Some Pages from the History of the Prevention of Malaria."

Glasgow Medical Journal New (7th) Series February, 1935 Vol. V No. II

ORIGINAL ARTICLES

SOME PAGES FROM THE HISTOEY OF THE PREVENTION OF MALARIA.*

By Sir MALCOLM WATSON, M.D., C.M., D.P.H., Hon. LL.D.Glasg., Hon. F.R.F.P.S.Glasg., Diplomatist (Honoris Causa) of King Edward VII College of Medicine, Singapore.

Introduction.

Gentlemen?When your President and Council honoured me by an invitation to deliver the Finlayson Memorial Lecture, they suggested that an historical account of malaria and malaria control would he appropriate to the occasion. That invitation I accepted with pleasure for a number of reasons. It gave me an opportunity of paying a tribute to one to whom I have often listened and to one whose name and person were familiar to a whole generation of Glasgow medical students as a teacher. Yet he himself never ceased to be a student of medicine; the shelves of your library are enriched by his work as an historian. For many years Finlayson's Clinical Manual was one of my cherished posses- sions, an ever-present aid in time of need when I was isolated in the tropics, and that old well-thumbed volume would have an honoured place on my book shelves to-day but for a desire of white ants to digest its contents.

* Being the Finlavson Memorial Lecture delivered before the "Royal Faculty of Physicians and Surgeons, Glasgow, on 29th November, 1931. yoL. cxxui. no. n. 49 Sir Malcolm Watson

And yet another reason was that it gave me another opportunity of meeting old friends, and of acknowledging my debt to the great city in which I was born, and to the great Medical School in which I was trained. If I have succeeded in any degree, that success has to be attributed to my good fortune " " in sitting under men like .Bower, Buchanan, MacLeod, Gairdner, Macewen, Coats, Middleton and Hawthorne, and two who are present to-day?Barclay Ness, a past President, and Munro Kerr, your President?to name but a few of the teachers of the Glasgow Medical School. A third reason was that those who saw the early stages of the prevention of malaria and have direct personal knowledge of it are becoming fewer in number. Manson, Ross, Gorgas and Simpson have crossed the bourn. Those who remain are very senior, if not in the sere and yellow leaf. What we saw and thought is, perhaps, worth recording, because it was a period of great activity in tropical medicine; indeed one of the great eras in medicine, wThen one discovery thundered on the heels of another. In the sixteenth century a spirit of high adventure filled the veins of Portuguese, Spaniard, English and Dutch alike, and led to geographical discoveries such as the world had never seen before. Late in the nineteenth century a similar spirit infused the medical men of many races, and the discoveries of Koch of Germany, Pasteur of France, Lister, Manson and Ross of Britain, and Reed of America opened a new era in medical thought; so that men could go forth with a new light and new confidence both to cure disease and to prevent it. It seemed to me that, having spent so much of my life in tropical lands, and especially in the study of malaria and its prevention, this would be a suitable opportunity to attempt to trace briefly the history of the prevention of malaria since Ross made his epoch-making discovery on '20th August, 1897, and completed our knowledge of the life cycle of the malaria parasite in the mosquito on 9th July of the following year. Ross expected that his discovery would lead to measures for the prevention of malaria by mosquito reduction being taken at once throughout the world. But although the scientific world was deeply interested, and although his discovery fired men to research in tropical medicine in which the important part played by insects in the spread of disease came to be 50 History of Malaria Prevention fully realized, little practical use of Boss' discovery was made, to his unconcealed and bitter disappointment. In 1910 Ross published his Prevention of Malaria. It contains contributions from many lands on the work that had been done in the previous ten years. As an historical record it is of great interest; but it is likewise tragic evidence of the failure of the world as a whole to use the discovery. After Lister made his great discovery there was a time-lag of nearly a generation before antiseptic and aseptic surgery was properly understood, and came into general use. History has repeated herself by a similar lag in the prevention of malaria. To-day I propose first to survey the history of prevention in various lands, in order to discover, if possible, the reason for progress in some countries and delay in others, and then more briefly to scan the future. Of course, this lecture makes no pretence to be a complete history of all that has been done in the past thirty-six years. What I have attempted has been to record something of what has come within my own personal knowledge and experience. It is, as its title indicates, only " Some Pages from the History of the Prevention of Malaria."

The Fit*st Successful Anti-malarial Work in the British Empire.

The work in Malaya, begun in 1901, was described by Boss as the first successful anti-malarial work in the British was so it Empire. In that year the malaria intense that threatened the existence of two small towns, on the coast of the State of Selangor, no farther from the equator than Chester is from London. People of all races walked in fear of it. Business was suspended, and religious ceremonies and processions were organized in an appeal to higher powers for help. One of the towns was a new port for the Federated Malay States. The High Commissioner actually sent a tele- I was instrumental in gram ordering its closure, but having that order withdrawn. Although the work of eradicating malaria seemed well nigh hopeless on account of the high temperature, the heavy rainfall (100 in. a year), the extensive the work was swamps and the luxuriant tropical vegetation, was so successful1 that in a few months life in the towns proceeding smoothly, the port was not closed, and the number 51 Sir Malcolm Watson of deaths among 3,500 people fell from 582 in 1901 to 144 in 190*2, and later to a mere fraction of that number,* as the following figures show :?

