CO885-(18-19) — Page 5

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this fore-shore both soon after the captures commenced and also a short time before it was recently cleared of undergrowth, when I could perceive no difference in the number of flies, which were still very plentiful. After the clearing, however, the boys had to change their hunting grounds to an uncleared part further up the bay in order to obtain specimens.

With regard to the possibility of introducing some destructive animal agency, disease or parasite among the flies, I am not aware that any experiments have yet been attempted in this direction.

As to the possibility of reducing the number of flies locally by limiting their food-supply, this is to a certain extent accomplished incidentally wherever human dwelling are removed beyond the fly-range and wherever places of human concourse or traffic therein are cleared of undergrowth and the opportunities of the fly for feeding on human being are curtailed. I have mentioned that it has been observed that such places as native markets on or very near to the lake-shore are infested by swarms of flies, and that similar swarms are found at the habitual shore-resorts of such animals as hippopotami and crocodiles, probably as a result of a plentiful food-supply. Such haunts of these animals, therefore, as exist anywhere near human settlements or traffic-routes should be cleared and the animals either killed off or driven away and, since Glossina palpalis seems to be omnivorous as far as vertebrate blood is concerned, any vertebrate which may be found to offer it special opportunities for feeding should be got rid of, as far as possible, in like manner.

One of the first measures which occurs to one for the prevention of the spread of epidemies is the closure, complete or partial, of traffic-routes, but this is impos- In the first place it could not be sible in the present instance for special reasons. satisfactorily carried out, or could not be prolonged over a sufficient period, for the same reason that quarantine is inapplicable, namely, the long and indefinite duration, amounting sometimes to years, of the infection in human beings. Another reason is that it appears, so far as one can tell at present, impossible to find alter- native`main traffic-routes (Note 6)* which would have any prospect of being safer than those now in use, and that to open up new routes which are equally infested Then, again, by fly would but widen the spread of infection in the long run. practically all the more important traffic of the country is unavoidably connected Somewhere or other with infected districts, and practically all the internal transport is done by porters who either are, or have been at some time, living in contact with epidemic areas. I may explain that, in speaking of traffic, the intercommunication between the natives themselves, whether for trade or other purposes, is included and forms, probably, a far larger proportion of the whole than that pertaining to non- native traders and travellers, and that of the Government combined. This would never be stopped nor to any great extent controlled by closing roads, but would filter through the country to the same extent as before and through more numerous and often more dangerous channels.

Probably the best, that can be done in this direction is to establish some sort of control, by medical inspection and surveillance, of native travellers, traders and emigrants from epidemic areas, and especially such as wish to pass through or remain in districts in which the fly exists but has not yet been infected. In all such potential epidemic areas, if there remain any in the Uganda Protectorate, as is possible in the case of the northern part of Nile Province and the region round Lake Albert Edward, it is very necessary that precautions should be taken; and emigrants, visitors and travellers should, wherever possible, be kept from contact with the fly-ranges in the same manner as is recommended for segregation of the sick, e.g., by clearing ferries, fords, &c., on the main approaches; by fixing markets in the fly-free localities, as, for instance, the salt market in Toro. Like precautions should be taken in all places where efforts are being made by clearing and otherwise to stamp out the disease.

As regards the traffic-routes themselves, they have already been spoken of with reference to clearing. It must be borne in mind that roads do not pass through wide fly-belts but they are infected, or liable to become so, in spots, strips and small patches, where they pass through or come in contact with fly-ranges on the borders of streams or lakes. The most practical plan seems to be to regulate and improve the present routes as far as possible and, in opening up new ones, to take every precaution in advance to make them as safe as circumstances will allow. In im

• NOTE 6-1 allude to the internal traffic routes of the Uganda Protectorate.

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proving the present routes diversions may be feasible at some points, clearing will be necessary at others, especially at such fords, ferries, landings, camps and water- ing-places as the fly infosts. In water-traffic the course should be, wherever possible, at least 50 yards from any shore or bank where the fly is known or believed to exist, and camping-places and fuel-stations should be carefully chosen and cleared, not only regular but also emergency camps being prepared, especially where sailing-vessels are in use. Another necessary precaution will be clearing of roads from camps to the villages where the porters' or sailors' food is obtained, if the way lies anywhere near the waterside, and it might be arranged that their food should be brought into camp wherever this is possible.

It is necessary, perhaps, to point out the fact that, in clearing a station or settlement or a ford or ferry on a traffic route, the total abolition of every fly would, in many of the worst places, require more extensive clearing than has been recom- mended above, for stray flies may be brought in occasionally by native traffic through the bush, or, possibly, might wander, in some places, from neighbouring breeding- grounds. These last, however, we hope in the near future to be able to locate and to deal with much more casily and radically than is the case at present. To banish the swarms of flies that at present infest such places in many instances is, however, comparatively simple, and we must remember that an occasional fly will neither cause nor serve to keep in progress a great epidemic, and that the risks of infection will be enormously diminished by such measures as have been recommended. The main difficulty will be the up-keep of the clearings which have once been under- taken, and this should be, with proper supervision, a constantly decreasing labour and expense as time goes on.

In conclusion, I may add that my personal opinion, which, though it may seem optimistic to many, is based on long and careful observation of the distribution and habits of the fly and of the distribution and extension of the epidemic, is that, in the Uganda Protectorate at all events, it is possible to control the spread of infection to a large extent and that, if it were not for the natural indolence, indifference and want of confidence in the natives themselves, the task would be far less onerous than it is likely to prove as things are. The natives, however, or at any rate the bulk of them, must eventually come to appreciate the wisdom of our advice and of our actions. When these begin to be attended by successful results they will cease to distrust our motives so that, if the present epidemic can once be checked, any future outbreak beyond those endemic centres which are unhappily almost certain to remain should be controllable with comparative ease.

I will now summarise the foregoing report very briefly as follows :—

1. The mapping of the distribution of Glossina palpalis in the Uganda Protectorate is practically complete, for, wherever it is not yet mapped, the physical conditions of its habitat are sufficiently well known to enable us to say with certainty whether or not the fly is likely to be found.

2. The distribution of sleeping sickness, which was pretty well known before, except in the case of the Nile Province and the small epidemic near Elgon, has been confirmed, and the observations appear to connect the disease more closely than ever with Glossina palpalis.

3. Broadly speaking the degree of infection and the distance of penetration (other things being equal) into the hinterland is everywhere propor- tionate to the intensity of the infection and the prevalence of fly at the corresponding lake-shore or river-side.

4. The enquiry has shown the limited extent of the "infective areas,” in which alone sleeping sickness is communicable to man, and the wide extent of the fly-free interior, in which it is not communicable.

5. The "infective areas" form a very small proportion of the epidemic areas and the bulk of human infections is due to communication with these areas, while only a small minority is caused by actual residence within them.

6. Investigation shows also the efficacy of clearing when scientifically applied, the apparent feasibility of segregation and the importance of obtain- ing native co-operation if possible.

"natural" range of

7. By clearing or otherwise destroying the narrow

Glossina palpalis the wider "following" range is abolished.

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