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Tsetse Flies and the Development of Africa
951
THE LANCET LONDON:SATURDAY, JUNE 19, 1948s
in the week and within what geographical limits, he is prepared to. do so, and whether he will accept emergency calls. General practitioners will receive a list of the participating specialists, giving the name and telephone number of the through which each can be called, and the hospitals concerned will serve as bureaux with a clerk on duty day and night. In an urgent case, if the practitioner asks for a particular specialist, the clerk will inquire whether an alternative specialist would be acceptable if the first cannot come ; and if none of the specialists on the hospital’s list is available he will if needed seek help from a neighbouring hospitalWhere there is no great hurry, the practitioner will normally want to have the help of a particular specialist and will be prepared to wait until the next day when that specialist is free to take a non-urgent call : the clerk will ascertain his preference and the proposed day and time of the visit, and will make appropriate arrangements with the specialist; while the practitioner, on his side, will be asked to send to the hospital a brief note about the case for the specialist’s information. The hospital management committees will be responsible for keeping this machinery moving, and part of their duty will be to keep records of calls and submit them, with claims for travelling and other expenses, to the regional hospital board, which will make the
hospital
Admission and Visit THE four regional hospital boards for London have explained that when they take over the hospitals on July 5 there will be as little change as possible in the admission of patients, which will normally be arranged directly between the practitioner and the hospital. But beds are so scarce that provision must be made for cases where direct application fails, and the metropolitan boards have therefore asked King Edward’s Hospital Fund to expand its Emergency Bed Service, which for many years has been successfully arranging difficult admissions. Acting as the boards’ agent, the E.B.S..will eventually organise an admission system throughout the four large metropolitan regions, establishing local admission centres where needed. For non-urgent cases, hospitals will maintain waiting-lists as at present, and will notify the patient when a bed is free. For certain other groups special procedure is required : thus recommendations for admission of tuberculous patients will usually go to the board itself through a tuberculosis officer; in mental cases admission will be arranged either by the " duly authorised officer" of the local health authority or directly with the mental hospital itself ; and in maternity cases the E.B.S. willdeal only with emergencies. Admission of infectious diseases will be undertaken by the E.B.S., but application should be made through the medical officer of health. In cases of chronic illness rigid selection is but if the practitioner fails to bed the E.B.S. will do what it can to help. Related to the problem of admission is that of home visiting. The fact that in the new service specialist advice may be had without payment will encourage patients (or their relatives) to ask for a second opinion, preferably delivered in their own home ; and excessive demands of this kind could of course threaten the efficiency of the whole service, which depends on economical use of the consultant’s time. We may hope eventually for development of domiciliary visiting, which apart from advantages to the patient is capable of reducing the strain on hospitals; and there is every reason’for experiment on the lines suggested by Dr. HARWOOD STEVENSON.1 But until the number of specialists is greater, the service is most likely to work if everyone understands that specialist advice is obtainable only at the hospital or clinic unless the patient’s condition prevents his admission to or attendance as an outpatient. Save in emergency, specialist advice will be procured only through the general practitioner, who will have the unwelcome task of explaining that a specialist cannot be summoned unless there is really some good reason. The mechanism to be used for bringing a consultant to the patient’s home has now become rather clearer. Hoping for the answer "yes," the regional hospital board will ask every specialist at a non-teaching hospital in its area (the boards of governors doing the same in teaching hospitals) whether he will undertake such visits, and (if so) at what times
unfortunately necessary, secure a
hospital
1
Lancet, 1947, i, 532
payments.
Pending’ agreement
the boards
are
on
permanent scales,
authorised to pay 4 guineas for
a
consultation, 5 guineas for a visit involving a minor operation, and 10 guineas for a visit involving a major operation-not more than 100 guineas being paid to any one doctor during a quarter. These arrangements are provisional and experimental. What is necessary is to work out in practice a scheme for saving the time and energies of the specialist and of the family doctor, without erecting obstacles between them. The service must be protected against unfair demands ; but it is even more necessary that fair ones should be fully and humanely met.