Deaths in the Towns of Klang and Port Swettenham.

Other Year. Fever. Diseases. Total.

1900, ... 259 215 474

1901, ... 368 214 582

1902, ... 59 85 144

1903, ... 46 69 115

1904, ... 48 74 122

1905, ... 45 68 113

I wish to draw particular attention to the decrease in the deaths from other diseases.2 It was entirely unexpected, and indeed its significance would not have been understood but for my work in the hospital, which showed that large numbers of patients were admitted complaining of diseases such as nephritis, abscess, convulsions, diarrhcea and dysentery, but who had malarial parasites in their blood. They were suffer- ing from malaria, from the complications of malaria, or from infections by organisms which had been able to gain an entrance from the lowered vitality of the host as a result of malaria. This was a discovery of the very highest importance in public health in the tropics, and it has thrown a light on malaria in many lands. I would also like to emphasize, for reasons which will appear later, that the discovery was made as the direct result of practical work, or, as I might call it, a large-scale experiment in the control of malaria in these two towns. Nothing but the combination of such an experiment with hospital work could have established so clearly this knowledge. There is one other lesson I would like to emphasize. It is that the success of this work was due to the careful pre- paration of plans. Accurate microscopical work was done in

* In 1901 the number of cases of malaria treated in the hospital, indoor and a " out-patients, among population of 3,500,, was 1,772. For the year ]933 the number of cases of malaria infected in the Sanitary Board area of and Port Swettenham one Klang (now administrative area) was 117 among a . . population of 34,920. . The spleen rate of school children in the town area is 2.9 per cent among 1,561 children." 3 52 History of Malaria Prevention the hospital; accurate statistics of the disease in hospital, and among Government officers, were compiled; an entomological survey showing the distribution of anopheles was made; and our engineers prepared the plans carefully. Being myself physician, health officer and entomologist, there was perfect co-operation with the engineer. But not less important was the strong support given to the schemes by the District Officer, Mr. H. B. Ellerton, and the acting Harbour Master, Mr. C. W. Harrison; indeed, it would only be doing justice to these two members of the Malayan Civil Service to say that they were the first to propose these anti-malarial schemes, and that as early as February, 1901. There was nothing half-hearted about this work. We were out to get success, if success were to be got. Money was spent freely in the light of our knowledge at that time. I say, bluntly, we deserved success. Fortune favoured the bold, but we had greatness thrust upon us, for our success was far beyond our expectations. Year by year men have come to study what was done in these two places, and carry the lesson to distant lands. The Government of Malaya would have reason to be proud of its work for the prevention of malaria in 1901 had that stood alone : the people of Malaya were to earn lasting fame from their greater achievements in the years that followed.

Our Mistakes.

It was inevitable that we should make mistakes in our early work. Certainly we did make them, not only in the early work, but at all stages in our later work. These mistakes led sometimes to excessive expenditure of money, sometimes to lessened efficiency, and sometimes even to complete failure in our anti-malarial efforts. Fortunately in our first work in Malaya our mistakes did not lead to failure, or even lessen our success, but they cost money?and a good deal of money?for which I take a very full share of responsibility. For example, at Port Swettenham the drainage system discharged at mean sea level, instead of some feet below that level; but fortunately there was still ample fall to drain the land. Secondly, the inverts of the main drains were made of cast concrete. I was afraid that earth drains discharging at a lower level would permit the 53 Sir Malcolm Watson

" " breeding of anopheles. Thirdly, a large amount of filling was used, especially in Ivlang, which a more perfect drainage system would have avoided. But while the engineers were frequently changed owing to the exigencies of the service, I remained in Ivlang for twenty- eight years; from the first I took an interest in the engineering side of the work, recognized our mistakes, and gradually had them corrected, in some places actually laying out and super- vising the construction of the drains in more effective lines of drainage; and I have often thought that this actual executive work was the best teacher I could have had. These early experiences have proved invaluable to myself mistakes were used to demonstrate what to and others. My?/ avoid. Knowledge of many kinds was being picked up, and here I would like to acknowledge my indebtedness to the planters of the district for many valuable lessons, as well as to the engineers among whom, throughout my whole life, I have found allies and friends.

The Malaria of the Coastal Lands.

