CO885-(21-23) — Page 573

PUBLIC RECORD OFFICE

Reference :-

C.O. 885

22 PUBLIC RECORD OFFICE, LONDON

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

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glands are punctured, and microscopically examined. A microscopical examination is also made of the blood of all cases showing any rise of temperature.

Since the establishment of this station some 17,000 natives have passed through for work in Southern Rhodesia.

Four cases of trypanosomiasis have been found at this station-three amongst the natives passing through to the south, one from a neighbouring district.

The disease has not been found in any native subsequent to his having passed through this camp.

The duties of the Medical Officer stationed at Fundu include, in addition to the examination of all natives passing through to the south, the general medical work of the district (including vaccination), and the examination of the district and the investigation of the position of the disease.

During December and January the villages on the Fundu-Nyanje road, and within a ten-mile radius round Nyanje, the Nyanje-Petauke, and the Petauke- Kamono roads, were examined by Dr. White. 7,122 people were seen, and one case of trypanosomiasis was found.

The southern part of the valley of the Lukasashi River was examined in November by Dr. Edington. No case of the disease was found.

The Lukasashi Valley from Fundu to the Mlembo Plantation was examined by Dr. F. O. Stohr during May and June of last year; 1,385 people were seen; no case of the disease was found.

During August and September the inhabitants of the area known as the Sitchitambo-Kanduza fly-belt were thoroughly examined by Dr. R. S. White; in 310 instances a microscopic examination was made of either the blood or gland juice, or both, of these people. In no case was the disease found.

No satisfactory explanation can be offered as to the failure of this disease to spread under the seemingly eminently favourable conditions which exist in the greater part of the Luangwa Valley area and elsewhere at similar altitudes, and under which it has been known to exist for at least five years. A large proportion of the game which is plentiful in these areas harbours a trypanosome which is identical morphologically and in all its reactions with the T. rhodesiense; the trans- mitter, Glossina morsitans, is plentiful, and climatic conditions are suitable, not- withstanding which the disease has shown no inclination to spread.

It may, however, be suggested as a possible explanation that-

(1) the disease is an old one and had, in all probability, existed for a con- siderable number of years before it was recognised, and is endemic, and that the bulk of the population is immune;

(2) the source of supply of the infection, namely, the extent to which the game is infected with T. rhodesiense, may not be so extensive as is at present thought;

(3) the tendency of the disease, so far as is at present known, to appear localised, such as in the neighbourhood of the Luangwa, north and south of Hargreaves, and in the proximity of main roads, and. as pointed out by Dr. Ellacombe, in the West Serenje District, rather than to be found equally distributed elsewhere where climatic con- ditions are suitable, and where there are equally favourable conditions as regards the abundance of both transmitter and "reservoir," would suggest that there is still a link wanting in the chain of evidence in favour of the "fly" and game" trypanosome being identical with that which causes human trypanosomiasis.

*

THE RELATIONSHIP OF HUMAN TRYPANOSOMIASIS TO Game.

It was pointed out in the last Sleeping Sickness Report for this Territory (February, 1912), that in connection with the prophylaxis of the disease, game would have to be considered from two practically independent points of view.

The first, as offering a means of subsistence to the carrier of the disease, i.e., the Glossina morsitans.

The second, as reservoirs for the organism causing the disease.

1. The question as to whether game is essential for the maintenance and pro- pagation of the fly is still in exactly the same position as it then was. We are still in ignorance as to what relationship exists, proof is still wanting that any essential relationship does exist.

2. As reservoirs for the organism causing the disease. It has now been accepted by a considerable number of authorities that the trypanosome first found in the blood of a waterbuck at Nawalia in August, 1911, by Dr. Kinghorn, is the

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same organism which causes that variety of human trypanosomiasis met with in Glossina morsitans areas in this Territory. This organism has since then been found by Dr. Kinghorn and the other members of the Luangwa Sleeping Sickness Com- mission to be widely distributed amongst the fauna of this country, and it has also been shown that its carrier is the Glossina morsitans. The final proof of its identity, i.e., its pathogenicity to human beings is, however, still wanting.

The identity of this trypanosome is questioned by Dr. Taute, of the German East Africa Sleeping Sickness Commission, who has recently performed the bold experiment of injecting himself and a series of experimental animals as controls with blood from a naturally infected dog, and of allowing himself to be bitten by flies known to be infected with it.

In the former case, all the seven animals used as controls became infected and died.

In the latter experiments, also, the control animals became infected and died, whilst the author remained healthy, and has since proved by the inoculation of susceptible animals with his own blood that he did not become infected.

There is, therefore, some doubt thrown on the identity of the T. rhodesiense and

the organism found so widely distributed in game, and hence on the part which the antelope plays as the reservoir of sleeping sickness..

The contention in favour of the non-identity of these trypanosomes is also supported by the conditions found in association with a heavy infection of the game with this trypanosome, and its failure, under suitable conditions, to spread to human beings; these circumstances have been reported elsewhere.

The complete proof of the identity of this trypanosome needs a series of experi inents such as that carried on by Dr. Taute. No more than an inference as to identity can be drawn from the facts at present available.

It can, however, be claimed that if the organism be the T. rhodesiense, then the possibility of immunity amongst man is an established fact, and one having a most valuable bearing both on the future of the disease and the alleged necessity for drastic preventive measures, such as the wholesale destruction of game.

THE EXPERIMENTAL DETERMINATION OF THE RELATIONSHIP WHICH EXISTS BETWEEN GAME AND FLY, AND INCIDENTALLY BETWEEN GAME AND HUMAN TRYPANOSOMIASIS.

With the object of determining these points, it was proposed that an experiment (ride report for 1912, page 25), should be undertaken, which was to include the complete destruction or removal of all game in the supposed limited and definitely restricted fly belt in the neighbourhood of Sitchitambo's and Kanduza's Villages, on the southern border road, from which it was expected definite conclusions could be drawn as to what effect such destruction had on the life of the fly.

This experiment has not been carried out. It was found on more careful exami- nation (made by Dr. R. S. White in September, 1912) that this fly-helt, formerly thought to be definitely restricted to the area named, was not so restricted, but extended on the west to the banks of the Luangwa River, and there became continuous with the fly-belt running north and south along this river. And on the east and south extended into Portuguese territory. It was also found that game in this area was extremely scarce, and consequently its destruction could not be expected to yield the required information. It was, therefore, decided that this was not a suitable site for the proposed experiment.

The Lukasashi Valley, north of the Nkushi-Petauke Road, was next examined (by Mr. LI. Lloyd, October and November, 1912), with a similar object in view; it was found to be in every respect eminently suitable. The following is an extract from Mr. Lloyd's reports :-

From these data it will be seen that tsetse fly exist practically through- out the valley of the Lukasashi in the part examined, including part of the Kaombi Stream and the Manda as far as the hills.

"Game is moderately numerous throughout the district. The Fauna is that of the Luangwa Valley rather than that of the Plateau.

L.

The secluded position of the valley, and its dry condition during the winter, render it a specially suitable place for the proposed experiment." An experiment of this nature and magnitude requires careful consideration in all its aspects before being attempted, i.e., (1) its cost; (2) the probable result; (3) the possibility of arriving at a correct conclusion as to the interpretation of the result.

I. Its cost. The following rough estimate is submitted; it is based on the assumption that the area experimented on should not be less than approximately 400