanosoma hominis is an actively motile, spindle-shaped organism, two or three times the diameter of a red corpuscle in length, with one end terminating in a long flagellum. It can be seen with medium power objectives in either fresh or stained blood. Human trypanosomiasis is common in Africa. As a rule, it is a very chronic disease. "Sleeping sickness" is a late stage when the organisms have invaded the cerebrospinal fluid. ”

“ Death may occur early with general anasarca and extreme hyperthermia (110° F.) . In the great majority it appears to result largely from perforation of the stomach, clots in the heart, or general debility and heart failure.
Diagnosis. With symptoms such as are above described the discovery of the trypanosoma in the blood completes the diagnosis. Trypanosoma is found in dourine, nagana and other affections so that the discovery of it alone would not be conclusive as to the existence of surra. Nor can the discovery of the parasite always be made at the first or second attempt. ”

“ Glossina palpalis is the chief carrier of the more prevalent type of sleeping sickness. Two distinct types of parasites can produce this disease, viz., Trypanosoma gambiense, which produces the ordinary sleeping sickness, transmitted by G. palpalis, and Trypanosoma rhodesiense the Rhodesian or Nyasaland sleeping sickness, transmitted by G. morsitans, and possibly identical with T. brucei, the parasite of N’agana. Koch has also shown that G. pallidipes, Austen, and G. fusca, Walker, can be artificially infected with the human trypanosome. ”

“ Fortunately for the elucidation of problems relating to the methods of transfer of sleeping sickness, Trypanosoma gambiense is pathogenic for many species of animals. In monkeys it produces symptoms very similar to those caused in man. Bruce early showed that Glossina palpalis "fed on healthy monkeys eight, twelve, twenty-four and forty-eight hours after having fed on a native suffering from trypanosomiasis, invariably transmitted the disease. After three days the flies failed to transmit it." ”

“ The discovery of the parasite and its relation to the fly and the disease was as beautiful a piece of scientific investigation as biologists have ever seen. A curious and very important fact was discovered by Bruce—namely, that the native big game (zebras, antelopes, and probably buffaloes) , are tolerant of the parasite. The Trypanosoma grows and multiplies in their blood, but does not kill them or even injure them. It is only the unaccustomed introduced animals from Europe which are poisoned by the chemical excreta of the Trypanosomes and die in consequence. ”

“ These parasites were first seen by Gruby, who named them in 1843, in the blood of a frog; they live, not as does the malaria parasite, in the blood-cells, but in the fluid of the blood. The particular species of Trypanosoma which causes nagana is Trypanosoma brucei, and it does not attack man, and some goats and donkeys seem also immune; but, with these exceptions, all domesticated animals suffer, and in a great percentage of cases the disease terminates in death. ”

“ During this expedition he identified in the blood of a patient at Bathurst a trypanosome belonging to a group of animal parasites which had hitherto been found only in animals. He described it accurately and named it Trypanosoma Gambiense. He found the same organism subsequently in numerous other cases in Gambia and elsewhere. Dutton's discovery of the first trypanosome in man was an important factor in determining the cause of sleeping sickness, which was afterwards shown by other observers to be due to the same parasite. ”

“ The Trypanosomes, in the active phase, are of course always free in the blood plasma (interglobular) . In the majority of cases it is very uncertain whether they actually come into relation with the blood corpuscles or not. Schaudinn has stated, however, that Trypanomorpha becomes, in certain phases, attached to a red blood-corpuscle (ectoglobular) , and, in others, penetrates inside one and eventually destroys it (endog1obular) ; while his other avian parasite, Trypanosoma ziemanni, apparently draws up into itself the white corpuscle (leukocyte) to which it becomes attached. ”

“ NAGANA. TSETSE FLY DISEASE. Trypanosoma Brucii: attacks horse, ass, mule, cattle, buffalo, antelope, camel, hyena, dogs, etc. Elephants and zebra, pigeon and hen immune. Tsétsé fly. Inoculation only certain channel; virulence in dead body 24 hours; in vitro 3 to 4 days, or when dried or heated (122° F.) Symptoms: hyperthermia; anæmia; leucocytosis; buffy coat; œdemas; catarrhs; wasting; debility. Lesions: as in surra; trypanosoma in blood at intervals, bone marrow, lymph glands, spleen. Immunizing unsuccessful. Prevention as in surra. ”

“ The peculiar form of the protozoa, however, can only be detected in stained preparations. Romanowsky’s staining method is 427probably the best. Trypanosomata stained by this method show a fish-shaped body, the front end of which carries a flagellum. The body of the trypanosoma is coloured blue. At the anterior end may be seen a red-stained nucleus; at the opposite end a much smaller red spot, which has been termed the nucleolus, but is more properly described as the centrosome. ”

“ Agglomeration consists in the grouping or union together of several Trypanosomes around a common centre; this leads to the formation of rosette-like clusters, or even of large masses composed of several rosettes. The end by which the parasites join is typically, in the case of Trypanosoma, the non-flagellate (anterior) end. If a favourable change in the surrounding medium sets in, the Trypanosomes are able to undergo the reverse process, namely dis agglomeration; the parasites liberate themselves and the rosette is dissolved. ”

