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Studies on the epidemiology of sleeping sickness in East Africa V. Sleeping sickness in the Bunyoro District of Uganda
585 TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE. Vol. 54. No. 6. November, 1960.
S T U D I E S ON T H E E P I D E M I O L O G Y OF S L E E P I N G S I C K N E S S IN EAST AFRICA V.
SLEEPINGSICKNESS IN THE BUNYORODISTRICT OF UGANDA BY
K. R. S. MORRIS, D.SC.* East African Trypanosomiasis Research Organization The Bunyoro District of Western Uganda is bounded by Lake Albert on the west, by the Victoria Nile to the north and east and by the prosperous Mengo, or Buganda District in the south. Lake Albert and the Nile have, for a very long time, served as important routes for canoe traffic. Immediately north-west of Bunyoro lies the West Nile District, at one time the Lado Enclave of the Sudan, with a very primitive population. Large numbers of these people, from 25,000 to 30,000 annually in recent years, pass through Bunyoro to work in the rich coffee, sugar and cotton growing areas of Buganda and Busoga. Both the West Nile and the Busoga Districts have been the scene of severe epidemics of sleeping sickness in the past 30 years. Thus, although Bunyoro, at the beginning of this century, suffered from a sharp epidemic which was brought quite soon under effective control, it has never been entirely free from trypanosomiasis since then, a penalty for its geographical position. Some interesting features in the epidemiology of sleeping sickness can be learned from a study of this District. FIRST APPEARANCE, AND THE EPIDEMIC OF 1904-1914 The first recorded appearance of sleeping sickness in Bunyoro was the case, admitted to Entebbe Hospital in August, 1904, of a Swahili sailor working on the Butiaba-Wadelai steamer. He had been 2 years on this service, which led to the suspicion that his infection had been acquired locally, and, with the alarm of the Lake Victoria epidemic then at its height, gave rise to an immediate search for cases in Bunyoro, particularly along the rivers Victoria and Albert Nile. The Medical Officer at Hoima, Dr. Pooley, collected 18 cases from the Bugungu area in north-west Bunyoro, from " Mwanga's shamba," lying in the angle between the Weiga River and its tributary the Izolya, draining into Lake Albert 20 miles south of the Nile. Dr. Greig, in a search in the villages situated on the Victoria and Albert Niles from the Murchison Falls to Nimule, found four cases between Fajao and Kimori (7 miles from the mouth of the Victoria Nile), one at Wadelai, and one from Duffle in the then Lado Enclave, now the West Nile District (GREIG, 1905). * It is a pleasure to acknowledge the help given by the Uganda Medical Department and Tsetse Control Department during this investigation, and in particular the most valuable co-operation of Dr. G. Timmis, then D.M.O. Bunyoro, in the difficult task of tracing information on the spot.
586
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Map of Uganda to show the track of the epidemic. All place-names in the text are shown. Investigation of the Bugungu area by ADAMS (1907), in the following year, 1905, showed that a fairly severe epidemic was already well established on the lower Weiga River, with at least 200 deaths attributable to sleeping sickness during the past few months. Infection was with Trypanosoma gambiense, and the vector, Glossina palpalis, was observed to be abundant on the Weiga and Izolya rivers. T h e epidemic was found to be localized in a group of about a dozen villages situated on and between these two rivers, with the location of Dr. Pooley's original 18 cases, Mwanga's shamba, right in their midst. Mortality was, in many places, severe, as can be seen from Dr. Adams's list of villages where infections were found :
On Weiga River. Kitagania Kiriangandwa Kiperi Kiewata Mkondo Salizi Kibamezi Buseswa Kinyambezu Kakora
On Izolya River. 6 of 12 died 12 of 30 died 12 of 25 died All dead Evacuated 50 of 60 died 5 of 20 died 25 of 40 died 8 of 60 died 5 of 100 died
Baramweli Mutumbwa Kitchwanti
7 deaths past 3 months 5 deaths past 3 months 5 deaths past 3 months
M a n y of these villages can be seen on an Ordnance Survey map compiled in 1905 (KXNG, 1912), which shows clearly the distribution of what must have been an extensive population living, at that date, in this north-western quarter of Bunyoro and along the
K. R. S. MORRIS
587
valley of the Albert Nile as far as the Sudan frontier. Only two of the villages mentioned by Dr. Adams, Kakora and Mutumbwa, can be traced today. No more cases were found on the Victoria Nile but an advanced case was seen at Koba, in the corner of Acholi between the Victoria and Albert Niles (HoboES, 1907), the scene of a severe outbreak 4 years later. Although the progress of the epidemic on the Albert Nile can be followed (MORRIS, in press), detailed reports for Bunyoro are missing for the next few years, but the development of a more extensive and quite severe epidemic in this District can be seen from records summarized in the Uganda Medical Department's Annual Reports, which give the numbers of deaths from sleeping sickness in Bunyoro for the next 15 years as follows : 1906 1907 1908 1909 1910 1911 1912 1913
369 deaths 170 ,, 461 ,, 254 ,, 277 ,, 168 ,, 84 ,, 41 ,,
1914 15 deaths 1915 11 ,, 1916 7 ,, 1917 8 ,, 1918 5 ,, 1919 5 ,, 1920 2 ,,
Confirmation of these figures and information on the extent of the epidemic, which involved the greater part of the Weiga River system as far east as Kikoroto and both banks of the Victoria Nile, was obtained in histories gathered during the present investigation from a number of older inhabitants who were interviewed in places as widely separated as Atura, Bulisa and Wansiki in Bugungu, Masindi and Hoima. The recorded figures will represent only a proportion of the incidence in the district during this period. The infected areas were difficult of access, and only a few medical and health staff could be spared for this district from the far more disastrous Lake Victoria epidemic. For example, there are no records of the course of the epidemic along the shores of Lake Albert, but a lively and intelligent old man, Ezekeya Bwamgiregu, living at Kibiro, a salt-working village 12 miles S.S.W. of Butiaba, gave a most coherent and lucid history, much of which was confirmed independently by the Saza Chief of Masindi. At the beginning of the century the shores of Lake Albert held a very big population, not only in the larger villages which still exist today, but almost continuously in between, engaged in fishing and salt production, trading mainly with the Congo. Sleeping sickness came in from the north, from Bugungu, at a date which could only be given vaguely, 1906-12, and spread rapidly southward along the lake shore, from village to village, finally reaching the head of the lake in Mubende District. Mortality was heavy. Butiaba lost more than half its population ; Kibiro was reduced from over 1,000 people to 250. In the smaller settlements and camps most of the people died. There was a general movement away from the infected places and most of these people settled above the escarpment, and returned to the five or six main fishing ports only after 10-15 years. The Kibiro informant gave a clear and unmistakable description of the symptoms of sleeping sickness in his account, and quoted the local name for the disease, " okuhungira " meaning " nodding." The table given above shows also the effect, in checking the Bunyoro epidemic, of the measure of removing the population from the shores of Lake Albert and banks of the Victoria and Albert Niles, which was decided upon in 1908, and put into operation in 1909 and 1910 (Uganda, 1909, 1910). Although this measure brought what might have been a much larger epidemic under control, with a striking and progressive reduction in the number of deaths from 1912 onwards, yet the area over which it was applied was undoubtedly excessive, G
588
SLEEPING SICKNESS IN BUNYORO DISTRICT, UGANI~tA
and has caused the subsequent loss of enormous tracts of country to the game tsetse. For example, there were no G. palpalis along the 7 miles of Victoria Nile flanking the delta into Lake Albert, or along the lake shore as far as the river Weiga. The people assert that there was no sleeping sickness there, either. Yet all the population of this richly productive sector of Bugungu was removed. The value of this area for both cattle and fishing was remarked upon by BAKEa (1869) in his journey in 1866, and is remembered by the older inhabitants today. Fishing is recovering, with an extremely prosperous port with 300 canoes at Wansiki, right on the delta, and there were some herds of cattle. But the vast belt of G. morsitans and G. pallidipes which now stretches right across northern Bunyoro is a direct result of the drastic removal of the people in 1910. The country along the Victoria Nile, from Atura to its mouth, was continuously populated and well cultivated up to that time (Map given by King, 1912). There are two possible routes whereby the infection giving rise to this early epidemic could have entered Bunyoro. It could have come gradually eastward from the Congo and have been present for some time as an undetected endemic on the Albert Nile, or it could have been carried rapidly north-westward from the Lake Victoria epidemic after its start around 1896, by Baganda and Banyoro traders who used to move freely to and from Bunyoro at that time. The former theory, of direct introduction from the Congo, has the more convincing evidence in its favour. The facility with which T. gambiense can be introduced by mass movements of people coming from or through infested areas has been shown in the Acholi-Lango studies and by work in West Africa (MoaaIs, 1951, 1959). In 1887 Stanley, with 500-800 followers, arrived on the G. palpalis infested western shores of Lake Albert after having passed during the previous months through long reaches of the Congo heavily infected with sleeping sickness. STANLEY(1890) records that many of his porters were very sick on their arrival at Lake Albert. It