Other species of Glossina, e.g., G. morsitans and G. tac/iinoides, become similarly infected. But some species rarely attack man.
In 1909 a second species of trypanosome was discovered in a case of human infection from Rhodesia and called T. rhodesiense. It is found in areas infested not by G. palpalis but by G. morsitans, and was shown by King horn and Yorke (I 91I) to be conveyed by this species and to undergo in it a similar development. T. rhodesiense infections are found in Nyasaland, Portuguese East Africa and Tanganyika Territory, besides northern Rhodesia, and, rarely, south of the Zambezi river. T. rhodesiense cannot be distinguished from T. gambiense by its appearance in human blood; after inoculation into animals microscopical differences can be detected; since such inoculations are rarely made it may be more often the cause of sleeping-sickness than is believed : its carrier is widely dis tributed. Indeed, a few cases have been found as far north as the Anglo-Egyptian Sudan; and near Mwanza, south of Lake Victoria, a small epidemic occurred in 1922, conveyed by a tsetse akin to G. morsitans. This type of human trypanosomiasis is rarely epidemic; cases occur in sporadic fashion. It is more acute and more rapidly fatal than the T. gambiense variety, and is more resistant to drugs. Whether or not T. rhodesiense is identical with T. brucei the parasite of nagana, first described by Bruce in Zululand (1893), is undecided. Bruce and Yorke con sider them to be the same ; Kleine makes a distinction. They cannot be separated by their appearance under the microscope, the symptoms and course of the illness produced in animals, or the manner and site of development in the tsetse. Both com plete their development in the salivary glands.
T. brucei and T. rhodesiense are found in big game, especially waterbuck, bushbuck, reedbuck, haartebeest, on which G. mor sitans feeds. These animals are, therefore, reservoirs of germs capable of infecting man, and much discussion has taken place as to the role played by big game in the spread of T. rhodesiense, some claiming that the passage of the parasite is game, fly, man; others that it is man, fly, man. The point is still undecided.
An experiment was made in East Africa during the World War in which blood was taken from transport animals infected with T. brucei and inoculated by Taute into himself, his colleague Huber and 127 natives. Though animals inoculated at the same time always became infected there was no single instance of infection in man. They concluded that man is immune to infec tion by T. brucei. This striking experiment, however, does not convince those who believe man to be susceptible but very resistant of T. gambiense, it is generally agreed that infected man is the chief reservoir of infection, though Bruce (1911) found that antelopes can be infected with this trypanosome by allowing infected palpalis to feed upon them, and they continue to harbour the trypanosomes in their blood for many months.
Sleeping-sickness is now treated by compounds of arsenic, especially atoxyl and tryparsamide, the latter a prod uct of the Rockefeller Institute; by compounds of antimony, as tartar emetic ; and by a drug of undisclosed composition called Bayer 205, or Germanin. The French and Belgians use atoxyl largely in the African villages, where doses are injected at the proper intervals by trained natives. A high degree of success is claimed, both curative and preventive, in that the blood is kept free from germs which might be taken up by the tsetse. Anti monials are used as a rule in conjunction or alternation with arsenicals. Bayer 205, first employed in the treatment of man in 1921, has remarkable successes to its credit in Europeans, especially in cases of the Rhodesian type which were refractory to other drugs; unless used with caution it has a harmful effect on the kidneys. It has been less successful in natives, perhaps be cause infection is usually detected in them at a later stage when the spinal cord and brain are affected, and at this stage treatment nearly always fails. French chemists have prepared the same or a similar drug. Tryparsamide, introduced about the same time, appears to be still more potent, and especially in cases in which the nervous system is involved, but it also has a serious effect in that it sometimes affects vision. Though sleeping-sick ness in the European is nearly always a fatal disease if left un treated, in the natives of parts of Africa it is very chronic, does not interfere with the patient's activities, and almost certainly may end in natural recovery.
At the suggestion of the League of Nations an International Conference on Sleeping Sickness met in London in 1925. In its recommendations it laid down administrative measures which should be taken on both sides of the frontiers between infected countries for the control of the disease, and advised the dispatch to Uganda of a commis sion to study the problem. The commission started work in 1926 and in 1927 issued an interim report. The programme is divided into Epidemeological Studies and Laboratory Work. The conclu sions so far are tentative only.
of the Interdepartmental Committee on
H.M.S.O., London, Cd. 7349 (1914) Sir David Bruce, "Croonian Lectures," Lancet (June and July 1915) ; B. Black lock and W. Yorke, "The Trypanosomiases," in W. Byam and R. G. Archibald's Practice of Medicine in the Tropics, vol. 2 (1922) ; also Tropical Diseases Bulletin, Tropical Diseases Bureau (London 1912 25). Interim report of the League of Nations International Commis sion on Human Trypanosomiasis, C.H. 536, 1927, Geneva. All the sci entific publications on sleeping sickness are abstracted in this periodical.