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ANNEX (E)
REPORT OF THE MALARIA BUREAU.
Although there was again a marked increase in the population of Hong Kong in 1917, the number of autifications of malaria again fell. GOS uses were notified with 224 leuths as against 2,422 cases with 720 dentls in 1946. These are necurred in the transient Chinese population and were not contracted in Hong Kong, From the European and Portuguese civilian population who are the criterion of the efficiency of the anti-mularia work, only one case of malaria was reported on the Island, and one it Kowloon for the whole year.
Staff.
The staff of the Bureau is made up of one Malariologist, three Senior Inspectors, 4 Inspectors and 4 Probationer Inspectors, Mr. Wong Tak Keung joined the stuff as a Probationer Inspector ou let Jaunary, The labour force enosiate of 9 Overseers (thanger 1), 18" Foremen (Ganger TT1, 42 Head Coolies and 260 Coolies.
Field Work.
3. In spite of prolonged and bouvy rainfall in the moutha of June, July and August, which resulted in the opening up of many new snopheline breeding places and widespread damage. control proved effective. Rough Training of streams, stone drainage, ditching, subsoil draining and oiling wem the methods used. To addition to maintaining the work already curried out, the controlled areas of Shauson Hill, Sbek O, Kai Tak, Kowloon City, Cheung Sha Wan, Shum Shui Po and Lai Chi Kok wers improved by 8,500 yards of additional training, 150 yards of permanent drainage was carried out by the P.W.D. at Telegraph Bay and existing anti-malarial drainage was repaired at MI. Parker, Tyemuo and Sookunpo. A great improvement in anti- nosquito work resulted in the employment by the Railway, Taikoo Docks, the Kowloon Docks Co. and the Dairy Farm of foremen who have been given a training at the Maluria Bureau in modern methods of control. These staff while puid by the above companies are under the supervision of the Bureau. In the area outside the control of the Bureau, namely the New Territories, residual DDT spraying was carried on throughout the year at all Government Offices, Quarters, and Police Stations. In addition, Aplichun Taland, Green Tslumul, One Tree Island, Middle Island. Tweed Island and Shek O Wan Tslands off Hong Kong which were found to be breeding Aedes Togoi giving rise to a mosquito nuisance, were visited monthly by launch and the breeding places eliminated.
Mosquito Nuisances.
4. Mosquito muisances were investigated on behalf of the Urban Council at Kowloon City, Kowloon Tong, Kai Tuk, Lai Chi Kok, Hung Hom, Yaumati, Tsim Sha Tsui, Eastern District, Central District, Upper Level, Repulse Bay and Aberdeon.
5.
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Malarial Surveys.
Malarial Surveya were undertaken on behalf of the Army
at Sun Wai, Tai Tam and Clear Water Bay: the Navy at Stone Cutters Island, and the P.W.D. at Tai Lami Valley.
Laboratory.
6. The majority of the equipment ordered from the Crown Agents has still not yet arrived, and it has been impossible to start our photographic section. In addition to the routine larval and adult mosquito examination the results of which are appended, a den consus was undertaken for the Health Department. Some 3,000 Aeas were examined confirming that I. cheopin as în previous years had an index of 96.37%. Entomological examina- Lions were undertaken in beetle and By infestation of food at Government Stores, and moths causing a nuisance in the New Territorios. Of entomological interest was the finding of
A. minimus in large open spaces of water, namely the reservoira, where it was breeding in the grassy edges of the shallower portions. Cutting of the grass in one instance, and lowering of the water level in another, resulted in their disappearance. This is the first time both in the Colony and us far as can be ascertained from the literature anywhere else, that A. minimus has been recorded in much situations.
Insecticides. DDT, and Gammexane.
are
7. These bave little use in the anti-malarial programme en the Island and Kowloon where larval control is maintained. In the New Territories, however, where anti-larval measures impracticable, spraying both with DDT and Gammexane has, es has heen found in other parts of the world, brought the morning catch of anopbelines to practically zero. Unfortunately there was no corresponding drop in the blood parasite rate of the village children examined. This has been found to be the case in other parts of the world, and the question of village spraying needs further investigation before it is undertaken on a large scale. In the New Territories the use of Gammexane Smoke combined with tuosquito proofing has proved excellent. A well mosquito proofed European style house situated within a 100 yards of the malarious village of Kam Tain was one toonthly treated over the year with Gommexana Smoke and the writer occupied it at weekenda and further for a continuous period of 14 days in the height of the malarious season, Although the screening was black with muaquitnes on the outside-it was impossible to catch one in the house. No nets were used and none of the inmates suffered from malaria. The servants, whose quarters were unnetted and only ten yards away, suffered heavily. Similar results were obtained in Police Stations which were screened. The combina- tion of screening and Gammexane Smoke would appear to be the method of choice for protecting any non-immune population in an uncontrolled area. Gammexane concentrate (1 in 20 Kerosene) has proved an excellent larvicido for the Muscidae. It is superior to DDT.