Tsetse Flies and the Development of Africa IN the past sixteen years half a million cases of sleeping sickness (out of a population of 22 million) have been recorded in Nigeria alone ; and this was a period during which medical science has greatly diminished the incidence and gravity of the disease. Sleeping sickness, then, has been and still is a grave menace to the health of the African, especially on the west coast. But this is not the only, or even the most serious, way in which the tsetse fly retards the development of Africa. Nagana, the fatal flyborne disease of horses and cattle, prevents the proper colonisation of vast areas of the continent, Without cattle, the natives are robbed of milk and flesh, and the ox-plough is replaced by the inefficient hoe. As a result, the Africans cling to the fly-free areas, which become over-populated, leading to soil erosion and general poverty. Here, then, is a vast problem to which the Englishman is contributing his scientific skill for the welfare of Africa. Areas which earlier settlers like the Arabs had found impossible to colonise are gradually opening up before the slow conquest of the tsetse. The struggle has progressed ’ only by means of continuous research and its extensive application in the field.
’
952 On June 8 this was the subject of a Stephen Paget lecture to the Research Defence Society by Prof. P. A. BUXTON, F.R.S., who has gained first-hand experience of the work being done on the tsetse in the last three years by making extensive tours of the fly belts in east and west Africa on behalf of the Colonial Office. BuxTON emphasised the size of the problem by pointing out that the territory held by the tsetse, some 4,500,000 square miles, is about twice the area of the U.S.A. or about seventy-five times that of Great Britain. The beginnings of knowledge about the fly and its disease-carrying habits are found in observations of the early explorers. LIVINGSTONE himself, in 1858, made a startlingly accurate guess about the possible carriage of a noxious organism by the tsetse, before the transmission of pathogens by insects was recognised. The discoveries of the carriage of the trypanosome diseases of animals and man were made by BRUCE and others about the turn of the century. But it was not until the inter-war period that a systematic study of the detailed habits and distribution of the various species of glossina was begun by SWYNNERTON and his associates. One of the earliest methods of study was the " fly round," a periodic peregrination with a bait animal, to count the numbers of tsetse coming to feed on it. Useful information about fly density in different areas and at different times of year was obtained; but it was only of a relative nature. Subsequently, JACKSON introduced a method of releasing marked flies and attempting to recapture them at intervals. From the proportions of marked flies in the subsequent captures, after correction, the absolute numbers of flies in a given area could be estimated. Concurrently with work on the flies, research progressed on the trypanosomes and the intricate problems of infection of the fly and the cycle in that host. Several methods of fly control have been adopted on the basis of the research findings. One of the most important results .was a good knowledge of the particular habitats of different tsetses. These breeding and resting sites, which Bux2orT illustrated in a coloured film, are often very sharp and specific to certain areas (e.g., strips along rivers or stream banks) or even to certain types of tree and scrub. It is therefore possible to exclude some flies by selective clearing ; sometimes the work merely entails felling a very small proportion of vegetation to The fly-counts eliminate flies from a large area. and the knowledge of the slow breeding habits of the insect have suggested another method of elimination : by simple repeated hand catching. This has been found effective and practical in some isolated sites. A third and highly valuable method of attacking tsetse is by colonisation. The agricultural and other activities of human settlers above a certain densitv will drive away the flies and eventually render the area safe for cattle. If °colonisation is left to the African he will do it patchily, engulfing neglected areas of fly belt because he does not consider them fertile enough. ’This results in maximum contact between the fly and man and his animals and leads tc failure. Government settlement schemes are therefore necessary ; schemes which need careful consideration of tribal customs, agricultural needs, and a host A of other problems unrelated to the tsetse. most successful venture of this kind has been
carried out at Anchau in Northern Nigeria (700 sq. miles). Then there is the method of fly elimination which has aroused misgivings in naturalists and big-game hunters-the systematic destruction of large game in the required area. This method is clearly effective, for some important tsetses, such as G. morsitans, disappear with the game ; and the game animals are the reservoir of trypanosome infection for domestic cattle. The practicability of game clearance has been demonstrated in Southern Rhodesia, where the largest tsetse-fly clearance in Africa has been achieved by this method. Modern insecticides have been brought into use against the tsetse fly and large-scale experiments are still in progress. Perhaps the airplane spraying of D.D.T. or ga:mma-B.H.c. smokes will be found a useful aid in clearing important or localised breeding sites, but the method is far too expensive to be applied to the main problem. The attack on the trypanosome which causes human disease has continued, and curative and prophylactic drugs are being widely used. The prolonged suppression of the parasite which can be achieved suggests that, if the
drugs
are
given
to
a
sufficiently high proportion
of the population, sleeping sickness can be stamped out of some areas by this means alone. BuxTON foresaw that some of these numerous measures now considered promising will perhaps eventually be dropped. But the complexity of the problem seems to demand complex remedies.
