PUBLIC RECORD OFFICE
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Reference :-
whiwhi C.O. 885
22 PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO
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by rights to be made to reduce the amount of game. The protection of game in a morsitans area on a main road is an obviously suicidal measure.
The question of sudden epidemics of cattle trypanosomiasis occurring outside recognised fly areas, and not followed by any subsequent cases, must be touched upon. These epidemics can always be traced to the introduction of sick cattle from other parts of the country.
The classic instance of this is, of course, that of Mr. Walshe's herd at Kabilo- muliro. This herd became rapidly and heavily infected during one season, and no further cases have occurred since that time. It must be observed that the heroic measures adopted in this instance, namely, the immediate slaughter of all infected and suspected animals, would completely and permanently check an outbreak of trypanosomiasis introduced by domestic cattle even in the presence of an efficient carrier. If these measures were carried out promptly the district would not become a focus of infection, as the disease would be stamped out before the game had become infected. An infected district, it may be remarked, implies a vertebrate reservoir. This is almost always supplied, not by the domestic cattle themselves, but by the game. Until the game have become infected the slaughter of the sick cattle is an absolutely effective measure in stamping out all kinds of trypanosomiasis. Often the natural death of sick animals in country where the cyclical carrier is seasonal is sufficient to prevent the occurrence of further cases during the next season.
It may, therefore, be said that where there is any machinery for the proper surveillance of cattle in a district trypanosomiasis introduced by domestic stock can be stamped out entirely at its first appearance.
Recommendation 6 is framed to effect this in the case of the brucei group of trypanosomes in the Northern Province.
The conditions of those outbreaks of the Kabilomuliro type are apt to be obscure, the really difficult point being that, granted that they occur at all, it is hard to make out why they do not happen far more frequently.
One was well authenti-
Two cases of this kind were met with in this Province. cated, and the details, which I owe to Mr. Teggart and Mr. Chapman of the Public Works Department, were as follows:-
In April, 1912, eight cows were brought from Miduma, near the Kafu, to the Hoima District; they were bought by an Armenian trader, and herded among his cattle. The herd of Naziloomiun (the Armenian) was clean at that time; it had never been diseased, and there had been no deaths except two from easily explicable causes during the past two or three years. Two of the imported cattle died a week or ten days after arrival. The original herd from which they had been taken subse- quently showed a lot of disease, and many of the cattle died.
From July, 1912, to February, 1913, the Armenian lost 40 head of cattle from a disease recognised as the Miduma disease, and with all the clinical signs of cattle trypanosomiasis. From February, 1913, on there has been no sign of illness in the herd. The trypanosome species in the Miduma herd were T. pecorum and T. vivar. No data exist as to the species present in the Armenian's herd.
At first sight this appears to be a good case of mechanical transmission, but on analysis the evidence is not absolutely conclusive, for the following reasons:-
(1) Accurate evidence regarding the complete absence of a cyclical carrier is
wanting.
(2) A cyclical carrier might have been present in the wet season-April to July-and by the following year (the autumn rains may be apparently neglected as regards fly in this Province) the infected cattle had all died-if the outbreak has not spread to the game so as to form an appreciable reservoir no fresh cases would appear in the following season.
It must be remarked that this type of outbreak may have started a focus, if the carrier is present, even although it does not manifest itself by cases among the domestic cattle for some years.
The co-efficient of infectivity among the fly and game must rise to a certain level before it becomes appreciable.
The
The record case was that of a small herd near Kibona. A man bought a sick beast in 1911, one of a small number brought from near Miduma in that year. heast sickened very shortly after being bought; there were several other cases during the next six months (the number was not accurately remembered), and then no more. The herd was kept near the cultivation plot. This also suggests a mechanical trans- mission outbreak, but the evidence is too meagre to be sure. Mechanical transmission undoubtedly occurs, but it seems to require a somewhat fortuitous concourse of
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circumstances to make it effective, such as recent cases of illness showing good numbers of trypanosomes in the blood of the infected animals, large numbers of biting insects, and closely herded cattle.
