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administered and, although giving good results, are believed to have caused the appearance of erythema nodosum leprosum in some cases. Epidemiological control is based on investigation of contacts, follow-up of defaulters from treatment, and vaccination of child contacts with BCG. The main difficulty is that many contacts are unwilling to return for examination after a year because they neither see nor feel any sign of disease. Resettlement of cured patients in suitable employment is another problem.
Malaria. Although the entire population of Hong Kong is potentially at risk of malarial infection, continuous anti-larval operations against anopheline breeding give protection to nearly two-and-a-half million people living within the urban areas of Hong Kong Island, Kowloon and New Kowloon and in certain circumscribed zones in the New Territories. In the remainder of the New Territories, where the wet cultivation of rice is practised, control is not yet possible either by anti-larval or by anti-adult measures, and the continuing influx of large numbers of infected persons into these areas as a result of the traffic between China and the New Territories makes surveillance impractical as a quarantine measure.
Unfortunately, a small pilot experiment in control by chemo- prophylaxis, involving weekly distribution of paludrine in two villages in the New Territories, had to be discontinued due to dwindling of the necessary co-operation from the public. Results, however, were encouraging as no case of fresh infection was reported in either of the villages throughout the period of the experiment nor for some time afterwards.
Malaria is a notifiable disease and over 90% of the 833 cases reported during 1960 were from the unprotected areas, chiefly from the Sai Kung district on the eastern shores of the Colony and from the boat population. None of the few cases appearing in the urban areas could be traced to an infection contracted locally and in all except two there was strong presumptive evi- dence that the infection had in fact been contracted outside the protected zones. Of the parasites identified 95% were P. vivax, 4.5% P. falciparum and 0.5% P. malariae.
The marked rise in the number of cases of malaria reported during 1960 can be attributed, at least partly, to a survey designed
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