is almost inconceivable that this movement could not have introduced some infections and established them in the country west of Lake Albert at this time, also on the Albert Nile as far as Wadelai, reached by one contingent of Stanley's expedition in their relief of Emin Pasha. Emin Pasha's disbanded army and their camp followers subsequently settled at one of Stanley's old camps, Kavali's, just west of Lake Albert, before they were brought by Lugard and settled in Buganda and Busoga between 1891 and 1895. The timing of this movement, of 7,000-8,000 people, fits adequately with the start of the Busoga outbreak on Lake Victoria in 1896, assuming that some of Emin Pasha's rabble brought infection with them from the neighbourhood of Lake Albert. When the earliest evidence from Bunyoro is examined the timing is also correct for a direct introduction here from the Congo. When, in 1905, Dr. Densham investigated closely into the earliest occurrences of sleeping sickness on the Albert Nile, near Wadelai, Emin Pasha's former headquarters, he met with several advanced cases which might have been infected for 4-5 years ; he found a village, Ajei's, which had already been wiped out by sleeping sickness with little trace left, indicating a long duration of the disease here ; and he found that a large proportion of his cases were coming from the Congo. The inhabitants stated that sleeping sickness had been known previously at Logwarri, on the Kiboli River, in the Lubari Province of the north-eastern Congo, and had been introduced from there (HoDQES, 1909). Here is a continuous sequence of records of the disease on the Nile and its neighbourhood just north of Bunyoro up to the date of the infected Swahili sailor and the first batch of Bunyoro cases in 1904. Thus, of the two theories the simplest, and to me the most acceptable, is that when the Bugungu outbreaks were discovered in 1905 the disease
K, R. S. MORRIS
589
had already been present here and on the Victoria and Albert Niles for a number of years undetected, having arrived here directly from the neighbouring loci in the Congo. The longer route, back from Lake Victoria by the medium of southern Mengo and Busoga traders after infection had reached their country from the Congo, involves more speculation and has less evidence for its support. RESETTLEMENTOF THE LAKEALBERTSHORES, 1920 The period of low and steadily decreasing incidence, from 1916 to 1920, led to a move for resettling the vahable lake shore land which had been evacuated in 1909. In 1920 Dr. Hale Carpenter found only one case when he examined 650 people, formerly from Bugungu, settled in the Waki River area, so the whole of the Bugungu coast was opened for fishing and that stretch north of the Weiga River made available for inhabitation. South of Butiaba and Kibero, which had never been evacuated, the ports of Kaiso, Tonya and Buhuka were re-opened. Resettlement in these areas continued during the next 3 years, with annual inspection of the inhabitants, who were found completely free of infection, with the exception of two or three long-standing cases in persons who had returned with the infection in them from the Waki River close to Butiaba. Bugungn had over 1,000 settlers by 1925, but the interior, along the Victoria Nile and Weiga River and its tributaries, was never opened because of the heavy G. palpalis concentrations along these rivers. This land now constitutes the southern half of the Murchison Falls National Park. PERIOD OF INTRODUCTIONS, 1940-55 There is an almost complete blank, which the present investigation was unable to bridge, in the information from Bunyoro from 1925 to 1940. No records of trypanosomiasis cases can be found anywhere. The recording of data for this, as for several other districts, is often so haphazard that the absence of recorded cases cannot be given factual interpretation, one cannot even be sure that it means that no outbreaks occurred. In all probability it does mean that the disease was rare, trypanosomiasis was still causing grave concern in the country to the north and we know that the annual inspection of the inhabitants of the fishing ports from Butiaba southward was still kept up. In the few years for which information is available, 1937, 1939 and 1940, no cases were found on these inspections. From 1941 to the time of writing a fairly continuous, though not necessarily complete, series of records has been obtained. As will be explained below, the disease during this period was being introduced from the epidemic sources outside Bunyoro by the stream of migrant labourers passing through the District. Up t o 1940 the main source was of T. gambiense from the West Nile and Acholi Districts to the north. But in 1941 T. rhodesiense appeared in sudden epidemic form in the Busoga and Mengo Districts to the south, introducing a second potential source with a different pathogenic agent (MAcKIcHAN, 1944). The question now arises of assigning the cases between 1941 and 1955 to one or other of these trypanosomes, and diagnosis between them is still a matter of great difficulty and not entirely free from controversy among the experts. Diagnosis in the local hospital or dispensary can rarely supply the answer, even the laboratory method of 10 years ago, of deciding by the presence or absence of post-nuclear forms, is no longer accepted. For example, in an outbreak centred on Kikora, which will be described below, rats inoculated from four patients from the same village and found infected at the same time, received the laboratory d i a g n o s i s - two T. rhodesiense, two T. gamln'ense. Not only was it extremely improbable for one locality to be
590
SLEEPING SICKNESS IN B U N Y O R O
DISTRICT~ U G A N D A
suffering from a mixed epidemic of these two trypanosomes, but T. gambiense could be definitely ruled out by the absence, proved by extensive search, of its vector, G. palpalis, everywhere in the neighbourhood. The Bunyoro cases during this period of introductions are, therefore, differentiated on epidemiological grounds, to two series which are called T. gambiense, occurring in two main periods, 1941-44 and 1953-57, along the Victoria Nile and Lake Albert shore, where the vector G. palpalis was present ; and to two groups of T. rhodesiense, in 1942 and 1948-50, either among the labourers returning from the Busoga area infected with the species or in the villagers of a locality just off the main route, where G. morsitans and G. pallidipes, both known vectors, were in close contact with the infected villages. 1)
T. gambiense from the North
In 1941 four cases were reported, two coming from lake-shore villages south of Butiaba, one found among the Butiaba railway staff, and a woman just arrived from the West Nile who was found infected in Masindi. There was no doubt that she had brought the infection with her from the West Nile District. At that time this District was just recovering from its second severe and wide-spread epidemic of T. gambiense. In 1942 a fisherman from the village of Kijumbura, on the Victoria Nile 20 miles south of Atura Ferry, was found infected, and a year later three more cases were reported from this village and one from Mutunda, on the Bunyoro side of the ferry. In 1944, 20 cases were treated from this area. It is extraordinary that no details could be found in the files or reports of any kind of what must have been quite a heavy epidemic. Even the following year, 1945, had no cases recorded from Bunyoro although it is difficult to believe that T. gambiense infections would have died out so completely. It is likely that some of the 12 cases reported from " Other Districts " in the Medical Department's Annual Report for 1945 may have originated here. The story of this epidemic was only obtained by seeking out information on the spot. The main information came from a venerable ex-chief, Zakalija Mwanza, and from the Assistant at Mutundu Dispensary, Philip Okello ; but a number of other interviews were made from which the following picture was built up. The outbreak was centred on the village of Kijumbura, situated close to the Victoria Nile from which the inhabitants obtained their water, coming into close daily contact with G. palpalis in doing so. There was a ferry across the Nile to Lango District, but this was abandoned after the outbreak. The onset corresponded with the first recorded case, in 1942, when people from Kijumbura started dying, and continued to do so for the next two years. In 1944 at least 50 deaths occurred, a high figure considering that no notice of such a calamity could be found in official records, but on which very close agreement was found between the various sources of information consuited on the spot. The majority of the inhabitants of Kijumbura were said to have died of sleeping sickness, and a smaller number of deaths occurred in surrounding villages. The survivors left for the villages of Panyadwoli and Koki further north, towards Mutunda, where they are living today, and some, originally Langos, returned to their own country. Apparently the sickness, which was well described by the people, died out as soon as they had moved from the infected area. In fact this is unlikely to have happened in sleeping sickness due to T. gambiense, whose development in the patient may take 2 to 3 years, more probably it was just not reported, as the very meagre documentation of the 1944 outbreak would indicate. Confirmation of the more prolonged and extended nature of this epidemic has just been obtained by the D.M.O. Bunyoro, Dr. Timmis, after talking to an ex-chief of Koki, by name Oyuru. Oyuru confirmed the heavy deaths around Kijumbura, which
K. R. S. MORRIS
591