Bacteriological
Nomenclature
WHAT’S in a name ? So far as bacteria are concerned there may be much or little. Scientific names are now given to bacteria with the intention of making clear the relationship of one organism with another. This was not always so ; in the last century every rod-shaped organism was called by the generic name Bacillus, which in no way indicated its systematic position. In 1936, at the second congress of the International Association of Microbiologists, the Bacillus was reserved for the aerobic group. But even now some medical students are taught the anachronistic nomenclature of the Bacillus era, and medical journals (ourselves included) still often allow it to invade their columns. It is time that medical bacteriologists, especially teachers, abandoned their names-don’t-matter attitude and learned a little of what systematists throughout the world are trying to do to make the name something more than a label. The modern English usage, as exemplified by Topley and Wilson’s Principles of Bacteriology and Immunity, is based on an interim report of a committee of the Society of American Bacteriologists. In America, nomenclature has evolved from the final report of the same committee, the different stages being represented by successive editions of Bergey’s Manual of Determinative Bacteriology. Topley and Wilson’s classification may be described as a conservative application to bacteria of the binomial system of nomenclature. In the first edition most of the gram-negative rod-shaped bacteria, chiefly of intestinal origin, were placed in an unwieldy genus Bacterium, but the latest edition (1946) recognises the separation of the typhoid-food-poisoning group as the genus Salmonella and the dysentery bacilli as
generic name spore-bearing
THE LANCET LONDON:SATURDAY, JUNE 19, 1948s
in the week and within what geographical limits, he is prepared to. do so, and whether he will accept emergency calls. General practitioners will receive a list of the participating specialists, giving the name and telephone number of the through which each can be called, and the hospitals concerned will serve as bureaux with a clerk on duty day and night. In an urgent case, if the practitioner asks for a particular specialist, the clerk will inquire whether an alternative specialist would be acceptable if the first cannot come ; and if none of the specialists on the hospital’s list is available he will if needed seek help from a neighbouring hospitalWhere there is no great hurry, the practitioner will normally want to have the help of a particular specialist and will be prepared to wait until the next day when that specialist is free to take a non-urgent call : the clerk will ascertain his preference and the proposed day and time of the visit, and will make appropriate arrangements with the specialist; while the practitioner, on his side, will be asked to send to the hospital a brief note about the case for the specialist’s information. The hospital management committees will be responsible for keeping this machinery moving, and part of their duty will be to keep records of calls and submit them, with claims for travelling and other expenses, to the regional hospital board, which will make the
hospital
Admission and Visit THE four regional hospital boards for London have explained that when they take over the hospitals on July 5 there will be as little change as possible in the admission of patients, which will normally be arranged directly between the practitioner and the hospital. But beds are so scarce that provision must be made for cases where direct application fails, and the metropolitan boards have therefore asked King Edward’s Hospital Fund to expand its Emergency Bed Service, which for many years has been successfully arranging difficult admissions. Acting as the boards’ agent, the E.B.S..will eventually organise an admission system throughout the four large metropolitan regions, establishing local admission centres where needed. For non-urgent cases, hospitals will maintain waiting-lists as at present, and will notify the patient when a bed is free. For certain