You have all heard of the great work of the reclamation of the Roman Campagna which Signor Mussolini has begun. For two thousand years malaria has been a scourge in Italy ;4 in certain of the coastal areas all efforts to stamp out the disease failed, but now Mussolini is making an effort which there is 110 reason to doubt will succeed if it is resolutely carried to a completion, as you may be sine it will be. But while you have all heard of this, few of you have probably realized how the Governments of Malaya have been draining deeper and blacker swamps and boldly fighting graver malaria for a quarter of a century before the Italians began the schemes in the Agio Romano. The Roman Campagna is a small area, compared with the thousands of square miles of alluvial coastal plains of Malaya which sink into the mangrove swamps of the Straits of Malacca and the China Sea. At the end of last century devastating malaria and blackwater fever swept these coastal lands.5 In some villages whole families were destroyed within a few weeks, and the development of the land was greatly hindered. Stretching both north and south from the town of Klang, in which I was stationed, 54 History of Malaria Prevention for hundreds of miles was an alluvial plain, in which there was not a village but was stricken by malaria. A formidable problem; but a careful study of the hospital statistics, of the reports of District Officers and engineers, and of the land itself led me to believe that a drainage scheme such as had given so brilliant a success in the towns of Klang and Port Swettenham might lead to a similar result on a larger scale.6 Drainage had for centuries been known as a remedy, if not always as a certain remedy, for malaria. As an experiment it was worth while. It would, however, have been foolish from every point of view to attempt an experiment on a very large scale, but about 50 square miles seemed sufficiently large to test the methods. Once again our plans were carefully laid. Thanks to the wisdom of the Malayan Government, an Institute for Medical Research had been started in 1900 with the cordial approval of Mr, Joseph Chamberlain, then Secretary of State for the Colonies, who not only gave his support to the Schools of Tropical Medicine in London and Liverpool, but envisaged their being linked up with research institutes in various parts of the tropics. These were his words :?7 " During my term of office I have addressed to the Governors of the tropical Colonies various circular despatches on medical and sanitary subjects, more especially in connexion with the investigation of malaria and the training of medical officers in the treatment and prevention of tropical diseases. " In the present despatch I wish to summarise the steps which have been taken and the results which have followed, and also to make some suggestions as regards the future. . . . " The above is an outline of what has been attempted in the direction of improving health and sanitation in the tropical Colonies and Protectorates, and the Governments concerned will, I think, realise that the contributions which they have given have been applied to objects second to none in importance and public usefulness. But it is clear that the work cannot stand still, and as long as those who can speak with the authority of science are confident that by human effort the rate of mortality from malaria and other tropical diseases can be greatly reduced and the strength and efficiency of European residents in unhealthy climates can be sensibly increased, so 55 Sir Malcolm Watson long, in 11 ly opinion, ought funds to be forthcoming for carrying on what lias been so well begun." One of the first fruits of the Institute in Malaya was a 8 study of the mosquitoes by Dr. G. F. Leicester, working in close co-operation with Mr. Theobald of the Natural History Museum of London. From Dr. Leicester I learned what he knew about the local anopheles in the year 1903, and I would like to acknowledge my great indebtedness to him. Compared with what we know to-day, Leicester's knowledge was, of course, not great; bat he gave us a solid foundation on which we could build. When Government, as a result of a consultation on the spot between leading planters, the Resident General, F.M.S., Sir William Teacher, the British Resident, Mr. Douglas Campbell, the Director of the Institute of Medical Research (C. W. Daniels), the Director of Public Works, and various minor officials including myself, approved the expenditure of $110,000 (about i>13,000) on the construction of 37 miles of main drains, some 20 feet wide, to drain an area of about 50 square miles, the entomological and engineering knowledge which I had acquired in the previous years was to prove of the highest value in my joint capacities of District Surgeon, local Health Officer, and private Medical Officer to the estates situated in the area. Part of this area was under European cultivation, mainly with rubber and coffee; and a considerable part con- sisted of small estates and small holdings owned by Malays, Javanese and Chinese, who grew coffee, coconuts, bananas and fruit trees.

Carey Island.

Here I do not propose to give details of the results; they are recorded in both the first (1911) and second (1920) editions of my Prevention of Malaria in the Federated Malay States. It is sufficient to say that the results were no less striking than those obtained in the first work at Klang and Port Swettenham in 1901. But perhaps in this city of Glasgow I might single out for comment the results obtained on the estates of the Jugra Land and Carey Limited, a company whose registered office is not half a mile away. When the estates were started I had already acquired the knowledge of how to prevent malaria on land such as they 56 History of Malaria Prevention were planting; and except for a small outbreak of 19 cases in 1920 there have never been more than isolated cases of the disease, almost invariably contracted off the estates which arc on an island, access to and departure from which is under supervision and control. The estates are within a few miles of Port Swettenham, and on land of the same nature. In a recent paper,3 Dr. Barclay Barrowman, a Glasgow mail, and my successor at Klang, writes?" Carey Island is situated in the delta of the Klang and Langat Rivers. The land is low lying clay soil with high ground water, in fact it is naturally a fresh water swamp surrounded by salt water swamps, conditions which in the tropics are notorious for producing the most appalling malaria. . . . On Carey Island, with a population of over 5,000 scattered over an area of 18,000 acres of 26 square miles, there has been one child with enlarged spleen during the past five years, and she had arrived on the estate with the spleen already enlarged. The infection rate among the total population for the past five years has been under one-tenth per cent per annum, while the birth-rate, calculated in relation to the adult female population, was 200 per mille per annum, and the Infantile Mortality rate 136 per mille. . . . On Carey Island there is rapidly growing up a locally born labour force?18 per cent of the present population was born on the estate. There are over 1,500 healthy happy children, among whom the sick day rate last year was no more than 04 per cent." Dr. Barclay Barrowman then goes on to describe how malaria " " carried by two deadly species of mosquitoes has been controlled from the opening of the estate in 1906 and says? " This combination of measures is so successful and so unobtrusive that the whole population goes about its daily work doing nothing it would not do elsewhere, and unconscious that but for the control in force the Island would be one of the death traps of the tropics."