included three chiefs whom he named, and stated that the sickness then spread northwards as far as his village of Koki, where further deaths occurred, with the epidemic lasting till 1945. The names of people sent from Koki to Masindi Hospital were given. Occasional cases continue to be brought in from north-eastern Bunyoro, from the Nile or the Tiff River near Kirandongo, with several coming from the adjoining Maruzi and Oyam counties of Lango. In 1953 there were five cases from villages near the Nile and one from Lango, in 1954 there were two from Mutunda area and three from Lango, and in 1955 a single case from near Kiryandongo. That is the last reported case of trypanosomiasis in Bunyoro. The appearance of T. gambiense in this district in 1941 was almost certainly due to its introduction from the heavily infected West Nile District. Some 4,000 cases had been treated there during the previous 6 years, with 373 and 304 new infections occurring in 1940 and 1941. Seven thousand labourers from West Nile and over 5,500 from the Congo and Sudan passed through Bunyoro in that year to work in Mengo and Busoga, and this number would be bound to include some undetected T. gambiense cases, which would have every chance of passing on an infection, either at some point on the Lake Albert shores or at one of the Victoria Nile ferries. There are the known cases of the infected woman from the West Nile, diagnosed on reaching Masindi in 1941, and of an Asian from Butiaba who was found to be infected on his return from Pakwach a few years later. It is much less likely that the more recent infections, of 1953-55, were introduced in this way, the West Nile trypanosomiasis incidence was below 10 cases per year then, and in Lango and Acholi equally low. It is much more likely that trypanosomiasis never disappeared from N.E. Bunyoro, smouldering on at a low incidence in villages on both sides of the Nile here. Two of the cases in 1953 came from Alero, a small village 5 miles off the main road N. of Mutunda, right on the banks of the Nile with G. palpalis infested water supplies occurring within 100200 yards of many of the houses. There was regular communication across the river with Lango. The northern end of the village is almost opposite Kamdini, where a fisherman was found infected in October, 1957, and where Dr. Snell records a case, certainly infected locally, in 1950. G. palpalis is present all along this part of the Nile from Atura to Kamdini Falls, where it is abundant. There are many Lango and Acholi settlers among the villages on the Bunyoro side of the river, and, apart from the occupation of fishing, there is a constant traffic across the Nile between the people on both banks. The river may represent a political boundary ; both biologically and in the life of the people it is a single, natural unit. As such it constitutes the centre of the trypanosomiasis problems in this locality, which can be correctly assessed only with this fact in mind. T. rhodesiense from the South The position of Bunyoro, traversed by much frequented labour routes coming from an infected area to the north, with the consequent introductions of infections of T. gambiense, had made the Medical Officers alive to this danger. When the T. rhodesiense epidemic in Southern Busoga developed in 1941, with its original focus on the Kakira Sugar Estate near Jinja which employed much of this labour, a new threat developed to Bunyoro, this time from the south. Consequently inspection posts were established on the main points of entry of labourers returning from Busoga and Mengo, so that they could be examined for trypanosomiasis. This action was amply justified. An extensive, heavily infested belt of G. morsitans, 12-15 miles in width, existed at that time between the Kafu River and Victoria Nile at Masindi, 2)
592
SLEEPING SICKNESSIN BUNYORODISTRICT, UGANDA
and was traversed by these labour routes, which also came in contact with one or more of the much less extensive pockets of G. pallidipes. In 1943 three West Nile labourers, returning direct from the sugar estates, were found to be infected on examination at Masindi Port. The infection was undoubtedly T. rhodesiense, and because of the foresight of the Medical Department, no local outbreak developed. In 1948, however, a Muganda from Nabiswera, who had recently been working in Busoga and Bukedi, was picked up at the Kibangya post with T. rhodesiense infection. Later the same year three cases with the same infection were discovered at Kikora, a bush village 10 miles south-west of Kibangya, surrounded by heavy G. morsitans belt and flanked by a patch of G. pallidipes. Vigorous search of the area from Kijunjubwa to Kibangya made it possible to detect and stamp on at once a small outbreak of 10 cases in 1949, centred around Kikora. Only two cases were found in 1950. after which no more occurred. There is no doubt that these cases were all T. rhodesiense infections. A suspicion that some might be due to T. gambiense led to a thorough search for G. palpalis, particularly on the Kafu River, by Mr. Bernacca of the Tsetse Control Department, but none was found nearer than its junction with the Victoria Nile. At the same time the D.M.O. for Mengo reported two more cases in 1949 from Nabiswera and a village close by, making a total of three from this locality in 6 months, at least one in an old woman who had never been away from her home. Nabiswera, 17 miles from Kibangya, was at that time closely flanked by belts of G. pallidipes and G. morsitans, and these occurrences, which were found not on a search for trypanosomiasis but on the patient coming with " fever " to the local dispensary, make it clear that T. rhodesiense was being actively transmitted on both the Mengo and Bunyoro sides of the Kafu River at that time. It was most fortunate, and perhaps saved a more serious outbreak, that the Tsetse Control Department's operations for the control of G. pallidipes and G. morsitans by hunting had reached the Nabiswera area by 1949 and was extended into south-eastern Bunyoro in 1951. By 1954 both these species of tsetse had been eradicated from the country from Kijunjubwa to Masindi Port and the danger of further T. rhodesiense introductions by the migrant labour passing this area no longer exists. The course of events during this period of introduction, leading to small, local outbreaks of short duration, can be more easily followed in the following simple table, in which all the records obtained from the Medical Department's reports and files have been set out to show the locality of the infection or at least the place where diagnosis was made. SUMMARY AND CONCLUSIONS
A review of the events just described makes it possible to give an appraisal of the position in Bunyoro regarding trypanosomiasis today, and assess any probable dangers that exist or might arise. The first records of sleeping sickness in Bunyoro District are in 1904, when the diagnosis of an infection in a sailor on the Butiaba-Wadelai steamer led to the discovery of a score of cases in Bugungu area, lying in the angle between the north-eastern shore of Lake Albert and the Victoria Nile. G. palpalis was widespread, and infection must have been with T.
gambiense. In 1905 it was found that quite a severe epidemic was established in Bugungu, centred on a section of the Weiga River, 20 miles south of the Nile, where it was closely populated and heavily infested with G. palpalis. At least 200 deaths from trypanosomiasis had occurred in recent months.
K. R. S. MORRIS
Year
Locality of infection or diagnosis
593
Bunyoro Total G = T. gambiense R h = T. rhodesiense
1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957
3 Lake Albert fishing ports. 1 woman ex W. Nile 3 labourers ex Busoga diagnosed Masindi Port 1 Kijumbura fisherman 3 Kijumbura, 1 Mutunda 20 Kijumbura & area. 1 Masindi Port, 1 Bisso near Butiaba No records, but probably cases present, viz. 12 in Med. Ann. Report under " Other Districts " No records Inspection Lake villages showed no cases 1 Butiaba who had contact with West Nile 1 Kiryandongo 3 Kikora. 1 Baganda from Nabiswera 10 Kikora-Kibangya area on Kafu River (2 cases Nabiswera recorded M.O. Mengo) 2 Kikora area 1 case Kamdini (Lango) No records No records 2 Alero. 1 Mutunda. 2 S.W. of Mutunda. 1 Akokoro (Lango) 3 ex Maruzi (Lango) diagnosed Masindi Port. 1 Mutunda. 1 Kiryandongo 1 S.W. Mutunda 1 case Kamdini (Lango)
4G 3 Rh 1G 4G 22 G
2G 4 Rh 10 Rh 2 Rh
1G
6G 5G 1G 0 1G
During the next 5 years a much wider epidemic developed throughout the greater part of the Weiga River, and along both banks of the Victoria Nile, which was well populated for most of its length at that time. F r o m 200 to 460 deaths a year were reported between 1906 and 1910. F r o m this north-western Bunyoro outbreak the infection spread southwards along the shores of Lake Albert and decimated the fishing population which formed an almost continuous line of settlement from Butiaba to the southern end of the Lake. T h e epidemic was dealt with by the removal of the populations of Bugungu, the Victoria Nile, and the Lake Albert shores, in 1909-10. This had a rapid effect in reducing the n u m b e r of cases, until, in the five years 1916-20, an average of only 5.2 deaths per year were recorded from Bunyoro. Investigations by the early workers and the local evidence they obtained indicate that sleeping sickness had been in existence on the Albert Nile for a good many years before 1904, from its source in Lake Albert to Wadelai, the headquarters of Emin Pasha, and that its earliest introduction was probably from the eastern Congo. By 1920 the comparative freedom of this district from any infections led to the resettlement of Western Bugungu and of the lake shores south of Butiaba, but an immense stretch of northern Bunyoro was left uninhabited, and at present contains only game, G. morsitans and G. pallidipes. Most of this area now lies within the Murchison Falls National Park. Data for the period 1925-1940 are almost completely lacking. It is unlikely that any major outbreaks occurred, but beyond that it is impossible to say, as records from 1941 show
~94
SLEEPING SICKNESS IN BUNYORO DISTRICTp UGANDA