“ In man they may be either comparatively harmless flagellates, swimming about in the blood plasm, or, by bursting of the capillaries, they may penetrate the membranes of the brain and spinal cord and give rise to the invariably fatal disease of man—'sleeping sickness.' The presence of Trypanosoma gambiense in the human blood gives rise to the 'trypanosome fever' of Africa, not much worse apparently than is malaria in this country, but when the parasites enter the nervous system and congregate in the cerebro-spinal fluid, or in the ventricles of the brain, the result is invariably fatal. ”

“ According to Low and Castellani, the average duration of this stage of trypanosomiasis in the African is from four to eight months, not infrequently less; very chronic cases with a course of more than a year's duration are rare. Other observers refer to cases running on for three years, or even longer, and presenting occasionally temporary ameliorations.
Generally the first indications of the oncoming of sleeping sickness are merely an accentuation of the debility and languor usually associated with trypanosoma infection. There is a disinclination to exertion ”

“ So closely allied to this group in form, habit, and life-cycle are some species of the Flagellate genus Trypanosoma, that in their less active states they have been unhesitatingly placed here (see p. 119) . Schaudinn has seen Trypanosomic characters in the "blasts" of this group, which apparently is the most primitive of the Sporozoa and a direct offshoot of the Flagellates.
The Myxosporidiaceae (Fig. 36) are parasitic in various {107}cold-blooded animals. ”

“ It is now, largely owing to the researches of Colonel Bruce, known to be due to the{168} inoculation of the beasts with a minute parasitic organism conveyed from host to host by the fly. The disease is known as ‘nagana,’ and the organism that causes it is a species of Trypanosoma, a flagellate Protozoon or unicellular organism, which moves by means of the lashing of a minute, whip-like process. Since Bruce’s researches a number of Trypanosomas have been found causing diseases in various parts of the world. Thus T. evansii causes the ‘surra’ disease of cattle, horses, and camels in India. ”

“ Acute protozoan remittent fever, of rainy season or after, with destruction of red globules, anæmia, emaciation, dropsy, icterus and cutaneous or mucous eruption or discharge. Distribution: India, Burma, Cochin China, Persia, Phillipines, etc. Trypanosoma Evansi: a fusiform flagellate infusorian with undulating membrane, attacking the red globules: agency of flies as carriers, infection of dogs; of crows; feeding, licking; rats; open sores; stables; yards; pastures; pickets; stagnant water; manure or rubbish heaps; abattoirs. Lesions: anæmia; trypanosoma swarms during relapses; leucocytosis ”

“ C) ; in Trypanomorpha it is in the posterior half of the body (fig. 3, E) . In certain forms the occurrence of prominent myonemes or muscle-fibrillate has been described, and, moreover, a nuclear origin assigned to them also. In Trypanomorpha they are confined to the undulating-membrane (fig. 3, E) , but in other cases—Trypanosoma ziemanni, T. lewisi, T. brucei, and T. soleae-they are arranged laterally, half running down each side of the body (fig. 4, J) . In Trypanoplasma borreli there is only a single myoneme on either side. ”

“ Darling108 (November, 1914) has seen the organism in Panama. He describes free crithidial forms in shed blood, but not in the blood-stream of the sloth.
Trypanosoma boylei, Lafont, 1912.
This is a parasite of the Reduviid bug, Conorhinus rubrofasciatus. The insect attacks man in Mauritius, Réunion and other places. Lafont infected rats and mice by intraperitoneal injection with the gut-contents of infected bugs. Trypanosomes appeared in the mice. Other flagellate types were assumed by the parasites in the bug. ”

“ Many features of the disease reminds one of surra—for example its relation to hot weather, its relation to buildings and enclosures with their accumulations of decomposing organic matter and swarms of flies, the decomposition of the blood, anæmia, icterus of the white tissues, petechiæ, extreme weakness, muscular atrophy, and marasmus. Calendrini’s cures followed by relapses suggest the further coincidence of intermissions. If now the trypanosoma were discovered in the blood it might be recognized as at least a near ally of surra.
Mortality. Prognosis. The disease is nearly always fatal. ”

“ This rat trypanosome is transmitted by fleas and lice.
Old, J.E.S. Contribution to the Study of Trypanosomiasis and to the Geographical Distribution of Some of the Blood-sucking Insects, etc. Jour. Trop. Med. & Hyg., 12, Jan. 15, 1909, pp. 15–22. Notes on blood-sucking Diptera and ticks.
Rogers, Leonard. The Transmission of the Trypanosoma evansi by House-flies and Other Experiments Pointing to the Probable Identity of Surra of India and Nagana or Tsetse-fly Disease of Africa. Proc. Roy. Soc., Vol. LXVIII, 1901, pp. 163–170.
Thimm, C.A. Bibliography of Trypanosomiasis ”

“ The forms so carefully studied by Dallinger and Drysdale belong to the genera Bodo, Cercomonas, Tetramitus, Monas, and Dallingeria. Many others are parasites in the blood or internal cavities of higher animals, some apparently harmless, such as Trichomonas vaginalis, parasitic in man, others of singular malignity. Costia necatrix, infesting the epithelial scales of fresh-water fish, often devastates hatcheries. The genus Trypanosoma, Gruby, contributes a number of parasites, giving rise to deadly disease in man and beast. ”