Large Scale Experiments.

When the Government approved of the Ivapar drainage scheme as a sanitary measure we had in fact begun a series of experiments, which both in space and time are, I believe, finique in the history of tropical medicine. We began with 57 Sir Malcolm Watson a comparatively small area?about 50 square miles, but before many years passed I had records of hundreds of square miles, for land was being opened up rapidly. What gave the experiments their value was the manner in which a single factor would be changed, while others remained unchanged, in rectangular areas of land, the size of which was exactly known, and accurately recorded on maps. Sometimes we deliberately moved the population from one site to another; sometimes we removed the anopheles factor by draining and felling the jungle in which they lived; sometimes the change was accidental, as when something had been done unknown to me, a something which I discovered only when I found that the incidence of malaria had changed. But whatever the change, none proved an exception to the rule. There is something else unique about the experiments begun in 1904. For twenty-eight years I lived in an area, observing and recording admissions to hospital, spleen rates, deaths and other, things; this and my ssuccessor, Dr. Barclay Barrowman, has continued wTork with enthusiasm and success. By 1909 we had advanced our scientific knowledge to the position that, of something like a dozen species of anopheles to be found in the coastal plains, one alone, A. iimbrosus, was proved of practical importance. Its home and breeding place was the great black swamp of the primeval jungle on the flat coastal plain, and the inner portion of the mangrove forest. I proved that although the mosquito could fly more than half a mile, it carried malaria effectively for only half a mile. We could destroy it with absolute certainty by draining the swamps in which it lived ; and by selecting sites over half a mile from the jungle, we could be almost as safe from malaria as if we were in Glasgow. By correlating the spleen rates with the distance from the breeding places of the dangerous species, and also correlating the death-rates with the spleen rates, it was possible to predict with almost mathematical precision the amount of malaria on the and any spot in thousands of square miles of peninsula, in the death-rate of any population that might live there. Or other words we had a sound and simple rule for the prevention which of malaria, which any man could understand and apply, has stood the test of nearly a third of a century. I want to emphasize that our success has come from the knowledge acquired not in the hospital alone, nor in the laboratory alone, 58 History of Malaria Prevention

nor in the field alone, but by co-ordinated work in all three, and it led to discoveries in clinical medicine, protozoology, ecology and epidemiology of fundamental importance in the prevention of disease.9 It was as if an explorer in a strange land had chanced on a hidden treasure of priceless gems; for these discoveries were to prove invaluable to Malaya and other lands. In the hand of governments, medical men, planters, engineers and others they have saved hundreds of thousands of pounds, and prevented an incalculable amount of sickness, misery and death. In my little laboratory I was breeding mosquitoes, discovering new species of mosquitoes, recognizing structures that enabled ine to construct a key for the identification of the larva* of certain species of anopheles, a matter of great practical importance. In the field I was studying the biology of the insects, the reactions of the larvae of different species to different qualities of water and to the seasons of the year, the biting habits of the flies and the part they played, and, not less important, did not play, in the transmission of malaria. As medical officer, I saw and treated the sick in hospital; made post-mortem examinations on all possible occasions; noted carefully what the nature and distribution of disease was; studied the very different seasonal waves of malaria caused by different species of anopheles; selected sites for new buildings, advised the removal of old ones to healthy sites, or recommended the destruction of jungle and drainage of swamps often in large blocks, as seemed after discussion with the planter the proper measure in each case. I was in fact searching out the secrets of nature by observation and experiment. But they were experiments 011 the grand scale where miles and years took the place of millimetres and minutes; and the lives of men, women, and children of white, brown, yellow, and black races and not animals were at stake. Sometimes it was exasperating that, when malaria was incomparably the greatest medical and economic problem of the district, my studies should suffer constant interruption from official duties and the work of a large practice; for I was the sole European medical officer and practitioner in the three coast districts, an area 100 miles long, in which in these early years travelling was done more often 011 foot or bicycle, under an equatorial sun or in mud and torrential rain, than by train, launch or motor car. Yet, looking back, I realize more fully 59 Sir Malcolm Watson that work in the hospitals; at the quarantine station; on cholera, smallpox and tuberculosis; in designing hospitals aud houses, was not the least part of my education. Without this " my knowledge would have been of one subject alone; and he one branch of his art is like a bird with one who knows only?/ wing.'' Nor was the isolation of these years, when I saw a fellow- worker usually no more than once a month, without compensa- tion. It gave just that sort of opportunity for quiet reflection and work on which Darwin and Wallace built monumental achievements. I say these things, for in my journeyings I often meet keen men isolated in the tropics, burdened with the charge of enormous tracts of land, whose feelings were once my own, and who need some word of cheer and encouragement. The beginning and early stages of some of these experiments and their results are reported in some detail in the first edition of my Prevention of Malaria in the Federated Malay States, published in 1911; and later stages are reported in the second " edition, 19*21, the subtitle of which is a Report of Twenty Years' Progress." Since 19*21 little has been published, except short accounts of the more striking achievements; for the work of the prevention of malaria in Malaya has now become a part of the routine sanitation of the land. I can conceive of no other way in which this knowledge of flat land malaria could have been acquired and still more put on so solid a foundation in so short a time. Even so, all this took some years. By 190G, I had already learned much, but happily it was for practical purposes completed in 1909, when I realized that we were confronted with a new malarial problem of?I use the words deliberately?appalling gravity and magnitude.

