X1000306-1970-71_Part01 — Page 8

are shown in Figure 3. The incidence of measles continued to remain low since the commencement of the anti-measles vaccination campaign in late 1967.

Cholera

FIGURE 1

INCIDENCE OF MAJOR INFECTIOUS DISEASES 1936 – 1970

DIPWTHANIA

CATALOG

POLITANA DEN

TRAE

14. Since the last reported case of cholera in October 1969, Hong Kong remained free from the disease throughout the year under review. The surveillance programme for the disease was continued on a year- round basis. This included routine sampling of nightsoil for cholera vibrio, routine bacteriological investigation of specimens sent to the Medical and Health Department pathology laboratories of cases of gastro-enteritis, as well as the sampling of well water and of food stuffs liable to be involved in the transmission of the vibrio. No positive samples were obtained from these investigations. As in previous years a mass immunization campaign against cholera was started in April and continued into the summer months.

15. In addition to the surveillance programme, other special preven- tive measures, including environmental and food hygiene, were continued and strict quarantine restrictions were maintained in respect of neigh- bouring countries declared infected.

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Amoebiasis

16. This disease continued to occur endemically, being most preva- lent in the overcrowded urban areas. A total of 68 cases were notified. The disease remained predominantly one of adult males.

Bacillary Dysentery

17. This disease showed a further decline in incidence falling from 736 cases in 1969 to 609 cases in 1970. The disease occurs at all ages, but 40.1% of the notifications were in respect of children under the age of 5 years. Shigella flexneri and Shigella sonnei remained the predominant organisms isolated.

18. Transmission of infection among families and in institutions is a feature of the disease and very often a number of symptomless carriers are detected among members of the same family or inmates of the same institution. In all a total of 363 carriers were discovered during investigations of reported cases. All were given appropriate treatment.

Chickenpox

19. This is a very common disease among children; a total of 959 cases were notified, almost all the cases reported being under 15 years of age. The seasonal prevalence of the disease is in winter and spring. and hence the earlier part of the year saw an increase in the number of notifications.

Diphtheria

20. Only 43 cases of the disease were notified during the year, this being the lowest number ever recorded for many years. As a result of annual immunization drives, which have been in progress since 1959, the disease has shown a continuous and steady decline, falling from 2,087 cases in 1959 to 43 cases in 1970. The disease affects largely children, and 48.8% of the cases were under the age of 10 years. The case fatality ratio in 1970 was 9.3%, and death occurred primarily among the unimmunized children. Corynebacterium diph- theria mitis remained the predominant organison isolated in clinical cases.

Enteric Fever

21. The number of cases notified was 438, a decrease of 108 cases over the preceding year. The disease in Hong Kong is generally mild,

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