PUBLIC RECORD OFFICE
Reference :-
mwimmimC.O. 885
22 PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC-] COPYRIGHT PHOTOGRAPH-NOT TO
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should say this work will occupy two Medical Officers for from five to six months. The population in Dowa district would probably be more amenable to such an investigation than that of other districts, for the former has already become accus- tomed, to some extent, to such proceedings.
Paragraph 4. This investigation could conveniently be carried on in con- junction with the examination of the 500 natives, provided a sufficient supply of experimental animals could be obtained.
In the case of both these, investigations I would point out the necessity of giving the investigators ample funds for native assistance. At Kasu we had a large number of intelligent natives, who were of the utmost assistance in relieving members of the Commission of much of the work, such as feeding and caring for animals, cleaning apparatus and so forth, work which can be quite satisfactorily accomplished by intelligent natives. It may be well to remark here that the Royal Society Commission had, in addition to Sir David and Lady Bruce, a staff of two Majors, Royal Army Medical Corps, and, for a part of the time, myself, as well as a Non-commissioned Officer, Royal Army Medical Corps, who took charge of all the experimental animals, did most of the inoculation, and took all the blood slides from them, made up all solutions, and had charge of the apparatus and labour supply, and a very competent (white) clerk, who tabulated all the results, drew up charts of results, kept accounts, and made payments. The time of the investi- gators was, therefore, entirely devoted to the actual scientific work, and a con- sideration of the results arrived at by this very well equipped and large body of workers will show that little can be expected of a couple of workers unless well found in the matter of native assistants-an Indian Sub-Assistant Surgeon would probably be of great service in such work as is contemplated. The examination of the slides sent up by the native patrols of the infected area, which at present occupies Dr. Conran's time, could be carried on at the same time.
I might remark that when we had 100 to 120 experimental animals at Kasu the collection of blood slides from them occupied the Non-commissioned Officer, Royal Army Medical Corps, the whole day, and their examination kept the entire scientific staff occupied all day and sometimes part of a second day. It is probable, therefore, that two Medical Officers would find their time fully occupied by testing the results of half that number. Allowing two experimental animals to each native examined, only from 25 to 30 natives could be undertaken on one day. Allowing for the examination of the inoculated animals to be made twice a week, it would be possible to have two sets going at the same time; it would probably be necessary to examine the animals up to three weeks from the time of inoculation. The sub- joined table explains how the system would work, the batches of (inoculated animals from) natives being designated alphabetically, red ink* indicating day of inoculation and commencement of experiment.
Sunday.
Monday. Tuesday. Wednesday. Thursday.
Friday, Saturday,
1st week
B
2nd week
3rd week 4th week
5th week
6th week
7th week
8th week 9th week
AAATCCHHH
AAACCCFHE
SAASAAREE
Batch A completed. Batch B completed.
Batch C completed, Batch completed.
Batch E completed.
Supposing one examined batches of 30 natives, and a sufficient supply of experimental animals was available, this experiment would occupy 26 weeks. On Wednesdays and Saturdays the blood slides from the natives themselves, and from animals indicated in paragraph 4, could be undertaken and the preliminary investigation of the experimental animals. As to the cost of fencing I can form no estimate, but, if undertaken, it is essential that the fencing should be of a durable nature and strong, otherwise it will be quickly demolished by elephant and buffalo and the experiment frustrated. In my opinion a fencing of wood would be quite useless; should it escape bush-buck and fires, white ants and large game would
• Denoted here in italic type.
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make short work of it. As regards the Blantyre-Zomba road, the amount of gaine in that heighbourhood is so small that it seems extremely doubtful whether anyone would avail himself of a relaxation of the game laws, but it could do no harm to relax them.
It appears from the Veterinary Officer's Annual Reports during the past three years that the infection of cattle on the Blantyre-Zomba road has originated at various points, and, in some cases, tsetse fly has been found in the neighbour- hood. The place at which infection has actually occurred seems to me to be of little importance, and to depend, in all probability, on the temporary invasion of the spot by tsetse fly, so that I cannot foresee any useful result from exposing herds of cattle at different points; it would, I think, be of more value to await the outbreak of trypanosomiasis in some estate and then to make a thorough investi- gation of the neighbourhood for tsetse fly, and, if found, ascertain experimentally whether or no they are infective; in the event of no tsetse being found, experiments to determine the power of other biting flies in the neighbourhood to carry infection might usefully be carried out.
It is, I think, established that during the wet season the distribution of G. morsitans extends with the extension of shade, so that it may well be that, for a time, the fly occasionally invades areas which are normally fly free.
Paragraph 6. It seems to me to be insufficiently realised that a large number of the inhabitants of the Dowa sleeping sickness area are dependent for their water supply upon a small number of wooded streams which, during a great part of the year, dry up and sink into the soil before reaching the lake, and I am strongly of opinion that if the banks of these streams were cleared they would dry up entirely during the dry season on reaching the plain, and the country thereby become uninhabitable; this applies, for instance, to the villages (Matumbas, Ntondas, &c.) on the Chitala stream near the Domira Bay--Dowa road, a neighbourhood which is heavily infested with tsetse, and provided many of the cases of sleeping sickness.
Paragraph 5. If any fencing scheme is to be undertaken the objects in view need to be carefully considered before deciding on the locality. I suppose that the first object is to discover whether tsetse fly would remain in the fenced-off area after all game inside had been destroyed or driven off. Should it be found that the fly remain in the enclosure, experiments to ascertain whether they were still infective would be then carried out and, if found to be infective, an attempt to ascertain the source of their infection would be made. In order, therefore, to obtain any useful information from the carrying out of the scheme, preliminary investigations into the trypanosomes carried by the fly, the percentage of flies infected, the per- centage of game infected, and the nature of the trypanosomes in the game, and also the incidence of human trypanosomiasis in the enclosed area, would be required for comparison with subsequent observations: this information is available in Nyasaland only with regard to the infected area of Dowa district.
Should fly remain in the enclosed area in the absence of game, the next step would be to clear the area and again observe the effect on the fly. It is obviously desirable, if considerable expense is to be incurred in fencing some locality, that, apart from the information obtained thereby, some important route should, if possible, be opened up, and in this respect that part of the Zomba-Ncheu road which passes through fly country seems to be the obvious locality for the experi ment. Against this locality are the facts that a fence for many miles on either side of the road, both east and west of the Shire, would be necessary, and that the preliminary information referred to above is not forthcoming for this area. Against the Dowa area are two points: firstly, that the road from Domira Bay to Mvera is of little importance, and secondly, that here, again, a fence for many miles (about 20) on either side of the road would be required. Probably the most economical locality would be the peninsula separating the south-west arm from the main body of the lake; here, again, preliminary information about the fly game is lacking, and the enclosed area is of no particular importance. It does not seem. therefore, that in Nyasaland there is any locality where the experiment could use- fully and economically be carried out; compact isolated areas of fly country which could readily be fenced off are non-existent.
It appears to me that the most that can be done, in the Dowa sleeping sickness area at any rate, is to encourage, in every way clearing around villages, and to discourage the making of gardens at a distance from villages in the bush. It
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