other groups special procedure is required : thus recommendations for admission of tuberculous patients will usually go to the board itself through a tuberculosis officer; in mental cases admission will be arranged either by the " duly authorised officer" of the local health authority or directly with the mental hospital itself ; and in maternity cases the E.B.S. willdeal only with emergencies. Admission of infectious diseases will be undertaken by the E.B.S., but application should be made through the medical officer of health. In cases of chronic illness rigid selection is but if the practitioner fails to bed the E.B.S. will do what it can to help. Related to the problem of admission is that of home visiting. The fact that in the new service specialist advice may be had without payment will encourage patients (or their relatives) to ask for a second opinion, preferably delivered in their own home ; and excessive demands of this kind could of course threaten the efficiency of the whole service, which depends on economical use of the consultant’s time. We may hope eventually for development of domiciliary visiting, which apart from advantages to the patient is capable of reducing the strain on hospitals; and there is every reason’for experiment on the lines suggested by Dr. HARWOOD STEVENSON.1 But until the number of specialists is greater, the service is most likely to work if everyone understands that specialist advice is obtainable only at the hospital or clinic unless the patient’s condition prevents his admission to or attendance as an outpatient. Save in emergency, specialist advice will be procured only through the general practitioner, who will have the unwelcome task of explaining that a specialist cannot be summoned unless there is really some good reason. The mechanism to be used for bringing a consultant to the patient’s home has now become rather clearer. Hoping for the answer "yes," the regional hospital board will ask every specialist at a non-teaching hospital in its area (the boards of governors doing the same in teaching hospitals) whether he will undertake such visits, and (if so) at what times
unfortunately necessary, secure a
hospital
1
Lancet, 1947, i, 532
payments.
Pending’ agreement
the boards
are
on
permanent scales,
authorised to pay 4 guineas for
a
consultation, 5 guineas for a visit involving a minor operation, and 10 guineas for a visit involving a major operation-not more than 100 guineas being paid to any one doctor during a quarter. These arrangements are provisional and experimental. What is necessary is to work out in practice a scheme for saving the time and energies of the specialist and of the family doctor, without erecting obstacles between them. The service must be protected against unfair demands ; but it is even more necessary that fair ones should be fully and humanely met.
Tsetse Flies and the Development of Africa IN the past sixteen years half a million cases of sleeping sickness (out of a population of 22 million) have been recorded in Nigeria alone ; and this was a period during which medical science has greatly diminished the incidence and gravity of the disease. Sleeping sickness, then, has been and still is a grave menace to the health of the African, especially on the west coast. But this is not the only, or even the most serious, way in which the tsetse fly retards the development of Africa. Nagana, the fatal flyborne disease of horses and cattle, prevents the proper colonisation of vast areas of the continent, Without cattle, the natives are robbed of milk and flesh, and the ox-plough is replaced by the inefficient hoe. As a result, the Africans cling to the fly-free areas, which become over-populated, leading to soil erosion and general poverty. Here, then, is a vast problem to which the Englishman is contributing his scientific skill for the welfare of Africa. Areas which earlier settlers like the Arabs had found impossible to colonise are gradually opening up before the slow conquest of the tsetse. The struggle has progressed ’ only by means of continuous research and its extensive application in the field.