The Great Swamps of Malaya.

If you wished to travel in a straight line from the sea to the main mountain ranges at the part of the Malay Peninsula where I lived, you would land in the mangrove forest zone. At low tide you would have to wade across anything up to a quarter of a mile of deep mud before you reached the mangrove trees. I do not propose to attempt to describe this strange 60 History of Malaria Prevention forest?that would be quite beyond my pen. But I will try to give you some indication of it. The foundation is a foul- smelling mud in which you sink up to the knees at least. The trees are not content with springing from the ground in one straight pole; they throw down aerial roots, which become flying buttresses. These strange trees form seeds like small brown pears, to each of which is attached, while still in the air, a root a foot or more long and nearly an inch thick, like a thin cucumber. When ripe, the seed drops off, and the root is driven by its weight deep into the mangrove mud and so is securely planted. Among the roots of the mangrove move the salt or brackish waters of the sea, rising perhaps three or four feet up the stems of the trees during high tide, and leaving the mud wet, clammy and stinking at low tide. The inhabitants of this strange region are many. Great eagles and fish hawks sail in the sky. Monkeys chatter and little green paraquets are in flocks in the tree tops. Fish with large eyes come out of the creeks at low tide, stare at you, and if satisfied hop over the mud on their pectoral fins. Crabs of vivid hues build hills and dig holes. Poisonous snakes abound. Wild pigs hunt in the mangrove for fruits and roots, and in turn are hunted by tigers, who only too often develop a taste for the wood-cutters of the forest. Crocodiles are by no means scarce. In the stomach of one I found a dog licence and a monkey's skull intact, but they too do not hesitate to attack man, even when he is in a canoe with several companions.* Both day and night the mosquitoes are so abundant that you are constantly attacked by dozens of these pests. But in the evening and during the night the little fireflies, with their myriad vibrating lights, make an entrancing sight, when viewed from a boat or a moving motor car. I do not deny

* The injuries inflicted by a crocodile are severe. The beast seizes its victim below the middle of the thigh, tears the muscle off the femur, and removes the limb at the knee-joint or leaves it hanging by the tendons. It next seizes him by the upper arm, and inflicts similar injuries in that limb. Amputation in the upper third of the arm and l,eg is required. After a few operations I found it better not to close the flaps for forty-eight hours, as they invariably became septic, the pus having the same smell as the contents of " " the crocodile's stomach. A case of crocodile bite invariably made its presence known in a ward by its smell. In spite of cold, wet, shock, and a journey (in the old days) in a bullock cart of several hours, some of these cases survived.

61 Sir Malcolm Watson

that the mangrove forest has its merits, and seen at a distance is a thing of beauty, but personally I now prefer it at a distance. In this zone, recognized rightly as a stronghold of deadly tropical malaria, we had mastered the disease, as the histories of Port Swettenham and Carey Island have demonstrated beyond question. Passing inland, we come to another forest of a totally different nature. In place of the slowly moving, muddy, brackish or salt water of the mangrove forest, we have a dark brown peaty practically stagnant swamp, often with a pH of 5. The trees are entirely different from those of the mangrove, of an average height of perhaps 80 feet, with monsters that might run to well over P20 feet. Here nature has specialized in the making of spines?and acquired great skill in her efforts. They may be great or small, fine or stout. Those of the beautiful Neibong palm are 6 inches long, and strong enough to pierce anything but the thickest leather. And here are two simple rules for travelling in a Malayan forest. Don't travel close to the man in front of you. Don't put out your hands to save yourself when you slip and fall. Long climbing plants, whose thickness varies from that of a man's thigh to a fine whip-cord armed with rows of recurved hooks, stretch from tree to tree, from branch to branch ;at the Wembley Exhibition one was shown over 500 feet long. Some climb up to the sunshine and then sink back into the gloom of the depths of the forest and form an entanglement that can only be penetrated by a continuous use of the knife. On the branches of the trees, especially near to the tree tops, are masses of orchids and other aeroids. Unlike the mangrove forest in almost every respect, this fresh water forest has this in common. It is difficult to get through; indeed, even more difficult I think, and in many places impassable owing to the depth of the swamp. It stretches for hundreds of miles along the coasts of the Malay Peninsula. The haunt of mosquitoes and of malaria, it presented at first sight as formidable a malaria problem as one could imagine. Yet we had overcome it, and could make our plans for the prevention of malaria with confidence of practically 100 per cent success.

62 History of Malaria Prevention

Anopheles Mactjlatijs.

