A general malaria survey of Sarawak and Brunei, two of the territories of British Borneo, is described. Contrary to what was expected in view of the climate and the general conditions, the prevalence of malaria in Sarawak and Brunei proved, on the average, to be low. The coastal areas were found to be practically free from the disease, although epidemics have occurred there in recent years. Malaria was found to be endemic in the hilly and mountainous interior. In fact, topography proved to be an important factor in malaria prevalence, the spleen- and parasite-rates, generally speaking, being higher the more abrupt the country. Differences were also observed in the prevalence among the various racial groups, but these were considered to be due to different habits and customs rather than to race itself.Entomological studies showed that Anopheles leucosphyrus Dönitz was the main malaria vector in the interior of Sarawak, A. barbirostris playing a secondary role. A. leucosphyrus balabacensis had already been recognized as the malaria vector in Brunei.The favourable results of a first field trial of residual insecticides are mentioned and plans for a nation-wide malaria-control programme are briefly outlined.
After two years' use of hexachlorocyclohexane (BHC) as a larvicide in Georgetown, on Penang Island, control of Culex fatigans breeding became unsatisfactory. Two laboratory colonies of fatigans were established, one from Georgetown, and one from Kuala Lumpur where no insecticides had been used; tests were then made to determine the median lethal concentrations (MLC) of BHC, dieldrin, and DDT for the larvae of the two strains. The Georgetown strain was found to have acquired a tenfold resistance to BHC, and also to dieldrin to which it had not been exposed, but it showed no significant increase of resistance to DDT, to which it had also not been exposed. A year later, when both strains had passed through some ten generations in the laboratory without exposure to insecticides, the Georgetown strain was found to have lost much of its resistance to BHC, although the MLC was still twice that of the non-resistant Kuala Lumpur strain.
The author summarizes the information given by 13 governments-Afghanistan, Burma, Ceylon, China, India, Indonesia, Malaya, Netherlands New Guinea, Philippines, Portuguese India, Sarawak, Thailand, and Viet Nam-on their existing and proposed malaria-control programmes in response to a questionnaire prepared by WHO for discussion at the First Asian Malaria Conference, which was held in Bangkok in September 1953.Although in late 1953 nearly 46.5 million of the 271 million people living in malarious regions were protected against the disease, more than 224 million others were still unprotected.It is noted that residual-insecticide spraying-the basis of most campaigns-has significantly reduced spleen- and parasite-rates; that the minor opposition to spraying initially encountered in some places quickly disappeared as the benefits became apparent; that malaria control has resulted in general improvements in public health and has promoted socio-economic development; that anopheline resistance to the insecticides used has not been observed; that ten governments voiced the need for indoctrination of public officials concerning malaria control; and that there is a trend among governments to make financial provision for long-term malaria-control schemes.
A fulminating extension of rabies-which has been enzootic in northern Malaya since 1924-occurred in Kuala Lumpur in April 1952. The outbreak was suppressed by the compulsory mass vaccination of dogs, stringent legislation, and intensive stray-dog destruction. Similar measures are being employed in the current campaign, the aim of which is the complete eradication of the disease.From an average annual incidence of 112 confirmed canine cases prior to 1952-when a total of 198 cases was reported-the incidence fell to 15 cases (all in unvaccinated dogs) for the period January-November 1953, during the last 5(1/2) months of which no case in either animals or man was reported. It is considered that the extensive publicity campaign and strict enforcement of the control measures have contributed measurably to the present improved position.Statistics relating to confirmed cases in dogs previously vaccinated with (a) phenolized 20% brain-tissue suspension vaccine (buffalo origin) and (b) chicken-embryo vaccine (Flury strain) are quoted and their probable significance in favour of the latter under Malayan conditions is discussed. The hypothesis that the development of rabies may, in many instances, have been blocked by the vaccine is advanced.The plan for a pan-Federation compulsory vaccination campaign in 1954, to consolidate the 1952-3 improvements, is outlined.