A malarial survey

About the time when the Kapar drainage scheme was sanctioned, namely in 1904, the pioneers of the rubber plantation industry, who had started about 1898 in a small way in the coast districts of Selangor, began to obtain some tangible reward from their enterprise. Coming from Ceylon after the coffee debacle, when that prosperous industry had been almost completely wiped out of the island within a few months by disease, they had planted Liberian coffee in the State of Selangor in the F.M.S. By 1901, however, this coffee had ceased to pay. It could not compete with Brazilian coffee; and the price of the local product dropped in the course of two or three years from $44 to $12 and $15 a picul,8 at which figure it did not pay.

Casting round for some alternative crop, a few men interplanted their coffee with rubber about 1898. From the first the young trees throve so well and grew so sturdily that the coffee was soon overshadowed and was cut out. By 1904 the new industry was firmly established. Planters were confident in its ultimate success. Large areas of land for its cultivation were taken up, and labour began to come in freely from India.

If the history of other tropical enterprises was to be taken as a guide, the opening up of the land, especially when done with imported labour, was likely to produce virulent outbreaks of malaria, and to be costly in lives, both of Europeans and Asiatics. My hospital returns showed how severely the existing estates were suffering already, and I determined to study the matter in more detail.

From one point of view this great agricultural development presented a unique opportunity for the study of tropical malaria. From small areas like Klang and Port Swettenham, malaria had almost been completely eradicated by the draining of swamps, and the clearing of jungle; and from Kuala Selangor malaria, I gathered the idea that the disease could be controlled over wider areas. The great agricultural development, which was to be assisted by the Kapar drainage scheme, was now to put the idea to the test. It was, indeed, from my point of view a great experiment in the prevention of malaria; that it was to be on a scale infinitely larger than any experiment, which would have been undertaken as such, was no disadvantage; while the fact that it would be carried out by planters, on practical and commercial lines, added to its fascination.

Arriving in the middle of the epidemic of malaria in the coast districts in 1901, I commenced work at once on the control of the disease, but I always felt that I was handicapped by the absence of information which would have been available had the records of previous years been more complete. In the new developments, I was in a much more favourable position. I was witnessing the “birth,” so to speak, of many new estates. The opportunity was afforded me of examining and recording the conditions which existed on them from their earliest days, and, as it has happened, I have since been able to watch their development for many years. Further, by 1904 I had acquired a considerable knowledge of what malaria was, and how it affected a community—a knowledge which I did not possess in 1901. Between 1901 and 1903 I had devoted considerable time to microscopic work on the blood of patients admitted to hospital, and to the clinical aspects of malaria.

It soon became evident that many patients were really suffering from malaria, who when admitted, complained of symptoms other than pyrexia [fever]. Some of these observations were published in 1905 in a paper entitled “Some Clinical Aspects of Quartan Malaria” [11]. In it I showed that in 18.18% of the cases pyrexia was absent for periods averaging 6.4 days; and in 18.18% of the cases the rise in temperature was at so much longer intervals as to lead to little, if any, importance being attached to it by the patient. A considerable experience of labour convinces me that 1 or 2% of coolies working on malarious estates have pyrexia of which they are unconscious; and which they deny, even when the thermometer shows a temperature of 102°F [37^∘C]. The same will often be seen in hospital. I was led to the conclusion that while there might be much pyrexia and few, if any, parasites to be found in the peripheral blood during the first few days of the illness, the later stages might show large numbers of parasites and no pyrexia, as immunity was becoming established. It appeared to me that sufferers from malaria might be divided into two classes, those with pyrexia and those without, the latter being neither fewer in number nor less in importance. And the more I see of malaria the more I find to support this conclusion. It supplied an explanation of the extraordinary fall in the number of deaths registered in Klang in 1902 as due to diseases other than malaria; and the observations on coolies on large doses of quinine and apparently in good health referred to in Table 12.7 further bears it out.

It is sometimes said that the native registers everything as malarial fever, and that the returns grossly exaggerate the amount of the disease. This may be so where there is little malaria. I am convinced, however, that where there is any considerable amount of malaria the error is entirely the other way, and that many deaths from malaria are recorded as due to its complications instead of to the disease to which they are really due. In confirmation of this view, there is the great fall in the number of deaths recorded as due to diseases other than malaria when malaria was reduced in Klang,as shown in Table 4.4.

The result of my microscopic work in hospital convinced me of the enormous amount of malaria on the estates of the district; and, in 1904, I determined to carry out as complete a survey as my official work would permit.

Choosing the most unhealthy months of the year, November and December, I visited a number of estates in different parts of the district, and made examinations of the fresh blood of the children. The work was laborious, but the specimens were taken by an assistant; and I examined about eight to ten an hour. Out of the 298 children under the age of ten examined in 1904, no fewer than 101, or 33.89%, were infected. During the same months, 1905, 1906, and 1907, either blood or spleen examinations were made, and in 1909 and the early part of January 1910, examinations of the children on every estate of Klang and Kuala Langat districts were made either by Dr. Macaulay or myself, and blood examinations were also made by Dr. Macaulay on some estates. The species and breeding places of the anopheline have also been determined.

These observations have been continued by my medical officers and myself year by year until the present date (1919), as the subsequent pages will show. It is probably rare for one man to have the opportunity of making so long a series of observations under the conditions which obtain here. If so, they must have an added interest, even if they are not a unique record.