Trypanosomiasis

“ By trypanosomiasis is meant a condition of animal parasitism, common to man and the lower animals, in which trypanosomes, peculiar flagellate protozoa, infest the blood. Depending upon the species, they may be harmless, producing no appreciable ill-effect, or pathogenic, giving rise to conditions of disease. ”

“ It is especially observable in those more chronic forms of trypanosomiasis of man and animals, in which the trypanosomes disappear from the blood for considerable periods at a time, and may explain the occasional infectivity of blood in which the parasite cannot be detected with the microscope. ”

“ It is also known as the human trypanosomiasis of Brazil, South American trypanosomiasis, and Chagas’ disease.
Chagas88 reports two principal forms—acute and chronic. The acute infection is rare, and is characterized by increase in the volume of the thyroid gland, pyrexia, a sensation of crackling in the skin, enlarged lymphatic glands in the neck, axilla, etc., while the liver and spleen are increased in volume. Sclerosis of the thyroid gland is found at autopsy and fatty degeneration of the liver. During an attack of fever, trypanosomes are found in the blood. ”

“ 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." ”

“ Experiment has shown that the glossina will bite any vertebrate, and that it can infect a large variety of mammals with the trypanosome. If this be the case in the laboratory it is reasonable to suppose that it is the case in nature also. Therefore, in the endemic regions of trypanosomiasis, the vertebrate fauna has to be reckoned with as a source and reservoir of infection. ”

“ 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 ”

“ 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. ”

“ In this country, and indeed in temperate zones generally, there is no dread of trypanosomes, and 'sleeping sickness' is more often the subject of thoughtless jest than of intelligent consideration. In England, where African interests are more keenly followed, a deep interest is taken in this matter, and the Liverpool School of Tropical Medicine deals largely with trypanosomiasis. ”

“ Movements of infected individuals towards hitherto uninfected countries must necessarily be attended with great risk of the introduction of the disease. Whether such movements can be prevented in savage lands depends greatly on local circumstances. Wherever possible they should be prevented. Dutton and Todd suggest that an easily ascertained condition, more or less general in trypanosomiasis, namely, enlargement of the cervical glands, should be employed in eliminating dangerous individuals. ”

“ 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 ”

“ 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. ”

“ Gradually increasing mental deterioration marks the almost invariable course to death. A more virulent type of trypanosomiasis is found in Rhodesia.
In Brazil there is a disease caused by a flagellate, Schizotrypanum cruzi, which resembles a trypanosome and is transmitted by a bug, Lamus megistus. The disease runs an acute course with a high fever and great mortality in infants showing chiefly manifestations of involvement of brain or thyroid gland. In adults it runs a chronic course showing neurological manifestations or signs of myxoedema or even of Addison’s disease. ”

“ The idea of cure must not be entertained until the patient has been free from all symptoms for many months, nor until the repeated injection of several cubic centimetres of his blood has failed to induce trypanosomiasis in susceptible animals. ”

“ Exophthalmos was noted 16 times. ↑ * The Wassermann reaction is of little avail, as unfortunately the sera of most cases of trypanosomiasis give a positive result. ↑ * Broden and Rodhain report good results on the Congo by intravenous injection of salvarsan; they insist that it is only of benefit in those cases where invasion of the spinal cord is negatived by microscopical examination of the spinal fluid. ↑ * Duke has tried the injection of prophylactic doses of arseno-phenylglycin in the monkey and subsequent development of the trypanosome in the tse-tse fly. ”

“ As regards personal prophylaxis, white clothes are to be worn as the tsetse fly, along with mosquitoes, prefers dark-colored garments. The [79] legs should be protected by leggings and possibly one could consider the wearing of gloves or veils. As a matter of fact, however, the heat of the tropics precludes these latter measures. As the fly only bites in the daytime one should choose the night for going about, if practicable.
Treatment.—The general opinion is that trypanosomiasis is only curable at a time prior to the appearance of trypanosomes in the cerebro-spinal fluid. ”

