PUBLIC RECORD OFFICE
Reference :-
CO. 885
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC. COPYRIGHT PHOTOGRAPH-NOT TO
22 PUBLIC RECORD OFFICE, LONDON
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square miles, and that this area must be effectively fenced in order to prevent the return of the game, and that the experiment will extend over three years.
Estimated Expenditure:-
(1) Observations on the seasonal variations of the locality selected for at least one year before the commencement of the experiment
(2) Fencing.-Original double fence, 100 miles at £50 per mile
Repairs to fencing during the continuation of the experiment, including material, white and native labour, for at least two years
£500 5,000
2,000
(3) Quarters.-Erection and maintenance of quarters for European
Staff
500
50
(4) Salary of trained observers (Microscopist and Entomologist) engaged in observations as to the results
2,000
(5) Transport
400
(6) Removal of Game
100
300
£11,350
For Native Staff
(7) Incidental Expenses
Estimated total expenditure
II. One or other of the following conditions will be found to result from the experiment:
(a) The total absence of fly from the area cleared of game. (b) A diminution in the amount of fly present.
(c) Unchanged conditions as regards the prevalence of fly.
III. The Interpretation of these Results. (a) and (b). In the event of either
of these results being found to have followed the removal or destruction of game within a given area it will then be necessary to determine-
(1) Whether the fly has died as the result of the removal of one of its sources
of food supply; or
(2) Whether the fly has migrated in search of food.
Until a method for the determination of these essential points be available an experiment giving these results will be open to grave doubts.
(c) The finding of apparently unchanged conditions after the removal of the game will also not be in any sense conclusive as to the result of the experiment.
The bionomics of this fly are as yet but little known. There are reasons to suppose that more than one condition is required for its suitable habitat. At least two conditions may be regarded as essential, namely, a food supply and a suitable breeding ground; one locality may provide one condition, another adjacent one the other. The locality selected for this experiment will in all probability provide both
On the completion of the experiment food will be sought for elsewhere, possibly where it exists alone. The area over which the experiment was carried out may still be utilised as a breeding ground; this will necessitate a constant interchange of the insects according as to whether they are in search of one or other condition, and little, if any, information will be gained from the results of game destruction on the numbers of the flies.
(In carrying out this experiment over a limited and properly fenced area it does not seem necessary that the game should be destroyed. Results which will prove to be at least equally instructive could be gained by driving the game from the area under observation.)
A study, therefore, of all the circumstances bearing on the experimental destruc- tion or removal of the game from a selected area owing to the large expenditure involved, our present ignorance of the bionomics of this fly, and, therefore, our inability to correctly interpret the results following this experiment, does not lead to the opinion that this experiment would be justified by its results.
Our knowledge of the facts bearing on the relationship of sleeping sickness to big game, and our knowledge of the present position of the disease, do not justify the agitation which at present exists for the general destruction of game as a pre- ventative of the spread of this disease.
Until there is definite proof (1) that the disease is spreading; (2) that the game is respnsible for the maintenance of the fly; (3) that the game is the only reservoir of the disease, or even the chief one; and (4) that the conditions following the destruction of the game will be an improvement on those which at present exist, it
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is a reasonable conclusion that the presence of this disease as it now exists does not afford sufficient excuse for killing out the game.
Since the date of the last report on this disease a considerable amount of evidence has been obtained to show that in the eighteen months which have since elapsed there has been no spread of this disease or evidence of a tendency to spread. There is, on the other hand, increasing reason to think that the disease is an old one and has arrived at a condition of equilibrium, i.e., that it is endemic, and in many respects approximates to the conditions found on the west coast, and that sporadic cases only will continue to be found.
For
Its present condition, therefore, requires no hasty or drastic measures extirpating the living reservoirs of sleeping sickness," the grounds for which are purely hypothetical and unreliable. All that is required to meet the present situa- tion is a continuation of the work on the lines recommended in the Sleeping Sickness Report for this Territory, February, 1912, which were as follows (page 27) :-
(1) Natives in fly areas should be prohibited from keeping domestic animals, goats, sheep, dogs, &c.
(2) That they should be encouraged by means of trapping, pits, drives, and, if possible, in being allowed a certain number of firearms, to clear the vicinity of all villages in fly country of game, and that, except in the vicinity of villages, game should be as far as possible unmolested in order to prevent their movement into areas free of infection.
(3) That natives should be encouraged to protect all cultivated lands by means of cuttings or clearings from fire, with the object of allowing a more complete clearance to be made by means of grass fires. At present in many places the native is reluctant to start a grass fire, owing to the danger of losing his crops thereby.
(4) That the headmen of each village should be encouraged by means of small payments to rid as far as possible the immediate vicinity of his village of fly by means of mechanical appliances for trapping, &c. The details of this work might be under the supervision of the Medical Officer of the district.
(5) That certain routes, to the exclusion of all others, should be used for all natives and others travelling through these areas, and that these routes should, as far as possible, be rendered safe both by the removal of infected cases and by the encouragement of game destruction in their vicinity.
Corrections. A considerable number of errors have crept into discussions and statements which have recently been made in England on the question of the relation- ship of game to the spread of sleeping sickness.
It is advisable that these should be corrected.
(1) There is no reason for supposing, as has been done, that sleeping sickness had not occurred in Rhodesia prior to 1908, when the first case was discovered ("Proceedings of the Zoological Society of London," June, 1913, page 321). There is, on the contrary, very good reason for thinking that the disease had existed there for many years before that time.
(2) The unqualified statement had been made that "sleeping sickness has already crossed the Zambesi." (Ibid, page 328.) The present state of our knowledge offers no justification whatever for what is implied by this statement; it might equally well be said that sleeping sickness had crossed the Zambesi from the south.
(3) The available evidence as to the spread of the disease does not "strongly suggest that during the past few years sleeping sickness has been on the increase (Ibid., page 335); it, on the other hand, shows that the disease has not spread.
(4) It is difficult to understand how the statement that "the most reliable information is to be obtained from the incidence of the disease in Europeans can be qualified. To anyone familiar with this country and local conditions, it is very evident that the incidence of the disease in Europeans bears no relationship whatsoever to its incidence in natives. A devastating epidemic amongst natives might be raging without one per cent, of the European population coming within many hundreds of miles of the possibility of becoming infected.
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(5) The statement that "Since the Luangwa Valley has been closed quite a number of Europeans have contracted the disease in North-Eastern Rhodesia (Ibid., 336) is quite incorrect. Only one case of the disease has occurred since that date.
(6) The opinion has been expressed that "The spread of trypanosomiasis south is a thing that at present no adequate attempts have been made to prevent. ("Trans- actions of the Society of Tropical Medicine and Hygiene.")
33.89
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