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HEALTH
extending from Kwai Chung, in the west, to Lei Yue Mun in the east. In addition, Cheung Chau Island and Rennie's Mill Village, in the New Territories, are similarly protected. Larvicidal oil continues to be employed as the main larvicide, but malathion, diazinon and gamma-BHC were used on a limited scale in areas where the application of oil was not suitable. These anti-larval operations against anopheline breeding afford protection. None of the few cases appearing in the urban areas during the year could be attributed to breakdown of these control measures. In the greater part of the New Territories where the background is essentially rural, the adoption of anti-malarial mosquito measures described above is not feasible at present and screening of buildings, use of mosquito nets and chemoprophylaxis constitute the main protection against malaria. All anti-mosquito measures for the prevention of malaria are carried out by the pest control section of the Urban Services Department. Clinical aspects of malaria control such as malaria surveys and chemotherapy are the respon- sibility of the Medical and Health Department.
Diphtheria continued to occur mainly among children under 10 years of age. An immunization campaign has been in progress since 1959, interrupted only by the need for anti-poliomyelitis, cholera and other prophylactic, mass inoculation campaigns. House- to-house visits are conducted in resettlement estates and other crowded areas, and teams of inoculators visit schools and squatters. Every effort is made to inform parents of the disease and of facilities available for the protection of their children and, as a result, there has been a steady and sustained decline in the incidence of the disease, with only 226 cases recorded in 1967, representing 10.83 per cent of the 1959 incidence. The case fatality ratio was 7.96 per cent in 1967. Most deaths occurred in non-immunized children who showed advanced laryngeal or pulmonary complications due to delay in seeking proper medical attention. As from August 1967 purified toxoid, aluminium phosphate precipitated, was replaced by combined diphtheria and tetanus vaccine for use in the continu- ing mass campaign.
Typhoid fever incidence showed a slight seasonal increase during August and September. The disease in Hong Kong is generally mild and is frequently associated with neglect in personal and