ENG-1961 — Page 177

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HEALTH

child contacts with BCG. The main difficulty encountered is the unwillingness of many contacts to return for further examination after a year because they neither see nor feel any indication of the disease. A further problem is the resettlement of cured patients in suitable employment, but some limited progress is now being made in this direction.

Malaria is a notifiable disease, but the majority of the 812 cases reported during 1961 were from unprotected areas, pre- dominantly from the Sai Kung district on the eastern shores of the New Territories and from the boat population based on that area. None of the few cases appearing in the urban areas could be traced to infection contracted locally. The important carriers of malaria are A. minimus found breeding in certain hill streams, seepages and irrigation ditches leading to rice cultivation and A. jeyporiensis var. candidiensis which breeds in rice cultivation, fallow rice fields, pools in rice stubble and water flowing through grass. Other anopheline species found in the Colony play little or no part in malaria transmission. Malaria control in the urban areas is based chiefly on anti-larval measures consisting of training and clean-weeding of streams, ditching and oiling. Anti- malaria oil continues to be employed as the main larvicide, although Gammexane Dispersible Powder and Diazinon are also used on a limited scale in areas where the application of oil is not suitable. These anti-larval operations against anopheline breeding afford protection to over 2 million people living within the urban areas of Hong Kong, Kowloon and New Kowloon and in certain circumscribed zones in the New Territories. In the remainder of the New Territories, control by anti-larval measures is not at present practicable. The alternative is control by chemoprophylaxis, a measure requiring the co-operation of the population for complete success. An experiment in chemopro- phylaxis carried out in two villages last year was initially promising, but later proved to be only partially successful due to lack of co-operation.

The endemicity of malaria varies, as was proved by malario- metric indices obtained from a survey carried out during the year in children between 2-9 years of age in 14 villages in the New Territories. Spleen and parasite rates ranged from zero to 40.2% and from zero to 20% respectively. Throughout the year blood