clearly the introduction of cases by labourers from West Nile, which had then had a severe epidemic for 6 years. In 1944 a small epidemic of T. gambieme infection broke out on the Victoria Nile 20 miles south of Atura Ferry, in which 20 cases were diagnosed and treated, but at least 50 deaths had already occurred. The outbreak was centred on one small village, Kijumbura, close to the Nile, where there was intimate contact between the people and G. palpalis, and it ended abruptly after most of the inhabitants had died and the rest had moved away. It is probable that T. gambiense has remained in very low endemic form, often unnoticed, on this section of the Nile, where there are a number of villages in close contact with G. palpalis and where, taking both Lango and Bunyoro banks as the epidemiological unit, trypanosomiasis has hardly been absent during the past 15 years. There were six and five cases in 1953 and 1954 respectively, one in 1955, and one from Lango in 1957, occurring right opposite the location of two of the 1953 cases. A threat of introduction of trypanosomiasis from the south came with the T. rhodesiense outbreak of 1940 in Busoga, but the foresight of the Medical Department in examining northward-returning labour at the main points of entry into Bunyoro averted this danger until 1949, when a small outbreak of 10 cases of this infection occurred at Kikora, just south of the point where the Kampala-Masindi road, used by much of this labour, crosses the Kafu River. G. raorsitans and G. pallidipes occupied a wide zone of country on each side of this river, but there was no G. palpalis. Three T. rhodesieme cases were found at Nabis, wera in Mengo at the same time, and there is no doubt that this infection was endemic on both sides of the Kafu River at that time. The elimination of both species of testse from the whole of this area by 1954 means that this danger no longer exists. An examination of these early events in the light of the knowledge of epidemiology possessed today proves instructive. The only big epidemic in Bunyoro, that of 1904-14, did not originate on either of the Nile Rivers or on the shore of Lake Albert, which offered possible sites with a human population and G. palpalis in contact, but on a part of the much smaller Weiga and Izolya rivers where many villages were clustered about a stretch of river infested with G. palpalis in narrow riverine habitat, a situation which has already become familiar, in Busongora, Acholi and Lango in Uganda, and in Nyanza Province in Kenya. Under the favourable conditions of close and repeated man-fly contact in this early focus the epidemic rapidly developed, as the number of recorded deaths show, and spread throughout the places where there was a fairly high human population in contact with G. palpalis, that is up the Weiga and its tributaries, along the Victoria and Albert Niles, and along the shores of Lake Albert. The removal of the populations from these danger zones has changed the whole picture since then. Along the Nile from Kamdini to Fajao and throughout practically the whole of the Weiga River system, which lies in the National Park, there are no inhabitants, and, except for the 15 miles of Bugungu coast where there is no G. palpalis, the population along Lake Albert is greatly reduced in numbers and confined to a few widely spaced and comparatively small villages. The effect of depopulation on tsetse was to cause an immense increase in the numbers and distribution of the game-feeding species, G. morsitans and G. pallidipes which now occupy vast tracts of the country that held thriving populations with their cattle up to 50 years ago. The distribution of G. palpalis remains substantially the same. This species occurs all along the Victoria Nile from Lake Kyoga to 6 or 7 miles below the Paraa Ferry, with a rather broken distribution associated with the presence of riverine forest or evergreen fringing
K, R. S. MORRIS
595
thicket. It is absent from the lowest 7 miles of the Nile and from the shores of Lake Albert from this point to south of Butiaba, but abundant on all the rivers flowing into this section of the Lake, from the Weiga to the Waki. South of Kibero G. palpalis is present almost continuously in the evergreen lakeshore vegetation. It seems to be entirely absent from the Kafu River. During the present investigation this species was caught with ease and in numbers indicating permanent fly communities on the Nile north of Atura Ferry and at the Paraa Ferry, and troublesome swarms were met with from here to the Murchison Falls. G. palpalis was encountered again in numbers south of Kibero, and was a pest to passing canoes and in fishing camps. This species represents a danger, however, only when it is in close contact with a fairly dense and extensive human population, such as that which existed before the epidemic on the Weiga and along the Lake Albert shores. The welt populated parts occur today only around the few more important centres, such as Masindi and Hoima, from which extensions of fairly well populated land stretch out along the main roads. These populations are not in close contact with G. palpalis with the exception of those from Masindi Port to north of Atura Ferry and the lake-shore fishing villages south of Butiaba. In both these areas the population is small and discontinuous, i.e. is not of the pattern which experience elsewhere shows to be associated with the development of outbreaks of T. gambieme. It is possible to say, then, that since the time of the first epidemic the intrinsic danger from T. gambieme in Bunyoro has become greatly reduced. The main danger is now extrinsic. There are still populations, although small, in contact with G. palpalis. Outbreaks of this trypanosome did occur in an adjoining District from which came much frequented labour routes, making its introduction almost a certainty. Under these conditions what have been described as "secondary" or " peripheral " areas of infection (Moams, 1951) can, and did develop in Bunyoro, dependent on the introduction of infections from the true endemic foci outside. With the great extension of G. morsitans and G. pallidipes, a potential danger from T. rhodesiense also arose, which became real with the onset of the Busoga epidemic, at the other end of the labour route, in 1940. Although this danger has been offset by tsetse control in south-east Bunyoro it still exists in many other parts of the District, the game tsetse are still uncomfortably close to Masindi and come almost right up to Butiaba, where thousands of labourers returning from Busoga are embarked. The recent diagnosis of a case of T. rhodesiense infection from Pakwach, in a labourer who had just returned from Busoga and must have passed through Bunyoro, demonstrates the reality of this risk. It seems as if in recent years conditions have become more suitable for the establishment of endemic T. gambiense infection along parts of the Nile, from its exit from Lake Kyoga to Kamdini Falls. The population there is closely associated with the river and is evidently on the increase. But, as has already been pointed out in the description of this area, the Nile is a natural biological unit and a centre for human activities, and not a boundary. It is this fact which counts in the epidemiology of trypanosomiasis, not District limits. It was shown how, in 1949, the T. rhodesiense outbreak concerned Mengo as well as Bunyoro. Similarly the Nile endemic of T. gambiense at the present time involves parts of the Districts of Acholi and Lango as well as Bunyoro. Practical advice on this situation need be neither profound nor prolonged. The danger spots today are : (i) Intrinsically, the Nile from Lake Kyoga to Kamdini, to which should be added the Titi River near Kiryandongo.
596
SLEEPING SICKNESS IN BUNYORO DISTRICT~ UGANDA
(ii) Extrinsically, the above areas are also concerned, and possibly the lake-shore villages south of Butiaba, in the event of a West Nile outbreak developing or the Aswa River epidemic extending ; and, in view of the amount of T. rhodesiense still in Bukedi and Busoga the population fringing the northern and western G. morsitans and G. pallidipes belts should be watched. The more important fringes are along the Masindi-Atura road, the area between Bisso and Butiaba, and the eastern and southern fringes of occupied Bugungu. Insurance against the intrinsic danger can be most readily effected by making a survey, on both Lango and Bunyoro sides of the Nile, of villages within say 5 miles of the river in Maruzi and Oyam counties in Lango and Kibanda county in Bunyoro. To use a single joint organization would be the economical way to effect this survey. The need for control measures, and their formulation, if needed, can be based on the factual data thus obtained. It is almost trite to say that an effective attack on the sources of infection themselves, in West Nile, Lango and Busoga-Bukedi, deals at once with those problem spots and removes the extrinsic dangers not only to Bunyoro but to the several other parts of Uganda where the introduction of trypanosomiasis could occur. Even if this advice be considered as involving much trouble and expense it must be remembered that the task of controlling migrant labour and traders is itself a great trouble and is often almost impossible or extremely cumbersome to enforce. It must also be borne in mind that the stream of labourers passing through Bunyoro in both directions now numbers from 25,000 to 28,000 per year, the numbers have trebled in the past 15 years. The past history of sleeping sickness in East and in West Africa is full of instances in which big developments or increases in movement and ease of transport have brought about fresh outbreaks of this disease. REFERENCES
ADAMS,E. B. (1907). Rept. Sleep. Sickn. Comm. Roy. Soc., 8, 100. BAKER,S. W. (1869). The Albert Nyanza. London. Gm~IG, E. D. W. (1905). Rept. Sleep. Sickn. Comm. Roy. Soc., 6. 273. HODGES,A. D. P. (1907). Ibid., 8, 86. - (1908). Ibid., 9, 3. KING, H. H. (1912). Bull. ent. Res., 3, 92. MAcKIcHAZ~, I. W. (1944). Trans. R. Soc. trop. Med. Hyg., 38, 49. MORRIS, K. R. S. (1951). Bull. ent. Res., 42, 427. (1959). Trans. R. Soc. trop. Med. Hyg., 53, 384. in press. The West Nile Sleeping Sickness area of Uganda. STANLEY, H. M. (1890). In Darkest Africa. London. UGANDA(1909-1910). Annual Reports of Medical Department, 1909 and 1910. -
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S T U D I E S ON T H E E P I D E M I O L O G Y OF S L E E P I N G S I C K N E S S IN EAST AFRICA V.