’
952 On June 8 this was the subject of a Stephen Paget lecture to the Research Defence Society by Prof. P. A. BUXTON, F.R.S., who has gained first-hand experience of the work being done on the tsetse in the last three years by making extensive tours of the fly belts in east and west Africa on behalf of the Colonial Office. BuxTON emphasised the size of the problem by pointing out that the territory held by the tsetse, some 4,500,000 square miles, is about twice the area of the U.S.A. or about seventy-five times that of Great Britain. The beginnings of knowledge about the fly and its disease-carrying habits are found in observations of the early explorers. LIVINGSTONE himself, in 1858, made a startlingly accurate guess about the possible carriage of a noxious organism by the tsetse, before the transmission of pathogens by insects was recognised. The discoveries of the carriage of the trypanosome diseases of animals and man were made by BRUCE and others about the turn of the century. But it was not until the inter-war period that a systematic study of the detailed habits and distribution of the various species of glossina was begun by SWYNNERTON and his associates. One of the earliest methods of study was the " fly round," a periodic peregrination with a bait animal, to count the numbers of tsetse coming to feed on it. Useful information about fly density in different areas and at different times of year was obtained; but it was only of a relative nature. Subsequently, JACKSON introduced a method of releasing marked flies and attempting to recapture them at intervals. From the proportions of marked flies in the subsequent captures, after correction, the absolute numbers of flies in a given area could be estimated. Concurrently with work on the flies, research progressed on the trypanosomes and the intricate problems of infection of the fly and the cycle in that host. Several methods of fly control have been adopted on the basis of the research findings. One of the most important results .was a good knowledge of the particular habitats of different tsetses. These breeding and resting sites, which Bux2orT illustrated in a coloured film, are often very sharp and specific to certain areas (e.g., strips along rivers or stream banks) or even to certain types of tree and scrub. It is therefore possible to exclude some flies by selective clearing ; sometimes the work merely entails felling a very small proportion of vegetation to The fly-counts eliminate flies from a large area. and the knowledge of the slow breeding habits of the insect have suggested another method of elimination : by simple repeated hand catching. This has been found effective and practical in some isolated sites. A third and highly valuable method of attacking tsetse is by colonisation. The agricultural and other activities of human settlers above a certain densitv will drive away the flies and eventually render the area safe for cattle. If °colonisation is left to the African he will do it patchily, engulfing neglected areas of fly belt because he does not consider them fertile enough. ’This results in maximum contact between the fly and man and his animals and leads tc failure. Government settlement schemes are therefore necessary ; schemes which need careful consideration of tribal customs, agricultural needs, and a host A of other problems unrelated to the tsetse. most successful venture of this kind has been
carried out at Anchau in Northern Nigeria (700 sq. miles). Then there is the method of fly elimination which has aroused misgivings in naturalists and big-game hunters-the systematic destruction of large game in the required area. This method is clearly effective, for some important tsetses, such as G. morsitans, disappear with the game ; and the game animals are the reservoir of trypanosome infection for domestic cattle. The practicability of game clearance has been demonstrated in Southern Rhodesia, where the largest tsetse-fly clearance in Africa has been achieved by this method. Modern insecticides have been brought into use against the tsetse fly and large-scale experiments are still in progress. Perhaps the airplane spraying of D.D.T. or ga:mma-B.H.c. smokes will be found a useful aid in clearing important or localised breeding sites, but the method is far too expensive to be applied to the main problem. The attack on the trypanosome which causes human disease has continued, and curative and prophylactic drugs are being widely used. The prolonged suppression of the parasite which can be achieved suggests that, if the
drugs
are
given
to
a
sufficiently high proportion
of the population, sleeping sickness can be stamped out of some areas by this means alone. BuxTON foresaw that some of these numerous measures now considered promising will perhaps eventually be dropped. But the complexity of the problem seems to demand complex remedies.
Bacteriological
Nomenclature
WHAT’S in a name ? So far as bacteria are concerned there may be much or little. Scientific names are now given to bacteria with the intention of making clear the relationship of one organism with another. This was not always so ; in the last century every rod-shaped organism was called by the generic name Bacillus, which in no way indicated its systematic position. In 1936, at the second congress of the International Association of Microbiologists, the Bacillus was reserved for the aerobic group. But even now some medical students are taught the anachronistic nomenclature of the Bacillus era, and medical journals (ourselves included) still often allow it to invade their columns. It is time that medical bacteriologists, especially teachers, abandoned their names-don’t-matter attitude and learned a little of what systematists throughout the world are trying to do to make the name something more than a label. The modern English usage, as exemplified by Topley and Wilson’s Principles of Bacteriology and Immunity, is based on an interim report of a committee of the Society of American Bacteriologists. In America, nomenclature has evolved from the final report of the same committee, the different stages being represented by successive editions of Bergey’s Manual of Determinative Bacteriology. Topley and Wilson’s classification may be described as a conservative application to bacteria of the binomial system of nomenclature. In the first edition most of the gram-negative rod-shaped bacteria, chiefly of intestinal origin, were placed in an unwieldy genus Bacterium, but the latest edition (1946) recognises the separation of the typhoid-food-poisoning group as the genus Salmonella and the dysentery bacilli as
generic name spore-bearing