Malaria
31. The incidence of malaria during recent years showed a notable reduction, the discase being restricted mainly to the uncontrolled areas of the New Territories. Of the 11 cases reported during the year eight were imported cases, while in the remaining 3 two were recurrent cases and one was due to blood transfusion.
Measles
32. As revealed in Figure 4, measles in Hong Kong has shown a distinct biennial pattern, with exacerbation of the disease every alternate winter and spring. The last epidemic occurred in the winter months of 1966-67 and reached its peak in the first three months of 1967. Thereafter the incidence of the disease began to decline and the disease has since remained at a low ebb.
FIGURE 4
MONTHLY MEASLES NOTIFICATIONS & DEATHS JANUARY 1960 - MARCH 1970
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отнение АНАНИЕ
33. At the end of December 1967, measles vaccine was made avail- able at all Government Maternal and Child Health Centres to children aged between 6 and 48 months, the reason for the selection of this age group being that the disease in Hong Kong affects predominantly children under the age of 4 years, and that in this age group there is a
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high mortality associated with the disease, the mortality being due mainly to complications, particularly bronchopneumonia, developing as a result of delay in seeking medical attention. In the summer of 1968 the vaccine was also made available to the public through mobile teams visiting resettlement estates. tcncment areas, New Territories villages, and other areas. At the end of 1968 a total of 83,107 children had been vaccinated and, although coverage was little more than 50% of all those infants and children in the 6 months to 4 years age group likely not to have had measles and to be susceptible to it. the outbreak of measles expected in the winter of 1968-69 did not occur. The measles vaccination drive is now on a year-round basis, the vaccine being available all the time at Government Maternal and Child Health Centres.
Poliomyelitis
34. Sixteen cases of poliomyelitis were reported during the year, and 15 of them were confirmed by laboratory investigation. 13 cases being type 1 and 2 cases being type 3 poliovirus infection. The success in the control of the disease has been due to the continuing vaccination programme, consisting of giving one dose of Type 1 polio-vaccine, soon after birth, followed by 2 doses of 'balanced' trivalent vaccine at three and five months of age. Approximately 74% of infants received one dose of Type I polio-vaccine soon after birth and 67% of children received two doses of the trivalent vaccine at Maternal and Child Health Centres. A general campaign is mounted annually in an attempt to immunize the remainder.
35. Virological investigation of the disease is maintained on a routine and year-round basis. A poliomyelitis faccal survey in normal children aged under 5 years was carried out in June. The result showed the excretor rate of 'wild' type of poliovirus was about 0.3%, which was in agreement with the low incidence of clinical infection. Influenza
36. The notification of influenza is entirely voluntary. The Virus Laboratory continued to function as a World Health Organization National Influenza Centre and virological investigations of throat swabbings and throat washings are continued on a year-round basis.
37. After the major outbreak of infiuenza in July 1968, the causative strain of influenza virus named as A2/HK/68 was absent from the local community for some time. Between February and September 1969 influenza virus type B was found prevalent in the community, causing
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