The visitor resumes his journey inland. After traversing miles of deep slippery swamp the traveller is glad to set his foot on solid land. He hopes he has left the stagnant swamps and their malarial mosquitoes behind him. But it is not to be, for although the land is hilly there are swamps in the valleys, and they contain the malaria carrier of the plains, A. umbrosiis. And if the valleys are drained and the forests cleared, a procedure which drove malaria from the coastal . plains, that same happy result does not follow in this hill land. On the contrary, malaria seems, if possible, to be aggravated. This is due to the arrival of an anopheles which did not live in the original jungle. This mosquito I had met for the first time in 1901, and described its larva in running " water. In a clear pond, with a considerable current, and with no obvious vegetable growth, a large number were found 10 at Jugra. The sides were clean. This was a well in use." It was really a widened part of a hill stream. Little did I realize then what this capacity of living in moving water was to mean. My more intense study of mosquitoes in ravines began about 1904. Some 13 species of anopheles lived in the hills. Which species predominated, depended as I gradually learned on the condition of the swamp in the bottom of the valley. These conditions varied greatly. There might be the deep shade of virgin jungle; or the partial shade of felled jungle; or the partial shade of secondary jungle; grass might have grown when the jungle was felled; silt washed from the hills might have killed or partly killed the grass or jungle, so that gases of vegetable decomposition bubbled up as you waded in the swamp. The valley might have been drained, and the drains entirely free from grass and other vegetation, or partly free or choked with vegetation. Each one of these conditions and other conditions favoured some species, and was so prejudicial to others as to drive them out. In addition, man, his excreta, his works, the refuse of his industry, were influences by no means negligible; while on the top of all, meteorological and seasonal influences were of profound importance to the various species, causing them to appear and disappear in a way that added to this amazing puzzle, 63 Sir Malcolm Watson

For four years all the time I had to spare from my official duties and a large private practice was devoted to this and allied problems, and it was not until 1909 that I felt I had a grasp of this hill problem. My observations were announced in my Presidential Address to the Malaya Branch of the British Medical Association in February, 1910; a summary appeared in Ross' Prevention of Malaria (1910); and in greater detail in my Prevention of Malaria in the Federated Malay States, published by the Liverpool School of Tropical Medicine in 1911. But it was not enough to report the results of researches on the biology of various species of anopheles, or the conclusion . that this hill land, whether under jungle or free from jungle, would remain permanently under the influence of devastating malaria. What the country required was some new method of preventing the disease. To this I now turned my attention, and fortunately my previous nine years' work on the prevention of malaria was to prove invaluable. Klang and Port Swettenham might be described as an apprenticeship. During the Kapar Drainage Scheme I was a journeyman. Now I was to be tested for promotion. During these years I had acquired a considerable understanding of the engineering of drainage. Not less important, I had a deep conviction that this deadly A. maeulatus could be exterminated if appropriate measures were adopted. So I devised a system of subsoil drainage of valleys, calculated to withstand the powerful erosive action of torrential tropical storm water scouring its way down valleys cleared of jungle, and such that every spring, seepage and ]xx)l of water would be dried up a few hours after every fall of rain. The system proved a success, and although I did not fully realize it at the time, contained much that was original.11 12 The publication of my book in 1911 created, I think I may say, rather more than a mild sensation in Malaya. The death- rate on the rubber estates at that time was causing the gravest anxiety both to the planters, to the Governments of Malaya, to the Government of India from which so much of our labour was drawn, and to the Colonial Office. A Colonial Office Committee13 on Tropical Labour in 1910 had commented on the high death-rate of estate labourers in Malaya, but reached the wrong conclusion that the cause of the high death-rate was dysentery, and the cure better water supplies, Death- 64 History of Malaria Prevention rates of over *200 per 1,000 per annum on estates were by no means uncommon,11 and the high figure of 185 per 1,000 for all the estates in Negri Sembilan, one of the States of the Federation, in 1911, was suspected as not indicating the whole truth, since labourers when ill frequently left the estates to go to, and often die in, the towns. In Kuala Lumpur, the capital of the Federated Malay States, malaria had attacked many of the best built and most beautifully situated houses, occupied by the highest Government officials, nor was any part of the town entirely free from the pestilence. In Singapore, the capital of the Straits Settlement, a city then of over a quarter of a million of people, malaria, which had swept away large numbers of the people every year, raised the death-rate to 5091 for the whole year and to the high figure of 858 in the month of June, 1911.

Seafield Estate.

The honour of first utilizing the new researches fell to Seafield Estate. At that time the health was most unsatis- factory, and in 1910 the directors, on the advice of Mr. Norman Grieve, a member of the board, and Mr. H. R. Quartley, the manager of the estate, sanctioned expenditure for an experiment with subsoil drainage. I need hardly say that the most careful preliminary examination of the whole problem had been made. Dr. Stanton, of the Institute for Medical Research,* was kind enough to confirm my incrimination of A. maculatus as the carrier of malaria on the estate, and " of its larvae attached to small stones in a stream of considerable volume and current, free from grass and other vegetation."15 Mr. Bach, M.I.C.E., had already made a survey of the ravines, and prepared plans and estimates which complied with my requirements. Although the first area drained had a protective zone of only about a quarter of a mile in breadth, the improvement in the health of the labour force was so great that the directors immediately decided to extend the area and to protect the whole population on the estate by this new subsoil drainage system. The whole area was completed at the end of 1915. It is impossible to give full details here, but the following table taken from the

* Now Sir Thomas Stanton, Chief Medical Adviser to the Colonial Office. VOL. CXXIII. NO. II, 65 E Sir Malcolm Watson

Bulletin of the Rubber Growers' Association16 will give some idea of the success of the scheme :?