SLEEPINGSICKNESS IN THE BUNYORODISTRICT OF UGANDA BY
K. R. S. MORRIS, D.SC.* East African Trypanosomiasis Research Organization The Bunyoro District of Western Uganda is bounded by Lake Albert on the west, by the Victoria Nile to the north and east and by the prosperous Mengo, or Buganda District in the south. Lake Albert and the Nile have, for a very long time, served as important routes for canoe traffic. Immediately north-west of Bunyoro lies the West Nile District, at one time the Lado Enclave of the Sudan, with a very primitive population. Large numbers of these people, from 25,000 to 30,000 annually in recent years, pass through Bunyoro to work in the rich coffee, sugar and cotton growing areas of Buganda and Busoga. Both the West Nile and the Busoga Districts have been the scene of severe epidemics of sleeping sickness in the past 30 years. Thus, although Bunyoro, at the beginning of this century, suffered from a sharp epidemic which was brought quite soon under effective control, it has never been entirely free from trypanosomiasis since then, a penalty for its geographical position. Some interesting features in the epidemiology of sleeping sickness can be learned from a study of this District. FIRST APPEARANCE, AND THE EPIDEMIC OF 1904-1914 The first recorded appearance of sleeping sickness in Bunyoro was the case, admitted to Entebbe Hospital in August, 1904, of a Swahili sailor working on the Butiaba-Wadelai steamer. He had been 2 years on this service, which led to the suspicion that his infection had been acquired locally, and, with the alarm of the Lake Victoria epidemic then at its height, gave rise to an immediate search for cases in Bunyoro, particularly along the rivers Victoria and Albert Nile. The Medical Officer at Hoima, Dr. Pooley, collected 18 cases from the Bugungu area in north-west Bunyoro, from " Mwanga's shamba," lying in the angle between the Weiga River and its tributary the Izolya, draining into Lake Albert 20 miles south of the Nile. Dr. Greig, in a search in the villages situated on the Victoria and Albert Niles from the Murchison Falls to Nimule, found four cases between Fajao and Kimori (7 miles from the mouth of the Victoria Nile), one at Wadelai, and one from Duffle in the then Lado Enclave, now the West Nile District (GREIG, 1905). * It is a pleasure to acknowledge the help given by the Uganda Medical Department and Tsetse Control Department during this investigation, and in particular the most valuable co-operation of Dr. G. Timmis, then D.M.O. Bunyoro, in the difficult task of tracing information on the spot.
586
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Map of Uganda to show the track of the epidemic. All place-names in the text are shown. Investigation of the Bugungu area by ADAMS (1907), in the following year, 1905, showed that a fairly severe epidemic was already well established on the lower Weiga River, with at least 200 deaths attributable to sleeping sickness during the past few months. Infection was with Trypanosoma gambiense, and the vector, Glossina palpalis, was observed to be abundant on the Weiga and Izolya rivers. T h e epidemic was found to be localized in a group of about a dozen villages situated on and between these two rivers, with the location of Dr. Pooley's original 18 cases, Mwanga's shamba, right in their midst. Mortality was, in many places, severe, as can be seen from Dr. Adams's list of villages where infections were found :
On Weiga River. Kitagania Kiriangandwa Kiperi Kiewata Mkondo Salizi Kibamezi Buseswa Kinyambezu Kakora
On Izolya River. 6 of 12 died 12 of 30 died 12 of 25 died All dead Evacuated 50 of 60 died 5 of 20 died 25 of 40 died 8 of 60 died 5 of 100 died
Baramweli Mutumbwa Kitchwanti
7 deaths past 3 months 5 deaths past 3 months 5 deaths past 3 months
M a n y of these villages can be seen on an Ordnance Survey map compiled in 1905 (KXNG, 1912), which shows clearly the distribution of what must have been an extensive population living, at that date, in this north-western quarter of Bunyoro and along the
K. R. S. MORRIS
587
valley of the Albert Nile as far as the Sudan frontier. Only two of the villages mentioned by Dr. Adams, Kakora and Mutumbwa, can be traced today. No more cases were found on the Victoria Nile but an advanced case was seen at Koba, in the corner of Acholi between the Victoria and Albert Niles (HoboES, 1907), the scene of a severe outbreak 4 years later. Although the progress of the epidemic on the Albert Nile can be followed (MORRIS, in press), detailed reports for Bunyoro are missing for the next few years, but the development of a more extensive and quite severe epidemic in this District can be seen from records summarized in the Uganda Medical Department's Annual Reports, which give the numbers of deaths from sleeping sickness in Bunyoro for the next 15 years as follows : 1906 1907 1908 1909 1910 1911 1912 1913
369 deaths 170 ,, 461 ,, 254 ,, 277 ,, 168 ,, 84 ,, 41 ,,
1914 15 deaths 1915 11 ,, 1916 7 ,, 1917 8 ,, 1918 5 ,, 1919 5 ,, 1920 2 ,,
Confirmation of these figures and information on the extent of the epidemic, which involved the greater part of the Weiga River system as far east as Kikoroto and both banks of the Victoria Nile, was obtained in histories gathered during the present investigation from a number of older inhabitants who were interviewed in places as widely separated as Atura, Bulisa and Wansiki in Bugungu, Masindi and Hoima. The recorded figures will represent only a proportion of the incidence in the district during this period. The infected areas were difficult of access, and only a few medical and health staff could be spared for this district from the far more disastrous Lake Victoria epidemic. For example, there are no records of the course of the epidemic along the shores of Lake Albert, but a lively and intelligent old man, Ezekeya Bwamgiregu, living at Kibiro, a salt-working village 12 miles S.S.W. of Butiaba, gave a most coherent and lucid history, much of which was confirmed independently by the Saza Chief of Masindi. At the beginning of the century the shores of Lake Albert held a very big population, not only in the larger villages which still exist today, but almost continuously in between, engaged in fishing and salt production, trading mainly with the Congo. Sleeping sickness came in from the north, from Bugungu, at a date which could only be given vaguely, 1906-12, and spread rapidly southward along the lake shore, from village to village, finally reaching the head of the lake in Mubende District. Mortality was heavy. Butiaba lost more than half its population ; Kibiro was reduced from over 1,000 people to 250. In the smaller settlements and camps most of the people died. There was a general movement away from the infected places and most of these people settled above the escarpment, and returned to the five or six main fishing ports only after 10-15 years. The Kibiro informant gave a clear and unmistakable description of the symptoms of sleeping sickness in his account, and quoted the local name for the disease, " okuhungira " meaning " nodding." The table given above shows also the effect, in checking the Bunyoro epidemic, of the measure of removing the population from the shores of Lake Albert and banks of the Victoria and Albert Niles, which was decided upon in 1908, and put into operation in 1909 and 1910 (Uganda, 1909, 1910). Although this measure brought what might have been a much larger epidemic under control, with a striking and progressive reduction in the number of deaths from 1912 onwards, yet the area over which it was applied was undoubtedly excessive, G
588
SLEEPING SICKNESS IN BUNYORO DISTRICT, UGANI~tA
and has caused the subsequent loss of enormous tracts of country to the game tsetse. For example, there were no G. palpalis along the 7 miles of Victoria Nile flanking the delta into Lake Albert, or along the lake shore as far as the river Weiga. The people assert that there was no sleeping sickness there, either. Yet all the population of this richly productive sector of Bugungu was removed. The value of this area for both cattle and fishing was remarked upon by BAKEa (1869) in his journey in 1866, and is remembered by the older inhabitants today. Fishing is recovering, with an extremely prosperous port with 300 canoes at Wansiki, right on the delta, and there were some herds of cattle. But the vast belt of G. morsitans and G. pallidipes which now stretches right across northern Bunyoro is a direct result of the drastic removal of the people in 1910. The country along the Victoria Nile, from Atura to its mouth, was continuously populated and well cultivated up to that time (Map given by King, 1912). There are two possible routes whereby the infection giving rise to this early epidemic could have entered Bunyoro. It could have come gradually eastward from the Congo and have been present for some time as an undetected endemic on the Albert Nile, or it could have been carried rapidly north-westward from the Lake Victoria epidemic after its start around 1896, by Baganda and Banyoro traders who used to move freely to and from Bunyoro at that time. The former theory, of direct introduction from the Congo, has the more convincing evidence in its favour. The facility with which T. gambiense can be introduced by mass movements of people coming from or through infested areas has been shown in the Acholi-Lango studies and by work in West Africa (MoaaIs, 1951, 1959). In 1887 Stanley, with 500-800 followers, arrived on the G. palpalis infested western shores of Lake Albert after having passed during the previous months through long reaches of the Congo heavily infected with sleeping sickness. STANLEY(1890) records that many of his porters were very sick on their arrival at Lake Albert. It is almost inconceivable that this movement could not have introduced some infections and established them in the country west of Lake Albert at this time, also on the Albert Nile as far as Wadelai, reached by one contingent of Stanley's expedition