174 EBViBW — Tnoi'icAr. medicine, etc. 



Sleeping had contracted the disease from their husbands, all of whom had died of sleeping sickness. 



Sickness— When sleeping sickness was found in villages outside the glossina belt, women only were 

 i-;iit!,iiiol found to bo infected, the children and men who had not visited sleeping sickness districts 

 being unaffected. In one case the three wives of a man suffering from sleeping sickness 

 contracted the disease. As has since been pointed out, if the converse can take place and 

 males be infected by females, it is quite possible that the tsetse fiy is only an occasional 

 agent of transmission, and the outlook, therefore, very grave. 



The above-mentioned French observers point out that Koch's views do not explain 

 certain cases observed by them. They have never found the disease linjited to married 

 women, and, as stated, have often found young children affected. At the same time, they 

 noted liow the disease spreads amongst families and how the natives of the French Congo 

 dread infection by contagion and take measures to isolate the sick. 



The question as to whether or not the trypanosome passes a stage of its life cycle 

 in (t. palpalis still remains unsettled, despite the work of Minchin and his colleagues. 



Koch lays stress on the fact that on two occasions parasites have been found in the 

 salivary glands of the fly and on the presence of several forms of T. gamhiense in its 

 alimentary canal. He, therefore, believes that such a developmental cycle exists. How 

 long a glossina can remain infective is not known, and this is a question which requires 

 to be settled at an early date. Koch believes the fly to be long-lived, as it is not known 

 to have any natural enemy, while its reproductive energy is feeble. 



Minchin' found that the capability of infecting a vertebrate animal only lasts for a 

 period of 48 hours ; with a longer interval no infection was obtained. It was also noticed 

 that freshly-caught flies may produce infection with trypanosomes without having been 

 fed previously on infected animals. Experiments made upon monkeys show that many 

 freshly-caught flies are either free from the infecting agent or that some monkeys are 

 immune. Thus in one case 2299 flies were fed on a monkey over a long period without 

 infecting it, whilst in another case as small a number as 134 flies produced an infection 

 in it. Wlien infection did take place it occurred much more rapidly with the freshly- 

 caught flies than with those that had been fed upon animals infected with trypanosomes. 

 In experiments made with flies fed on an infected animal, Minchin found that he could 

 infect nine out of ten animals each with a single fly. 



Hodges,'- in his very valuable Uganda Report, deals with the source whence the fly 

 may derive the trypanosome. He says : — 



Although vertebrates of various kinds have been artificially inoculated with T njpanosotiia gnnMense, 

 yet, so far as is known at present, there is no wild or domestic animal which, itself almost or quite inimuuo, 

 carries this Trypanosoma so habitually as to act as a "reservoir" for the infection of sleeping sickness, as do 

 the big game in the case of the Trypanosoma hrucei, of Nagana. No animal, indeed, except the native dog, 

 and that in only a few instances, in places where the degree of local infection has been intense and the 

 epidemic has been of considerable duration, has been found to be naturally infected ; on this point, however, 

 further research is much needed, for, if there be such a reservoir, it is most likely a domestic animal, and 

 might possibly be the native dog itself ; at any r.ate, it is unlikely to be an animal which ranges, and would 

 therefore carry the infection, very widely. It is obvious that animals which can become natnrally infected 

 by Qlossina pa/palis, unless the fact is very exceptional, arc an added danger to the community. 



Meantime we must provisionally suppose that only the human being and the fly need be seriously considered 

 as agents in the spread of infection, that the vast majority of flies, where human licings are scanty or absent, are 

 uninfected and harmless in themselves, and that, if the fly could be eliminated from places of human concourse 

 such as mentioned above, those existing elsewhere would run little chance of becoming infected. 



He also suggests that it is even possible, still, that the conveyance of the infection by 

 Glossina palpalis, rather than by other Glossiiuv, or by any blood-sucking insects, may be 

 merely owing to a prolonged viability of the trypanosome in the interior of this fly ; that a 

 migration rather than an evolution takes place, and that it is not a true host. 



Manson^ brings forward an interesting point in a recent paper, by saying that : — 

 It is not a little remarkable that, of the ten cases of trypanosomiasis in Europeans which have come under 

 my personal observation, three of them were females. Considering the very small number of European females 

 and relatively large number of European males in tropical Africa, this large number of females attacked with 

 trypanosomiasis is a striking circumstance. I am dealing, it is true, with very small numbers, and it is quite 

 possible that the relative disproportion I remark on is accidental ; but when we reflect that whereas women in 

 Africa expose themselves, as compared to men, comparatively little to the conditions favouring the attack of 

 Ohsxina palpalis, the disproportion becomes still more striking. 



> Minchin, E. A. (March, 1908). Quarterly Journal of Microscopical Science. 



■ Hodges, A. D. P. (December 22nd, 1908). Report of P.M.O. East Africa and Uganda Protectorates, p. 19. 



» Manson, Sir P. (March 2nd, 1908), " My Experience of Trypanosomiasis in Europeans, and its Treatment 

 by Atoxyl and other Drugs." Annals of Tropical Mnlicine awl Parasilnlofiy, Series T.M., Vol. II., No. 1. 