Malaria Cases. Average No. treated Total Percentage labour No. admitted as number of labour Year. force. to hospital, out-patients. treated. force treated. 1014, 658 815 5,370 6,185 939 1915, 804 900 3,235 4,137 513 191G, 811 933 1,558 2,491 312 1917, 770 719 546 1,265 162 1918, 639 718 315 1,063 149 1919, 825 614 10 624 75 1920, 916 1,236 1,256 132 1921, 780 609 609 77 1922, 620 369 369 53 1923, 577 56 56 9 1924, 557 6 6 1-08

The cost capital of the subsoil drainage, 1911-1918, was $68,243, about ^8,000, but this was handsomely repaid by an increase in the amount of crop and a lowering of the cost of production. In 1920 I wrote?" However we look at the matter, it would appear that the whole cost of the subsoil drainage was repaid and probably much more than repaid in the and that year 1919; the gain in previous years, while less in amount, can have been no mean sum. In other words, apart from the of human life and ' saving conservation of bark,' the cost of the subsoil drainage has probably been repaid several times over in the past five years."

Singapore.

This city was next off the mark. In 1911 the Health Officer, the late Dr. W. R. C. Middleton, reviewed the whole question of malaria in the city in an able report,17 and subsequently, at his suggestion, and on the invitation of the Anti-malarial of Committee, which the Colonial Secretary was chairman, I visited Singapore and made recommendations for dealing with the most malarial district. Before drainage work was started, Dr. Middleton, Dr. Finlayson, the bacteriologist who was carrying out the entomological work, and Mr. B. Ball, the Municipal Engineer, visited Klang and Port Swettenham, and were shown the work we had done and the mistakes we had made. In my report18 to the Anti-malarial Committee 66 History of Malaria Prevention

I drew special attention to the mistakes that had been made in the past, in order to prevent their repetition. The work in Singapore was admirably executed, and led to a rapid and permanent fall in the spleen-rates and death-rates. A few years later the care of the malaria work was placed in charge of Dr. P. S. Hunter, assistant Health Officer, and I had nothing but praise for his work when I paid my periodic visits of inspection. In 1924 Dr. Hunter became Health Officer of Singapore, and has continued the work, of which it is impossible to speak too highly. Singapore is now a city of nearly half a million people. Malaria has long ceased to be the scourge it was up till 1911, when the Health Officer reported that malaria was the most prevalent of all diseases in Singapore and increasing in prevalence and severity. The great malaria wave of the months of May, June and July has faded to a comparatively slight rise, due mainly to imported cases. Within the municipality in 1932 there were 41-25 miles of concrete channels, 72 63 miles of subsoil pipes, and over 300 miles of earth ditches ; 18,682 gallons of anti-malarial mixture were used. The result on the death-rate is seen in the following table :?

City of Singapore. Death-Rates from all Causes, 1892-1933.

Year. Year. 1892, 31-67 1913, .... 3412 1893, 35-48 1914 .... 3411 1894, 31-77 1915, .... 2739 1895, 4009 1916 , 2926 1896, 47-62 1917, ...? 3575 1897, 40-87 1918 (influenza), . 42?8 1898, 34-75 1919, .... 3*45 1899, 34-70 1920, ...? 35-51 1900, 41-58 1921, .... 33,99 1901, 45-62 1922, .... 3186 1902, 5123 1923, 269 1903, 47-25 1924, .... 2706 1904, 44-62 1925 2821 1905, 4&75 1926, . 32 04 1906, 3795 1927, . 1907, 46-46 1928, . 2844 1908, 46-79 1929 2621 1909, 38-56 1930, . 2773 1910, 42-89 1931, . 25-2 1911, 50-91 1932, ; S^12 1912, 4201 1933, .... 1966 67 Sir Malcolm Watson

As elsewhere, the removal of malaria has been followed by lowered death-rates from other diseases, and larger numbers of children have survived. Had the sex proportions and ages of the population and the death-rates between 191*2 and 193*2 remained the same as between 189*2 and 1911, upwards of 100,000 additional deaths would have been recorded. While other public health measures have contributed to the lowering of the death-rates, the chief measure was the anti-malarial work, which reduced the great annual malarial wave.

Malaria Advisory Board, F.M.S. In the Federated Malay States the Government next took up the work, and in November, 1911, the Malaria Advisory Board began work wrhich was to prove invaluable to the wThole of Malaya. The President of the Board was the head of the Government, Mr. (later Sir) E. L. Brockman. The other members were Dr. Sanson, P.M.O., F.M.S.; J. H. M. Rob son, Esq., a member of the Federal Council; Dr. A. T. Stanton,* of the Institute for Medical Research ; F. D. Evans, Esq.,t Assistant Engineer, P.W.D. ; H. R. Quartley, Esq., manager of the Seafield Estate, and myself. At the first meeting I stressed the importance of Government setting its own house in order, in order to set an example to others. At that time Kuala Lumpur, the capital of the Federated Malay States, was teeming with malaria, as a result of a series of measures which had increased rather than decreased the disease, a story graphically described in chapter XXVI of my Prevention of Malaria bv Dr. A. R. Wellington. + The Board agreed to this, the work was admirably carried out by Mr. Evans, who had been assistant engineer in Klang and was conversant with my work, researches and plans. Space does not permit me to give the results; it must suffice to say that the work was a success, with a notable reduction in the malarial and general death-rates of the town. The other point I stressed at the first meeting, and throughout my period of service on the Board, was that the Board