in their relief of Emin Pasha. Emin Pasha's disbanded army and their camp followers subsequently settled at one of Stanley's old camps, Kavali's, just west of Lake Albert, before they were brought by Lugard and settled in Buganda and Busoga between 1891 and 1895. The timing of this movement, of 7,000-8,000 people, fits adequately with the start of the Busoga outbreak on Lake Victoria in 1896, assuming that some of Emin Pasha's rabble brought infection with them from the neighbourhood of Lake Albert. When the earliest evidence from Bunyoro is examined the timing is also correct for a direct introduction here from the Congo. When, in 1905, Dr. Densham investigated closely into the earliest occurrences of sleeping sickness on the Albert Nile, near Wadelai, Emin Pasha's former headquarters, he met with several advanced cases which might have been infected for 4-5 years ; he found a village, Ajei's, which had already been wiped out by sleeping sickness with little trace left, indicating a long duration of the disease here ; and he found that a large proportion of his cases were coming from the Congo. The inhabitants stated that sleeping sickness had been known previously at Logwarri, on the Kiboli River, in the Lubari Province of the north-eastern Congo, and had been introduced from there (HoDQES, 1909). Here is a continuous sequence of records of the disease on the Nile and its neighbourhood just north of Bunyoro up to the date of the infected Swahili sailor and the first batch of Bunyoro cases in 1904. Thus, of the two theories the simplest, and to me the most acceptable, is that when the Bugungu outbreaks were discovered in 1905 the disease
K, R. S. MORRIS
589
had already been present here and on the Victoria and Albert Niles for a number of years undetected, having arrived here directly from the neighbouring loci in the Congo. The longer route, back from Lake Victoria by the medium of southern Mengo and Busoga traders after infection had reached their country from the Congo, involves more speculation and has less evidence for its support. RESETTLEMENTOF THE LAKEALBERTSHORES, 1920 The period of low and steadily decreasing incidence, from 1916 to 1920, led to a move for resettling the vahable lake shore land which had been evacuated in 1909. In 1920 Dr. Hale Carpenter found only one case when he examined 650 people, formerly from Bugungu, settled in the Waki River area, so the whole of the Bugungu coast was opened for fishing and that stretch north of the Weiga River made available for inhabitation. South of Butiaba and Kibero, which had never been evacuated, the ports of Kaiso, Tonya and Buhuka were re-opened. Resettlement in these areas continued during the next 3 years, with annual inspection of the inhabitants, who were found completely free of infection, with the exception of two or three long-standing cases in persons who had returned with the infection in them from the Waki River close to Butiaba. Bugungn had over 1,000 settlers by 1925, but the interior, along the Victoria Nile and Weiga River and its tributaries, was never opened because of the heavy G. palpalis concentrations along these rivers. This land now constitutes the southern half of the Murchison Falls National Park. PERIOD OF INTRODUCTIONS, 1940-55 There is an almost complete blank, which the present investigation was unable to bridge, in the information from Bunyoro from 1925 to 1940. No records of trypanosomiasis cases can be found anywhere. The recording of data for this, as for several other districts, is often so haphazard that the absence of recorded cases cannot be given factual interpretation, one cannot even be sure that it means that no outbreaks occurred. In all probability it does mean that the disease was rare, trypanosomiasis was still causing grave concern in the country to the north and we know that the annual inspection of the inhabitants of the fishing ports from Butiaba southward was still kept up. In the few years for which information is available, 1937, 1939 and 1940, no cases were found on these inspections. From 1941 to the time of writing a fairly continuous, though not necessarily complete, series of records has been obtained. As will be explained below, the disease during this period was being introduced from the epidemic sources outside Bunyoro by the stream of migrant labourers passing through the District. Up t o 1940 the main source was of T. gambiense from the West Nile and Acholi Districts to the north. But in 1941 T. rhodesiense appeared in sudden epidemic form in the Busoga and Mengo Districts to the south, introducing a second potential source with a different pathogenic agent (MAcKIcHAN, 1944). The question now arises of assigning the cases between 1941 and 1955 to one or other of these trypanosomes, and diagnosis between them is still a matter of great difficulty and not entirely free from controversy among the experts. Diagnosis in the local hospital or dispensary can rarely supply the answer, even the laboratory method of 10 years ago, of deciding by the presence or absence of post-nuclear forms, is no longer accepted. For example, in an outbreak centred on Kikora, which will be described below, rats inoculated from four patients from the same village and found infected at the same time, received the laboratory d i a g n o s i s - two T. rhodesiense, two T. gamln'ense. Not only was it extremely improbable for one locality to be
590
SLEEPING SICKNESS IN B U N Y O R O
DISTRICT~ U G A N D A
suffering from a mixed epidemic of these two trypanosomes, but T. gambiense could be definitely ruled out by the absence, proved by extensive search, of its vector, G. palpalis, everywhere in the neighbourhood. The Bunyoro cases during this period of introductions are, therefore, differentiated on epidemiological grounds, to two series which are called T. gambiense, occurring in two main periods, 1941-44 and 1953-57, along the Victoria Nile and Lake Albert shore, where the vector G. palpalis was present ; and to two groups of T. rhodesiense, in 1942 and 1948-50, either among the labourers returning from the Busoga area infected with the species or in the villagers of a locality just off the main route, where G. morsitans and G. pallidipes, both known vectors, were in close contact with the infected villages. 1)
T. gambiense from the North
In 1941 four cases were reported, two coming from lake-shore villages south of Butiaba, one found among the Butiaba railway staff, and a woman just arrived from the West Nile who was found infected in Masindi. There was no doubt that she had brought the infection with her from the West Nile District. At that time this District was just recovering from its second severe and wide-spread epidemic of T. gambiense. In 1942 a fisherman from the village of Kijumbura, on the Victoria Nile 20 miles south of Atura Ferry, was found infected, and a year later three more cases were reported from this village and one from Mutunda, on the Bunyoro side of the ferry. In 1944, 20 cases were treated from this area. It is extraordinary that no details could be found in the files or reports of any kind of what must have been quite a heavy epidemic. Even the following year, 1945, had no cases recorded from Bunyoro although it is difficult to believe that T. gambiense infections would have died out so completely. It is likely that some of the 12 cases reported from " Other Districts " in the Medical Department's Annual Report for 1945 may have originated here. The story of this epidemic was only obtained by seeking out information on the spot. The main information came from a venerable ex-chief, Zakalija Mwanza, and from the Assistant at Mutundu Dispensary, Philip Okello ; but a number of other interviews were made from which the following picture was built up. The outbreak was centred on the village of Kijumbura, situated close to the Victoria Nile from which the inhabitants obtained their water, coming into close daily contact with G. palpalis in doing so. There was a ferry across the Nile to Lango District, but this was abandoned after the outbreak. The onset corresponded with the first recorded case, in 1942, when people from Kijumbura started dying, and continued to do so for the next two years. In 1944 at least 50 deaths occurred, a high figure considering that no notice of such a calamity could be found in official records, but on which very close agreement was found between the various sources of information consuited on the spot. The majority of the inhabitants of Kijumbura were said to have died of sleeping sickness, and a smaller number of deaths occurred in surrounding villages. The survivors left for the villages of Panyadwoli and Koki further north, towards Mutunda, where they are living today, and some, originally Langos, returned to their own country. Apparently the sickness, which was well described by the people, died out as soon as they had moved from the infected area. In fact this is unlikely to have happened in sleeping sickness due to T. gambiense, whose development in the patient may take 2 to 3 years, more probably it was just not reported, as the very meagre documentation of the 1944 outbreak would indicate. Confirmation of the more prolonged and extended nature of this epidemic has just been obtained by the D.M.O. Bunyoro, Dr. Timmis, after talking to an ex-chief of Koki, by name Oyuru. Oyuru confirmed the heavy deaths around Kijumbura, which
K. R. S. MORRIS
591
