mostly of young adolescents whereas in 1957 the group was more representative of the population distribution.
229. Stanley Prison. All inmates of Stanley Prison are X-rayed as soon as possible after arrival; those found to be infected with tuber- culosis are assessed and treated by a Medical Officer from the Chest Clinic who visits the prison weekly. Hospital treatment is available on a scale which ensures that any prisoner whose case so requires it can be admitted to hospital. The result of examinations were as follows:
Total number X-rayed
1936
1957
3.036 78
4.649 88
Number of cases of active tuberculosis found
230, School Teachers. Teachers in Government schools are examined annually in the course of the annual X-ray survey of Goverment Servants. Teachers taking up first appointments in private schools have a compulsory pre-registration X-ray of the chest before permission to teach can be given. The Medical Department is the official agency for certification. No details of the total number of teachers examined each year are available but the results of the findings of cases who attended the Chest Clinics for assessment and certification are appended:
Referred to the Chest Clinics Unfit to teach on account of
pulmonary tuberculosis Percentage
1954 288
1955
19.56
1957
348
455
318
36
49
53
76%
10-62 107% 16-6
231, School teachers found unfit to teach are permitted to resume work as soon as it appears that they can do so without prejudice to the health of their pupils. They have complete freedom of choice as to where they have treatment, but they are accorded priority of treatment at the chest clinics and of admission to hospital if this is found to be
necessary.
MALARIA
232. The staff of the Malaria Bureau responsible for the control of malaria in the Colony consisted of one Malariologist, one Assistant Malariologist, two Senior Malaria Inspectors, eleven Malaria Inspectors. one clerk and some 315 temporary monthly or daily rated gangers and labourers. The post of Assistant Malariologist is a newly created one and has only been filled since 25th November, 1957.
233. The population at risk is approximately 2,700,000. When the emoluments of all staff, and expenses on insecticides and equipment arc
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all taken into account, the cost of antimalarial work amounts to approximately forty two cents per head of population per annum. This also includes the cost of control of 'nuisance' mosquitoes in certain areas. 234. In addition to control measures, malacia surveys were undertaken in various parts of the New Territories and field tests carried out to ascertain the effect of various insecticides on mosquito larvac,
235. By arrangement with the Waterworks Office, an additional store was handed over to the Bureau at Deep Water Bay in August 1957 and during December five old Military Block Houses above Lai Chi Kok were acquired as combined stores and coolic lines. These additions have greally facilitated area control work,
236. Control is based mainly on anti-larval measures. Areas in Hong Kong and Kowloon at present under active control consist of the urban areas in which the main bulk of the population is concentrated. In addition, in the New Territories, the Tai Lam Chung Reservoir Site. Rennie's Mill Camp, the Castle Peak Hospital area, the Chi Ma Wan Prison on Lantao Island, and the southern inhabited portion of Cheung Chau Island are similarly protected. For convenience of supervision of the labourers, the control work at Cheung Chau, is the responsibility of the Medical Officer of Health, New Territories, under whose direction is a resident Health Inspector.
237. At Hay Ling Chau Leprosarium the anti-malaria work is under- taken by the staff there and the necessary insecticides are supplied by the Bureau. Regular visits are made by the staff of the Malaria Bureau to ensure the effective continuation of anti-malarial measures on the Island.
238. In order to delay as long as possible the development of resistance of the malaria vectors against chlorinated hydrocarbon insecticides, anti-malaria oil has, since early 1957, been more generally employed as the larvicidal agent. Gummexane Dispersible Powder, the principal larvicide relied upon in previous years, is now used only for areas such as agricultural lands where the application of oil is contra- indicated. Another feature which has come to notice is that Gammexanc Dispersible Powder P520 in the usual dosage has become, in many instances, no longer effective against culicine mosquito breeding, par- ticularly Culex faligans, which frequently breeds in or ocar potential anopheline breeding places.
239. On one occasion during the year, a complaint about a leaf-burn effect on water-spinach due to Gammexanc Dispersible Powder P520
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.