“ Trypanosomiasis in man, the 'sleeping sickness,' which occurs on the west coast of Africa, particularly in the basin of the Congo, has within the last few years spread eastward into Uganda, has already swept off some hundreds of thousands of victims, is spreading down the Nile, has spread all round the shores of Lake Victoria and is still spreading southward round lakes Albert and Albert Edward, and now threatens the Transvaal and Zululand. ”

“ In the treatment of trypanosomiasis, concurrently with the use of drugs, every effort should be made to keep the patient in good general health. Rest, warmth, and residence in a cool and healthy climate, the systematic use of quinine for any concurrent malarial infection, and the avoidance of fatigue and everything that might depress, should be insisted on. ”

“ To settle these and other questions of great practical importance in connection with the role of the tse-tse fly in trypanosomiasis, experiments with laboratory- reared insects are indispensable; and, further, observations should be extended to all the species of the genus. We have no assurance that Glossina palpalis and G. morsitans are the only efficient transmitters. Direct infection through breaches of surface or through mucous membranes (e.g. during coitus, as has been suggested by Koch) cannot be entirely excluded as a possibility. ”

“ African Trypanosomiasis - caused by the parasitic protozoa Trypanosoma; transmitted to humans via the bite of bloodsucking Tsetse flies; infection leads to malaise and irregular fevers and, in advanced cases when the parasites invade the central nervous system, coma and death; endemic in 36 countries of sub-Saharan Africa; cattle and wild animals act as reservoir hosts for the parasites. ”

“ Todd, J.L. A Note on Recent Trypanosome Transmission Experiments. Jour. Trop. Med. & Hyg., 12, Sept., 1909, p. 260. Show that they develop in G. palpalis when taken from their mammal host at the proper stage of development.
Woodcock, H.M. The Hæmoflagellates: a Review of Present Knowledge Relating to the Trypanosomes and Allied Forms. Quar. Jour. Micro. Sci., Vol. 50, 1906, pp. 151–331. Characteristics; mode of infection; effects on host; biological considerations; life-cycle, etc. Spirochaetæ; bibliography. Important article.
Trypanosomiasis and Sleeping Sickness. Jour. Trop. Med. ”

“ Probable synonyms.—Trypanosoma dimorphon, Laveran and Mesnil, 1904; Trypanosoma nanum, Laveran, 1905; Trypanosoma pecorum, Bruce, 1910; Trypanosoma confusum, Montgomery, 1909.
This trypanosome causes disease among horses (e.g., Gambia horse sickness) , cattle, sheep, goats, pigs, and dogs. It is widely distributed in Central Africa (e.g., Gambia, Congo, Uganda, Nyasaland) , the strain probably being maintained naturally in big game. It is transmitted by various Glossinæ, and perhaps by Tabanus and Stomoxys. It is said to develop in the gut and proboscis of Glossina palpalis and G. morsitans. ”

“ 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. ”

“ This species has been shown by Kinghorn and Yorke, and also by Bruce, to be responsible for the transmission of Trypanosoma rhodesiense, the micro-organism producing sleeping sickness in man in Rhodesia and Nyasaland and also in parts of German and Portuguese East Africa. Fisher and Taute have demonstrated experimentally that Trypanosoma gambiense—the sleeping sickness parasite of other parts of Africa—may also be transmitted by this fly, and in addition it is known to be capable of disseminating several species of trypanosomes pathogenic to animals. ”

“ Similarly with regard to the many other pathogenic Trypanosomes now known, there is undoubtedly, in each case, some indigenous wild animal tolerant of that particular form, which serves as a “latent source of supply” to strange mammals.
The transmission of the parasites from one vertebrate individual to another is effected, in the great majority of cases [3] by a blood-sucking invertebrate, and by this means minion; alone. The “carrier” of a Trypanosome of warm-blooded vertebrates is, in all instances so far described,Transmission: Alterations of Hosts. ”

“ 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. ”

“ 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. ”

“ Very many of the common domestic mammals can be successfully infected (either thus accidentally or else on purpose) with different “pathogenic” Trypanosomes, to which they succumb more or less readily, but they cannot be regarded as the natural hosts of those Trypanosomes. In dealing with disease-causing forms, the more narrowly the original source of the parasite concerned is defined, the closer do we get to the true vertebrate host or hosts. ”

“ 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. ”