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25. Virological investigation of the disease is maintained on a routine and year-round basis. Poliomyelitis virus Type I was the predominant causative agent in clinical cases and only I case of Type It and 6 cases of Type III were encountered. A comparatively poor rise in Type I antibody in children following vaccination, prompted a variation in December 1964 in the composition of the trivalent vaccine used (the new formula containing 1097 TCID 50 of Type 1. 10% of Type II and 1055 of Type III compared with the old formula which contained an equal amount. 105 TCID 50, of the three poliovirus types) and the commencement of a programme of administration of Type I vaccine soon after birth. Serological study showed that a singk dose of Type 1 soon after birth was valuable as an adjunct to a later programme of two doses of the trivalent vaccine. This new programme succeeded in provoking a better immunological response to Type I poliovirus in a higher percentage of infants and an equally good response to Type II and Type 111 polioviruses. This method came into general use immediately after the close of the period under review, and it is hoped that its success will be reflected in future epidemiological statistics.

Influenza

26. The notification of influenza is entirely voluntary and hence too great a significance cannot be placed upon the recorded incidence. Virological investigations of throat swabbings and throat washings are continued on a year-round basis. A limited outbreak of influenza was recorded in February March 1966. The causative agent was found to be mainly influenza A2 virus, but a few isolates of influenza B virus were also obtained. Comparative antigenic studies carried out by the World Influenza Centre showed that the Hong Kong influenza A2 strains were more closely related to recently isolated influenza A2 variants than to the original 1957 strain, and that the Hong Kong influenza B strains were very similar to the B/England/5/66 strain.

Tetanus

27. This disease, although not notifiable, is recorded with reasonable accuracy owing to the severity of the symptoms in clinical cases thus bringing this to the notice of the Medical Services. In past years, approximately half the cases reported were newborn whose birth had

not been attended by trained personnel and who had been exposed to various hazards from unsterile materials, particularly the use of a powder containing raw ground ginger root as an umbilical styptic. It is encouraging to record that, in 1965, tetamus neonatorum was respon- sible for only one-third of the recorded cases of the discase and that the infantile mortality from such infection was 0.17 deaths per 1,000 live births as compared with 0.25 deaths per 1,000 in 1964 and 1.2 deaths per 1,000 in 1951.

Viral Hepatitis

28. Notification of this disease is not compulsory. While the figures recorded for the period under review are therefore not strictly com- parable with those of previous years, there was an impression of a rise in the incidence of the discase during the first three months of 1966.

29. Developments in certain other communicable diseases are re- viewed later in this report while the remainder showed little variation during 1965 and hence require no comment.

30.

IIL WORK OF THE HEALTH DIVISION

AREA HEAITE WORK

Much of the work of the area Health Officers, apart from their duties with the Urban Services Department in the maintenance of satis- factory standards in environmental sanitation and food hygiene, has been recounted in the preceding paragraphs on Epidemiology. Such work included not only the field investigations into the major com- municable diseases but also the co-ordination of the activities of teams of inoculators participating in prophylactic immunization drives. Four such campaigns were staged during the year and reference has already been made to three, namely cholera, poliomyelitis and diphtheria. The fourth, promoting smallpox vaccination, was held soon after Chinese New Year in February 1966, traditionally an auspicious time for receiv- ing this immunization. The increasing importance of Hong Kong in international travel by sea and air and the prevalence of smallpox in nearby countries underline the need to maintain a high level of com- munity protection against the disease.

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