CO885-(16-18) — Page 847

PUBLIC RECORD

OFFICE

Reference :-

mmimmmm C.O.885

18 PUBLIC RECORD OFFICE, LONDON

ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO

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Perhaps the most striking fact in connection with the distribution of Glossina palpalis and the spread of sleeping sickness is the enormous amount of traffic which is shown to have existed and to exist still, though in less degree, between the whole extent of the shores of Lake Victoria and the natives of from 10 to 20 or even 30 miles and more of the hinterland. This fact is apparent when we consider the extreme narrowness of the average fly-range, the few instances (scarcely any, except in South Usoga) in which the fly penetrates inland along the streams, and the distance (not very wide but vast as compared with the few hundred yards of fly- range) to which the epidemic has spread from the lake. The percentage of the infection varies, as one would expect, with the distance from the fly-ranges, and is most marked within the first four or five miles, sometimes considerable within 10, while, beyond this, it is much less, though quite noticeable in places.

We find a decidedly high percentage in many villages which are situated near the lake but outside the fly-range, and this decreases with the distance from the lake and inversely as the amount of traffic therewith, supposing the traffic to be with the infective areas. Some villages situated just outside the local fly-range (which generally means that their water-supply happens to be free) show a high rate of infection because the occupation of practically all their inhabitants is fishing. Many others are connected with the fly-range only through their water-supply, and some through the occupation of canoeing.

It is clear, then, that before all things these two conditions, the width of the fly-ranges and the traffic with the fly-ranges, must be considered in dealing with the spread of infection, and full consideration is, therefore, given to them in the suggestions and recommendations put forward in this report.

For example, water-supplies or dipping-places and also canoe-landings can often be rendered safe by clearing and this, therefore, can be recommended where it is necessary and practicable; or they can be closed and, in certain instances, safe ones instituted. In the case of fishing, however, unless in a few more favoured localities, nothing practical that we can do can make this safe as an occupation, so that I recommend later on its total discouragement or disuse, except in special areas or cases in which it may be found possible to regulate it satisfactorily, and this more especially since a great part of the trade and traffic with the lake-shore is connected with fish.

It appears to me that, so far as we have gone at present in our studies of sleeping sickness in the human subject and inoculated animals, and of Glossina palpalis, its habits and distribution, all things combine to indicate the importance, whatever may be the outcome of the arduous search for an organic or medicinal cure, of the study of prevention and of the necessity for directing our immediate endeavours towards determining, by adequate trial and experiment, what general preventive measures may be practicable in the countries and under the conditions where the disease exists, and, further, that we should seriously consider the advisa- bility of applying, without further delay and to the best of our knowledge, such measures as appear to give the greatest chance of success. For, even if a cure be ultimately found, it is extremely unlikely to be of such general efficacy and applica- bility as to render preventive measures of less than the first importance in controlling the spread of the infection, since it must be remembered that it has been by such means, and not by medicinal cures, that the greatest and most permanent success has been achieved in the past in combating other deadly epidemic diseases such as plague, cholera, typhus, and enteric fever, and that none of these diseases has been overcome, as it were, in pitched battle, but in each case by continued effort and the gradual diminution of its power of attack, the success at present obtained being probably, in most cases, far beyond the hope or imagination of those who began the contest.

If, after reviewing all the facts, it should be decided that the probability is against the success of general preventive measures, or that their application would be impossible, then it would be better at once to cease spending time and money in this direction beyond what is necessary for the protection of certain limited areas, such as European stations, &c., and to await in patience the discovery of an undoubted and effectual cure.

It is my firm belief, however, that the present position as regards prevention, though beset with difficulties, is very far from being hopeless, and that the measures herein recommended would eventually be rewarded with a valuable proportion of

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success in the Uganda Protectorate, though it may be some considerable time before they can be fully applied and before they can produce any very marked effects.

Every one knows that we cannot, in the nature of things, hope to cut short a great epidemic of sleeping sickness with the promptness with which we might check an outbreak of an acute and rapid disease like small-pox or plague, but I believe that, nevertheless, we ought to set out on the same lines at once and on all hands to try, by all practical means in our power, to diminish the chances of infection just as we do in the case of all other infectious diseases.

No doubt certain preventive measures most valuable in other epidemics, such as isolation of the sick, quarantine and cordons, have, owing to the peculiar characteristics of sleeping sickness, been evidently from the first impracticable of anything like general application. Yet, if the bulk of the population with which we have to deal were Europeans, the task of prevention would be comparatively easy, and I believe that our main difficulty will lie, not so much in the great differences of sleeping sickness from other epidemic diseases, as in the peculiarities, prejudices, and, worst of all, unreasoning apathy of the peoples whom it attacks and the conditions in which many of them are accustomed to live, so that our main duty, therefore, is to determine what measures there are which may remain open to us for diminishing the risks of infection, and what prospects of success we may hope for in applying these among such people.

As has before been mentioned, the Sleeping Sickness Extended Investigations have everywhere tended to strengthen the association of epidemic sleeping sickness with the presence of Glossina palpalis and even, to that extent, to indicate it as the sole carrier of Trypanosoma gambiense. The infection, though carried from person to person by the fly, is, as a general rule, conveyed from place to place by man, so that the process of its spread must be regarded from these two aspects. So also its transmission between vertebrate hosts, being indirect by means of the invertebrate, must be considered from two points of view:-

(1) Infection of human beings by infected flies.

(2) Infection of flies by infected persons.

The fly, if kept from contact with infected persons, is harmless, and the infected person, if kept from contact with the fly, is also harmless.

How, then, can we limit the natural possibilities of infection in each case? Broadly speaking, our objects can be attained:—

(A), By diminishing the chances of exposure of human beings to the fly, especially of the sick, i.e., by diminishing the opportunities of the fly for biting them.

(B) By exterminating or reducing in numbers the fly,* especially in places

of human concourse or traffic.

(C) By diminishing the chances of infection being carried by infected per-

sons to or from epidemic or potential epidemic areas.

The chief measures to be discussed or recommended in relation to these various objects will interact to a great extent, but those which are more special to each are as follows:-

A. (1) Local segregation of the sick (Note I.), including deportation with

or without local concentration.

(2) Removal of luts, villages, markets, &c., from within the local fly-

range.

(3) Protection of the person by clothing (including education of natives

to resist and avoid the bite of the fly).

(4) Regulation or selection of hours for certain occupations within the fly-

range.

(5) Protection of employees exposed in their occupation to the attacks of

the fly.

B.-(1) Directly by killing or catching the flies.

(2) Possibly by introducing some destructive animal, morbific or para-

sitic agent among the flies.

Including, of course, the larva or pup, should this become practicable.

D

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