In conclusion, I should note that the name T. brucei is used here in the sense of the Royal Society's Commission, 1908, et seq. The recent discovery of the probable error of this name in its present application has not been taken into account, as the whole point awaits further elucidation.
Details of Condition of Glossina morsitans.
As a result of the large amount of experimental data now available in regard to the life-cycles of various trypanosomes, one is justified in concluding that in Uganda fly showing a proboscis infection only are infected with either T. vivax or T. uniforme; fly showing a general infection of both gut and proboscis are infected with either T. nanum or T. pecorum; fly showing an infection in gut and salivary glands are carrying T. gambiense or T. brucei; (T. rhodesiense has this kind of development also); fly showing trypanosomes in the gut only are early, not yet infec- tive, stages of T. nanum or T. pecorum or T. gambiense or T. brucei or T. rhodesi- ense; fly showing Herpetomonads or Crithidia in the gut are not carrying any of the typical mammalian trypanosomes under present consideration. No crithidial or herpetomonal infections were found among the flies examined.
For general statistical purposes in a climate such as that of the Northern Province (ie., where the variation in temperature is exceedingly slight) infected flies may be regarded as infective flies. The space of time during which a fly is infected but not infective may be taken roughly as 30 days (in the proboscis forms consider- ably less; the figure given is a fair working average where several species are involved); the whole life of a tsetse fly comprises upwards of six months. Once a fly is infective it continues to be so until the end of its life; the short period of the development may, therefore, he neglected. The estimate of the infecting power of Glossinide is always underestimated in the handling of figures, as an infective fly is generally reckoned as being the equivalent of one infecting bite. An infective fly probably injects the trypanosome it is carrying into some host ten or fifteen times every month.
There were 445 flies-Glossina morsitans— in the group examined from the fly area on the Masindi-Nakasongola-Kampala Road, between Katugurukwa camp and Kibangya. The bulk of the flies came from a swamp about eight to ten miles from Katugurukwa.
There were 407 males and 38 females in the group. The flies were caught between the 21st July and the 2nd of August. There was a good deal of rain during the period. I have no explanation to offer as to the numerical discrepancy between the sexes.
Out of the total, 445, there were 42 that showed a definite infection with trypanosomes, viz., 9 per cent. of the 42 infected trypanosomes; 17, or 38 per cent. showed trypanosomes in the proboscis only, and implied infection with T. vivax or T. uniforme; 13, or 29 per cent. showed trypanosomes in the gut and proboscis, implying infection with T. pecorum or T. nanum. The trypanosomes from the proboscis of one of these flies were injected into a dog, who showed typical T. pecorum trypanosomes on the 14th day. The remaining 12 flies of the 42 infected, i.e., 2.7 per cent., showed trypanosomes typical of mammalian forms in the gut only-nearer diagnosis is not possible in these cases the proboscis forms, such as T. vivax and T. uniforme, are excluded, but there is nothing to distinguish the other forms. The trypanosomes might belong to the earlier development of T. nanum, T. pecorum, T. brucei, T. gambiense, T. pecaudi, or T. rhodesiense. The probability here is that they belong to T. pecorum or T. nanum.
PART II.
REPORT ON THE PRESENT CONDITION OF THE KAFU RIVER DISTRICT AND OF BURULI IN REGARD TO THE SPREAD OF TRYPANOSOMIASIS. September, 1913, by (Miss) M. ROBERTSON.
The southern part of the Masindi District along the northern bank of the Kafu River presented features of particular interest in regard to the trypanosomiasis of cattle.
The villages from beyond Miduma in the east right along to the Nile are so scattered, and the cultivation patches are so small in relation to the uncultivated land, as to have no geographical significance. The country consists for the most part of flat short grass plains, with borassus palms growing at considerable distances