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PUBLIC RECORD OFFICE

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PUBLIC RECORD OFFICE, LONDON

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There are but labour, expended in the right direction, is all that is required. various islands and districts along the mainland shore where so little labour would be required to exterminate the tsetse that the natives would be willing to under- take the task if they would be able to regain all their former rights and privileges thereby. It is the right to build and operate canoes for fishing and other purposes which is most desired. The lands are good, but not much better than plenty of others lying idle in the interior. Only if their water rights are offered as the inducement will the natives cut much bush or exterminate many tsetse.

5. In order to keep them quite away from the fly-infested shores it was found necessary to destroy their canoes and to forbid them building any more for use in the open lake. For the same reason they may not be permitted to build others now. Thus it becomes impossible for any considerable part of the lake shore to be recolonized as long as any other considerable part remains fly infested and the Government adheres and lives up to its accepted policy. Extermination of the taetse everywhere, simultaneously, is wholly impracticable, and a permanent tabu remains the alternative to the revision of the Ordinance and Rules.

6. The reason why it was necessary to forbid the use of canoes upon the open lake was because there were no adequate means of policing so large an area. Inspection has been left largely in the hands of the natives themselves, and only rarely, of late, have European officials been deputed to check up the reports of the native inspectors. An Ordinance so strictly worded, and broadly enforced, is pretty sure to be broadly violated. Innumerable minor violations are overlooked and tacitly permitted.

7. Notwithstanding this, no harm has resulted. The sleeping sickness has decreased to the point of almost disappearing from that part of Uganda where depopulation was seriously attempted.

8. The fact that an Ordinance designed to protect the public against an infectious disease may thus be violated with impunity, at times when infection is still present, is of itself sufficient indication that it might safely be revised along more liberal lines.

9. It is, in fact, very probable that one as liberal in its letter as the present is in its enforcement, and which was strictly enforced, would permit legitimate development of large tracts of land and many good fishing grounds, without exposing the population to infection to any greater extent.

Il-Conditions favourable to an Epidemic of Sleeping Sickness, as indicated by Investigations into the Bionomics of Glossina palpalis.

10. Investigations into the feeding habits and host preferences of Glossina It is palpalis have demonstrated that this fly does not favour man as a host.

It feeds upon man not attracted to inhabited localities, but rather avoids them. only when he trespasses upon its chosen haunts, which are usually clearly defined and easily avoided. It is not specially adapted to transmit disease from man to man, and such transmission thus comes to depend very much on chance.

11. Ordinarily only a small percentage of all the "bites" made by the flies For the disease to be infesting any region will be upon the human host. transmitted it is necessary that the same fly bite the human host more than once. It is, therefore, the percentage of "bites rather than the number which are inflicted upon man which counts in the chances favouring the transmission of the disease.

12. It is readily seen that if, for any reason, the percentage of flies biting man increases n times the chances favouring the transmission of the disease from man to man are likely to increase nearly n2 times.

13. This hypothesis has been put to the test on every possible occasion, and experiment and observation have not merely upheld it but have indicated that the chances will actually increase more than 2 times, because anything which causes more people to go into the localities infested by tsetse tends at the same time to drive away its wild hosts, so that, even though the number of flies may be slightly decreased, both the gross number of bites and the percentage of bites inflicted upon man may increase, and the chances favouring the transmission of disease may thus increase very rapidly.

14. An increase in population would have this effect, and minor changes in the manner of life of the inhabitants of a fly-infested community might have a very marked effect indeed.

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15. If the chances favouring its transmission from man to man are reduced to below certain limits it would become impossible for the micro-organism to increase and disperse as a parasite of man, and it must certainly disappear, or become locally extinct, unless a permanent " reservoir" is found in antelope or some other host.

III.-Antelope as a Reservoir for the Virus of Sleeping Sickness.

16. If other animals, such as antelope, are capable of transmitting the virus of sleeping sickness through fly to man, other than the before mentioned conditions would determine the chances that man contracts infection.

17. Nearly everything which was learned of sleeping sickness during the latter part of the technical investigations indicated that there was a close parallel between it and the trypanosome diseases which are known to be harboured by game and transmitted to cattle by bites of permanently infected flies, usually by Glossina morsitans. The parallel, however, is far from exact.

18. Cattle may never be herded con- tinuously in a region in which Glossina morsitans occurs and feeds (as it must)

upon game.

19. Cattle cannot be herded continu- ously upon the outskirts of morsitans belts where they are exposed to the attack of straggling flies.

20. Cattle cannot be driven in herds through morsitans belts without grave danger that they will contract disease.

21. Cattle wandering or straying into a morsitans belt are in grave danger of contracting infection.

22. As far as I am aware there has never been an epidemic of cattle trypano- somiasis as the result of transmission of the virus from ox to ox by the agency of any species of Glossina, although there have been numerous instances placed on record of infection spreading through a herd, and to neighbouring herds, in which other large biting flies than Glossina appear to have been responsible for its "mechanical" transmission.

A human population continues to occupy parts of the palpalis belt in Fast Africa, and appears to be increasing, although infection has been continuously present.

Large populations have continued to occupy localities along the lake shore in Uganda, where straggling palpalis are more or less common.

Large numbers of natives have been employed for considerable periods in clearing operations, etc., in densely in- fested parts of the palpalis belt, and occasionally in parts of it densely in- fested by flies which feed largely upon antelope.

None among them are known to have contracted infection, although it is possible that one man employed by Dr. Carpenter on Sesse, in 1911 and 1912, may have done so.

In the aggregate very large numbers of natives have transgressed the regula- tions and hunted or fished in the palpalis belt, and often in the most densely in- fested parts of it.

The epidemic of human trypanoso- miasis raged with undiminished viru- lence on small islands where only trans- mission from man to man by the agency of Glossina can be held accountable for its so rapid spread.

Elsewhere it has been impossible to find any indication in the general behaviour of the disease, and the course of the epidemic, which indicates, or indi- cated to those who studied it at the time, that any other factor entered in. 23. It is, of course, not at all improbable that some of the many hundreds and thousands of natives who have been exposed to being bitten by Glossina palpalis in regions where infection is known to have been, or may have been present, may have contracted infection. But, with the exception of one boy who accompanied Dr. Carpenter, and who undoubtedly was afflicted by trypanosomiasis (but who may have been infected in Busoga), and another, who had outward symptoms but in whom trypanosomes appear never to have been found, no suspicious cases have come to light. We have only the death returns and the admissions to the sleep- ing sickness camps upon which to rely, and these are negative. There have only been two deaths returned as by sleeping sickness from Buganda Province during