* Now Sir Thomas Stanton. f Now Deputy Director, Public Works Department, Nigeria. X Now Dr. Wellington, C.M.G., Director of Medical and Sanitary Services, Hong Kong. 68 History of Malaria Prevention should not sanction expenditure unless the officer applying for the money had presented a properly prepared scheme, showing the incidence of malaria, the identification of the breeding places of the anopheles, and details of the engineering plans which he recommended. Where the latter were incomplete the Board's engineer gave the necessary assistance. The evolution of this Advisory Board is of sufficient interest to be recorded. As the head of the Government was the President of the Board, the Board's decisions became effective without further reference or delay. Ultimately a sub-committee, con- sisting of Dr. Wellington, Senior Health Officer, F.M.S. ; Mr. Evans, and myself, considered all schemes before they were presented to the Board. Further researches 011 anopheles were carried out by Dr. Stanton.19 The Board became, in fact, from the date of its first meeting, a department of Govern- ment, co-ordinating both practical and scientific work, and responsible for the expenditure of a considerable amount of money. For the year 19*26, when Sir Ronald Boss visited Malaya, the expenditure 011 malaria by the F.M.S. Govern- ment was i}104,400. Waste of money was reduced to a minimum, and the success of the work was a great stimulus to private efforts.

REFERENCES.

" 1 Watson, M., 1930, The Saving of Port Swettenliam," Jouru. Trop. Med., 1st December, 1930. 2 " Watson, M., 1905, The Effect of Drainage and other Measures on the Malaria of Klang, F.M.S., Second Report," Journ. Trop. Med., April, 1905.

" 3 Barrowman, B., 1934, The Prevention of Malaria in Children," Report of the Association Internationale de Pediatrie Preventive, Geneva, September, 1934. 4 Celli, A., 1925, Storia delta Malaria nelV Agro Romano. 5 Medical Report of the State of Selangor for the Year 1899. " 6 Watson, M., 1904, Drainage of Country Roads," Selangor Government Gazette, 1904. 7 Chamberlain, J., Secretary of State for the Colonies, :28th May, 1903, Circular to Governors on the Investigation of Malaria and the Training of Medical Officers in the Treatment and Prevention of Troical Diseases." 8 Studies from the Institute for Medical Research, F.M.S., 1908, vol. iii. 9 Watson, M., In addition to the papers already mentioned or to be mentioned, I wrote or collected the data in these years for the following 61) History of Malaria Prevention

papers :?44 A Note 011 the Parasites of a Case of Malignant Malaria with Discussions 011 the Development of the Crescent," Journ. Trop. 44 Med,, 15th July, 1903; Drainage of Country Roads," Selangor 44 Government Gazette, 1904; Memorandum on Insanitary Houses in 44 Selangor," Selangor Government Gazette, July, 1904; Some Clinical Features of Quartan Malaria," Journ. of the Malaya Branch of the 44 B.M.J., Jan., 1904 (reprinted in Ind. Med. Gaz., 1905); Notes of Cases of Salpingitis, Pyosalpinx and Pelvic Abcesses," Malayan Medical 44 Journal, 1904; A Case of Dengue Fever with Hyperpyrexia," paper 44 read to Malaya Branch of B.M.A.; Studies from the, Institute for 44 Medical Research," Culicidas. of Malaya, 1908, vol. iii, p. 38; Rare Nervous Symptoms Produced by Malaria," Brit. Med. Journ., October, 44 " 1908 ; A New Anopheline from the F.M.S. Annals of Trop. Med., 44 Liverpool, July, 1910; Studies in the Parasitology of Malaria in the Federated Malay States between 1900-1912," Indian Journal of Medical 44 Research, April, 1932, vol. xix, No. 4; A Case of Dengue Fever with Hyperpyrexia," Malayan Medical Journal, 1932. 10 Studies from the Institute for Medical Research, F.M.S., 1901, vol. 1. p. 87. 11 Annual Medical Report of the F.M.S., 1911. 12 Watson, M., Prevention of Malaria in the Federated Malay States, second edition, p. 134. 13 Colonial Office Committee on Emigration from India to the Crown Colonics and Protectorates, 1910. 44 11 F.M.S. Government Gazette, Report on Indian Emigration for the year 1911." 15 Watson, M., Prevention of Malaria, p. 137. 44 10 Watson, M., Malaria in the Malay Peninsula," Bulletin of the Rubber Growers' Association, 1925. 17 Middleton, W. R. C., Report on Malaria, Singapore Municipality, 1911. 18 Watson, M., Notes on Malarial Conditions in Teloli Blanga District, Singa- pore, published by Singapore Municipality. 44 19 Stanton, A. T., Anopheles of Malaya," Bulletin Entl. Research, 1912-15.

(To be continued.)