included three chiefs whom he named, and stated that the sickness then spread northwards as far as his village of Koki, where further deaths occurred, with the epidemic lasting till 1945. The names of people sent from Koki to Masindi Hospital were given. Occasional cases continue to be brought in from north-eastern Bunyoro, from the Nile or the Tiff River near Kirandongo, with several coming from the adjoining Maruzi and Oyam counties of Lango. In 1953 there were five cases from villages near the Nile and one from Lango, in 1954 there were two from Mutunda area and three from Lango, and in 1955 a single case from near Kiryandongo. That is the last reported case of trypanosomiasis in Bunyoro. The appearance of T. gambiense in this district in 1941 was almost certainly due to its introduction from the heavily infected West Nile District. Some 4,000 cases had been treated there during the previous 6 years, with 373 and 304 new infections occurring in 1940 and 1941. Seven thousand labourers from West Nile and over 5,500 from the Congo and Sudan passed through Bunyoro in that year to work in Mengo and Busoga, and this number would be bound to include some undetected T. gambiense cases, which would have every chance of passing on an infection, either at some point on the Lake Albert shores or at one of the Victoria Nile ferries. There are the known cases of the infected woman from the West Nile, diagnosed on reaching Masindi in 1941, and of an Asian from Butiaba who was found to be infected on his return from Pakwach a few years later. It is much less likely that the more recent infections, of 1953-55, were introduced in this way, the West Nile trypanosomiasis incidence was below 10 cases per year then, and in Lango and Acholi equally low. It is much more likely that trypanosomiasis never disappeared from N.E. Bunyoro, smouldering on at a low incidence in villages on both sides of the Nile here. Two of the cases in 1953 came from Alero, a small village 5 miles off the main road N. of Mutunda, right on the banks of the Nile with G. palpalis infested water supplies occurring within 100200 yards of many of the houses. There was regular communication across the river with Lango. The northern end of the village is almost opposite Kamdini, where a fisherman was found infected in October, 1957, and where Dr. Snell records a case, certainly infected locally, in 1950. G. palpalis is present all along this part of the Nile from Atura to Kamdini Falls, where it is abundant. There are many Lango and Acholi settlers among the villages on the Bunyoro side of the river, and, apart from the occupation of fishing, there is a constant traffic across the Nile between the people on both banks. The river may represent a political boundary ; both biologically and in the life of the people it is a single, natural unit. As such it constitutes the centre of the trypanosomiasis problems in this locality, which can be correctly assessed only with this fact in mind. T. rhodesiense from the South The position of Bunyoro, traversed by much frequented labour routes coming from an infected area to the north, with the consequent introductions of infections of T. gambiense, had made the Medical Officers alive to this danger. When the T. rhodesiense epidemic in Southern Busoga developed in 1941, with its original focus on the Kakira Sugar Estate near Jinja which employed much of this labour, a new threat developed to Bunyoro, this time from the south. Consequently inspection posts were established on the main points of entry of labourers returning from Busoga and Mengo, so that they could be examined for trypanosomiasis. This action was amply justified. An extensive, heavily infested belt of G. morsitans, 12-15 miles in width, existed at that time between the Kafu River and Victoria Nile at Masindi, 2)
592
SLEEPING SICKNESSIN BUNYORODISTRICT, UGANDA
and was traversed by these labour routes, which also came in contact with one or more of the much less extensive pockets of G. pallidipes. In 1943 three West Nile labourers, returning direct from the sugar estates, were found to be infected on examination at Masindi Port. The infection was undoubtedly T. rhodesiense, and because of the foresight of the Medical Department, no local outbreak developed. In 1948, however, a Muganda from Nabiswera, who had recently been working in Busoga and Bukedi, was picked up at the Kibangya post with T. rhodesiense infection. Later the same year three cases with the same infection were discovered at Kikora, a bush village 10 miles south-west of Kibangya, surrounded by heavy G. morsitans belt and flanked by a patch of G. pallidipes. Vigorous search of the area from Kijunjubwa to Kibangya made it possible to detect and stamp on at once a small outbreak of 10 cases in 1949, centred around Kikora. Only two cases were found in 1950. after which no more occurred. There is no doubt that these cases were all T. rhodesiense infections. A suspicion that some might be due to T. gambiense led to a thorough search for G. palpalis, particularly on the Kafu River, by Mr. Bernacca of the Tsetse Control Department, but none was found nearer than its junction with the Victoria Nile. At the same time the D.M.O. for Mengo reported two more cases in 1949 from Nabiswera and a village close by, making a total of three from this locality in 6 months, at least one in an old woman who had never been away from her home. Nabiswera, 17 miles from Kibangya, was at that time closely flanked by belts of G. pallidipes and G. morsitans, and these occurrences, which were found not on a search for trypanosomiasis but on the patient coming with " fever " to the local dispensary, make it clear that T. rhodesiense was being actively transmitted on both the Mengo and Bunyoro sides of the Kafu River at that time. It was most fortunate, and perhaps saved a more serious outbreak, that the Tsetse Control Department's operations for the control of G. pallidipes and G. morsitans by hunting had reached the Nabiswera area by 1949 and was extended into south-eastern Bunyoro in 1951. By 1954 both these species of tsetse had been eradicated from the country from Kijunjubwa to Masindi Port and the danger of further T. rhodesiense introductions by the migrant labour passing this area no longer exists. The course of events during this period of introduction, leading to small, local outbreaks of short duration, can be more easily followed in the following simple table, in which all the records obtained from the Medical Department's reports and files have been set out to show the locality of the infection or at least the place where diagnosis was made. SUMMARY AND CONCLUSIONS
A review of the events just described makes it possible to give an appraisal of the position in Bunyoro regarding trypanosomiasis today, and assess any probable dangers that exist or might arise. The first records of sleeping sickness in Bunyoro District are in 1904, when the diagnosis of an infection in a sailor on the Butiaba-Wadelai steamer led to the discovery of a score of cases in Bugungu area, lying in the angle between the north-eastern shore of Lake Albert and the Victoria Nile. G. palpalis was widespread, and infection must have been with T.
gambiense. In 1905 it was found that quite a severe epidemic was established in Bugungu, centred on a section of the Weiga River, 20 miles south of the Nile, where it was closely populated and heavily infested with G. palpalis. At least 200 deaths from trypanosomiasis had occurred in recent months.
K. R. S. MORRIS
Year
Locality of infection or diagnosis
593
Bunyoro Total G = T. gambiense R h = T. rhodesiense
1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957
3 Lake Albert fishing ports. 1 woman ex W. Nile 3 labourers ex Busoga diagnosed Masindi Port 1 Kijumbura fisherman 3 Kijumbura, 1 Mutunda 20 Kijumbura & area. 1 Masindi Port, 1 Bisso near Butiaba No records, but probably cases present, viz. 12 in Med. Ann. Report under " Other Districts " No records Inspection Lake villages showed no cases 1 Butiaba who had contact with West Nile 1 Kiryandongo 3 Kikora. 1 Baganda from Nabiswera 10 Kikora-Kibangya area on Kafu River (2 cases Nabiswera recorded M.O. Mengo) 2 Kikora area 1 case Kamdini (Lango) No records No records 2 Alero. 1 Mutunda. 2 S.W. of Mutunda. 1 Akokoro (Lango) 3 ex Maruzi (Lango) diagnosed Masindi Port. 1 Mutunda. 1 Kiryandongo 1 S.W. Mutunda 1 case Kamdini (Lango)
4G 3 Rh 1G 4G 22 G
2G 4 Rh 10 Rh 2 Rh
1G
6G 5G 1G 0 1G
During the next 5 years a much wider epidemic developed throughout the greater part of the Weiga River, and along both banks of the Victoria Nile, which was well populated for most of its length at that time. F r o m 200 to 460 deaths a year were reported between 1906 and 1910. F r o m this north-western Bunyoro outbreak the infection spread southwards along the shores of Lake Albert and decimated the fishing population which formed an almost continuous line of settlement from Butiaba to the southern end of the Lake. T h e epidemic was dealt with by the removal of the populations of Bugungu, the Victoria Nile, and the Lake Albert shores, in 1909-10. This had a rapid effect in reducing the n u m b e r of cases, until, in the five years 1916-20, an average of only 5.2 deaths per year were recorded from Bunyoro. Investigations by the early workers and the local evidence they obtained indicate that sleeping sickness had been in existence on the Albert Nile for a good many years before 1904, from its source in Lake Albert to Wadelai, the headquarters of Emin Pasha, and that its earliest introduction was probably from the eastern Congo. By 1920 the comparative freedom of this district from any infections led to the resettlement of Western Bugungu and of the lake shores south of Butiaba, but an immense stretch of northern Bunyoro was left uninhabited, and at present contains only game, G. morsitans and G. pallidipes. Most of this area now lies within the Murchison Falls National Park. Data for the period 1925-1940 are almost completely lacking. It is unlikely that any major outbreaks occurred, but beyond that it is impossible to say, as records from 1941 show
~94
SLEEPING SICKNESS IN BUNYORO DISTRICTp UGANDA
