PUBLIC RECORD OFFICE
Reference :-
mmmhim C.O. 885
22 PUBLIC RECORD OFFICE, LONDON
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That these remarks are incorrect is sufficiently obvious, and that they could not be made except as the result of ignorance is also obvious. Their object can only be conjectured.
Unqualified and incorrect statements such as the above should not be made. Their publicity gives them an unwarranted significance, their only result is to produce a false impression of what is being done by the Governments concerned, and to embarrass those who, with the advantage of accurate knowledge at their disposal, are responsible for and are carrying out the requisite measures för checking the spread of the disease.
The occurrence of Gl. Morsitans--transmitted Human Trypanosomiasis outside the confines of the present closed Area.
It was stated in the Sleeping Sickness Report, February, 1912, that there was little reason to hope that transmission would be in any way inhibited by the natural conditions existing throughout the territory, and, consequently, that the disease would not prove to be confined to the Luangwa Valley and similar altitudes in Nyasaland, and the instance of the discovery that the disease was transmissible in the Chinunda District (altitude, 3,500 feet) was then quoted (vide page 29).
It has since then been found by Dr. Kinghorn and his co-workers on the Luangwa Sleeping Sickness Commission that temperature exercises a very marked influence on the developmental cycle of T. rhodesiense in Glossina morsitans. High temperatures (75°-85° F) favour the development of the parasites, whilst low temperatures (60°-70° F.) are unfavourable. Cases of the disease have also been found in which the history proved them to be locally infected in various parts of the Territory where these unfavourable conditions exist to a greater degree than in the Luangwa Valley.
The disease has been found by Dr. Ellacombe in the Serenje District to the east of Lake Bangweolo, September, 1912; by Dr. Kinghorn in the Mpika District. May, 1913; by Dr. Ward in the Ndola District, 1912-1913; and by Dr. MacKnight in the Luano Valley, September, 1913.
It may, therefore, be accepted that, although certain unfavourable climatic conditions exist to a more marked extent in some districts than in others, transmission is possible wherever there is tsetse fly.
LUANGWA SLEEPING SICKNESS COMMISSION.
In April, 1912, this Commission was moved from Lawalia, in the Luangwa Valley, to Ngoa (Mpika District), on the Congo-Zambesi watershed, with the object of determining what influence climatic conditions have on the transmission of the parasite by glossina morsitans, and thus determining the possible extent to which the disease could spread.
It was found that—
(1) attempts carried out at laboratory temperature on the Congo-Zambesi plateau during the cold season to transmit the human trypanosome by means of Glossina morsitans were invariably unsuccessful, in spite of the fact that 680 flies were used in these experiments.
(2) "the developmental cycle of T. rhodesiense in Glossina morsitans is, to a marked degree, influenced by the temperature to which the flies are subjected. Low temperatures (60°-70° F.) are unfavourable;"
(3) "the first portion of the developmental cycle can proceed at lower tem- peratures, but for its completion the higher temperatures are essential;"
(4) "the relative humidity of the atmosphere has apparently no influence
on the development of the trypanosome in Glossina morsitans.” The object which determined the formation of this Commission, namely, the incrimination of Glossina morsitans as the carrier of human trypanosomiasis having therefore been accomplished, the work of the Commission came to an end at Ngoa in August, 1912.
Very great credit is due to Dr. Kinghorn and his co-workers, Drs. W. Yorke, A. F. Wallace, and Mr. Ll. Lloyd, for the rapidity and thoroughness with which this work was accomplished
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MODIFICATIONS IN EXISTING SLEEPING SICKNESS REGULATIONS.
LUAPULA, MWERU AND TANGANYIKA AREAS.
The complete removal of the population from all contact with Glossina palpalis has rendered it necessary only to prevent the return of these natives to the Luapula and to the shores of Lake Mweru and Tanganyika. A suggested boundary line embodying this recommendation has already been submitted.
LUANGWA CLOSED AREA.
The regulations at present in force in this area were designed to prevent the spread of a disease which was then thought to be confined to this area (1910). More recently it has been found elsewhere, and there is reason to think that its occurrence is possible wherever Glossina morsitans is found. Transmission, however, being modified by certain climatic conditions, the Luangwa Valley providing more favour- able conditions for its transmission than elsewhere in the territory.
It has been found that, notwithstanding the known presence of infection in the Luangwa Valley for at least six years, and in spite of apparently every necessary condition favourable to its spread being present, there is no evidence of any tendency to spread, and that the tendency of the disease is to assume a sporadic character.
It may, therefore, be expected that, since the disease is not spreading in this area, it will not do so under less favourable conditions. For these reasons it is thought that a continuation of the present stringent rules and regulations governing the movements of natives in the Luangwa closed area are no longer necessary, and that the restrictions consequent on these to trade and development may now be relaxed.
A recommendation has, therefore, been submitted for the modification of these regulations.
ENTOMOLOGICAL.
The following is the general programme of work which has been adopted in connection with the investigations now being carried out :-
(1) Determination of the relative value of various food supplies with reference
to breeding capabilities.
(2) Determination of what parasites affect the fly or pupa.
(3) Further investigations into breeding places and habits, namely:-
Is breeding seasonal?
Are the pupa carefully placed or are they deposited at random?
Are breeding haunts at special places in fly belts which are visited periodically for the purpose of depositing pupæ, or are the pupa deposited throughout the belt?"
Is there any special relation in the breeding places to
Soil?
Water? Shade?
(4) General.-As to food, water, plant juices, invertebrate animals' preferences
in food re small mammals and birds.
(5) Distribution.-Seasonal variations as to shade, water, game, native cultiva- tion, European settlement, reasons for avoidance of certain areas where conditions are apparently favourable.
(6) Enemies.-What animals or insects prey on the fly and its pupæ.
Are there any special enemies apart from parasites (fungi)?
What parasites attack the fly?
What parasites attack the pupa?
(7) Trapping. Is there a reasonable probability of reducing the number of
fly by any form or forms of trapping.
8.
Tsetse Fuges. Are there any such in nature?
The Entomological Staff at present consist of Messrs. Ll. Lloyd, H. C. Dollman, and R. A. F. Eminson.
Mr. Lloyd, since the completion of the work of the Luangwa Sleeping Sickness Commission, has been stationed at Ngoa, Mpika District, and has for the most part been engaged: (1) On the determination of the relative values of the various food supplies with reference to breeding capabilities; and (2) In determining whether Glossina morsitans will feed on small mammals, birds, reptiles, or amphibians.
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