clearly the introduction of cases by labourers from West Nile, which had then had a severe epidemic for 6 years. In 1944 a small epidemic of T. gambieme infection broke out on the Victoria Nile 20 miles south of Atura Ferry, in which 20 cases were diagnosed and treated, but at least 50 deaths had already occurred. The outbreak was centred on one small village, Kijumbura, close to the Nile, where there was intimate contact between the people and G. palpalis, and it ended abruptly after most of the inhabitants had died and the rest had moved away. It is probable that T. gambiense has remained in very low endemic form, often unnoticed, on this section of the Nile, where there are a number of villages in close contact with G. palpalis and where, taking both Lango and Bunyoro banks as the epidemiological unit, trypanosomiasis has hardly been absent during the past 15 years. There were six and five cases in 1953 and 1954 respectively, one in 1955, and one from Lango in 1957, occurring right opposite the location of two of the 1953 cases. A threat of introduction of trypanosomiasis from the south came with the T. rhodesiense outbreak of 1940 in Busoga, but the foresight of the Medical Department in examining northward-returning labour at the main points of entry into Bunyoro averted this danger until 1949, when a small outbreak of 10 cases of this infection occurred at Kikora, just south of the point where the Kampala-Masindi road, used by much of this labour, crosses the Kafu River. G. raorsitans and G. pallidipes occupied a wide zone of country on each side of this river, but there was no G. palpalis. Three T. rhodesieme cases were found at Nabis, wera in Mengo at the same time, and there is no doubt that this infection was endemic on both sides of the Kafu River at that time. The elimination of both species of testse from the whole of this area by 1954 means that this danger no longer exists. An examination of these early events in the light of the knowledge of epidemiology possessed today proves instructive. The only big epidemic in Bunyoro, that of 1904-14, did not originate on either of the Nile Rivers or on the shore of Lake Albert, which offered possible sites with a human population and G. palpalis in contact, but on a part of the much smaller Weiga and Izolya rivers where many villages were clustered about a stretch of river infested with G. palpalis in narrow riverine habitat, a situation which has already become familiar, in Busongora, Acholi and Lango in Uganda, and in Nyanza Province in Kenya. Under the favourable conditions of close and repeated man-fly contact in this early focus the epidemic rapidly developed, as the number of recorded deaths show, and spread throughout the places where there was a fairly high human population in contact with G. palpalis, that is up the Weiga and its tributaries, along the Victoria and Albert Niles, and along the shores of Lake Albert. The removal of the populations from these danger zones has changed the whole picture since then. Along the Nile from Kamdini to Fajao and throughout practically the whole of the Weiga River system, which lies in the National Park, there are no inhabitants, and, except for the 15 miles of Bugungu coast where there is no G. palpalis, the population along Lake Albert is greatly reduced in numbers and confined to a few widely spaced and comparatively small villages. The effect of depopulation on tsetse was to cause an immense increase in the numbers and distribution of the game-feeding species, G. morsitans and G. pallidipes which now occupy vast tracts of the country that held thriving populations with their cattle up to 50 years ago. The distribution of G. palpalis remains substantially the same. This species occurs all along the Victoria Nile from Lake Kyoga to 6 or 7 miles below the Paraa Ferry, with a rather broken distribution associated with the presence of riverine forest or evergreen fringing
K, R. S. MORRIS
595
thicket. It is absent from the lowest 7 miles of the Nile and from the shores of Lake Albert from this point to south of Butiaba, but abundant on all the rivers flowing into this section of the Lake, from the Weiga to the Waki. South of Kibero G. palpalis is present almost continuously in the evergreen lakeshore vegetation. It seems to be entirely absent from the Kafu River. During the present investigation this species was caught with ease and in numbers indicating permanent fly communities on the Nile north of Atura Ferry and at the Paraa Ferry, and troublesome swarms were met with from here to the Murchison Falls. G. palpalis was encountered again in numbers south of Kibero, and was a pest to passing canoes and in fishing camps. This species represents a danger, however, only when it is in close contact with a fairly dense and extensive human population, such as that which existed before the epidemic on the Weiga and along the Lake Albert shores. The welt populated parts occur today only around the few more important centres, such as Masindi and Hoima, from which extensions of fairly well populated land stretch out along the main roads. These populations are not in close contact with G. palpalis with the exception of those from Masindi Port to north of Atura Ferry and the lake-shore fishing villages south of Butiaba. In both these areas the population is small and discontinuous, i.e. is not of the pattern which experience elsewhere shows to be associated with the development of outbreaks of T. gambieme. It is possible to say, then, that since the time of the first epidemic the intrinsic danger from T. gambieme in Bunyoro has become greatly reduced. The main danger is now extrinsic. There are still populations, although small, in contact with G. palpalis. Outbreaks of this trypanosome did occur in an adjoining District from which came much frequented labour routes, making its introduction almost a certainty. Under these conditions what have been described as "secondary" or " peripheral " areas of infection (Moams, 1951) can, and did develop in Bunyoro, dependent on the introduction of infections from the true endemic foci outside. With the great extension of G. morsitans and G. pallidipes, a potential danger from T. rhodesiense also arose, which became real with the onset of the Busoga epidemic, at the other end of the labour route, in 1940. Although this danger has been offset by tsetse control in south-east Bunyoro it still exists in many other parts of the District, the game tsetse are still uncomfortably close to Masindi and come almost right up to Butiaba, where thousands of labourers returning from Busoga are embarked. The recent diagnosis of a case of T. rhodesiense infection from Pakwach, in a labourer who had just returned from Busoga and must have passed through Bunyoro, demonstrates the reality of this risk. It seems as if in recent years conditions have become more suitable for the establishment of endemic T. gambiense infection along parts of the Nile, from its exit from Lake Kyoga to Kamdini Falls. The population there is closely associated with the river and is evidently on the increase. But, as has already been pointed out in the description of this area, the Nile is a natural biological unit and a centre for human activities, and not a boundary. It is this fact which counts in the epidemiology of trypanosomiasis, not District limits. It was shown how, in 1949, the T. rhodesiense outbreak concerned Mengo as well as Bunyoro. Similarly the Nile endemic of T. gambiense at the present time involves parts of the Districts of Acholi and Lango as well as Bunyoro. Practical advice on this situation need be neither profound nor prolonged. The danger spots today are : (i) Intrinsically, the Nile from Lake Kyoga to Kamdini, to which should be added the Titi River near Kiryandongo.
596
SLEEPING SICKNESS IN BUNYORO DISTRICT~ UGANDA
(ii) Extrinsically, the above areas are also concerned, and possibly the lake-shore villages south of Butiaba, in the event of a West Nile outbreak developing or the Aswa River epidemic extending ; and, in view of the amount of T. rhodesiense still in Bukedi and Busoga the population fringing the northern and western G. morsitans and G. pallidipes belts should be watched. The more important fringes are along the Masindi-Atura road, the area between Bisso and Butiaba, and the eastern and southern fringes of occupied Bugungu. Insurance against the intrinsic danger can be most readily effected by making a survey, on both Lango and Bunyoro sides of the Nile, of villages within say 5 miles of the river in Maruzi and Oyam counties in Lango and Kibanda county in Bunyoro. To use a single joint organization would be the economical way to effect this survey. The need for control measures, and their formulation, if needed, can be based on the factual data thus obtained. It is almost trite to say that an effective attack on the sources of infection themselves, in West Nile, Lango and Busoga-Bukedi, deals at once with those problem spots and removes the extrinsic dangers not only to Bunyoro but to the several other parts of Uganda where the introduction of trypanosomiasis could occur. Even if this advice be considered as involving much trouble and expense it must be remembered that the task of controlling migrant labour and traders is itself a great trouble and is often almost impossible or extremely cumbersome to enforce. It must also be borne in mind that the stream of labourers passing through Bunyoro in both directions now numbers from 25,000 to 28,000 per year, the numbers have trebled in the past 15 years. The past history of sleeping sickness in East and in West Africa is full of instances in which big developments or increases in movement and ease of transport have brought about fresh outbreaks of this disease. REFERENCES
ADAMS,E. B. (1907). Rept. Sleep. Sickn. Comm. Roy. Soc., 8, 100. BAKER,S. W. (1869). The Albert Nyanza. London. Gm~IG, E. D. W. (1905). Rept. Sleep. Sickn. Comm. Roy. Soc., 6. 273. HODGES,A. D. P. (1907). Ibid., 8, 86. - (1908). Ibid., 9, 3. KING, H. H. (1912). Bull. ent. Res., 3, 92. MAcKIcHAZ~, I. W. (1944). Trans. R. Soc. trop. Med. Hyg., 38, 49. MORRIS, K. R. S. (1951). Bull. ent. Res., 42, 427. (1959). Trans. R. Soc. trop. Med. Hyg., 53, 384. in press. The West Nile Sleeping Sickness area of Uganda. STANLEY, H. M. (1890). In Darkest Africa. London. UGANDA(1909-1910). Annual Reports of Medical Department, 1909 and 1910. -
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