were not detected, but it was believed that such virus was prevalent in the community in view of an increase in the number of clinical polio- myelitis in the year under review. In 1967 the number of poliomyelitis cases notified was 5, increasing to 15 in 1968 and 16 in 1969.
Influenza
28. The surveillance programme for influenza is continued on a year- round basis. A number of general out-patient clinics are designated as influenza surveillance centres, which report regularly the number of influenza-like illness seen at these clinics. The Virus Laboratory con- tinues to function as a World Health Organization National Influenza Centre and virological investigations of throat swabbings and throat washings are carried out routinely on samples taken from influenza-like
CELSES.
99.
During the year the disease caused sporadic outbreaks. In- creased incidences were recorded in March and August 1970 but no epidemic was observed. Between January and September 1970 the predominant influenza virus was type A2, but the strains showed no antigenic deviation from the A2/Hong Kong/68 variant which caused an epidemic of influenza in July 1968. After September influenza virus type B was predominant. One of the two antigenic strains of the influenza type B virus was closely related to B/Czechoslovakia/28/70, and the other strain to B/Rome/1/67.
Teranus
30.
This disease, although not notifiable, is recorded with reason- able accuracy owing to the severity of the symptoms, requiring hospitalization of clinical cases. In past years approximately half the cases reported were in those new-born whose birth had not been attended by trained personnel and who had been exposed to various hazards from unsterile materials. In 1970 tetanus neonatorum was responsible for only 13.6% of the recorded cases, and infant mortality from such infection fell from 1.2 deaths per 1,000 in 1951 to 0.103 deaths in 1970.
Viral Hepatitis
31. Notification of this disease is on a voluntary basis. A compari- son between the number of notifications received and the number of
to
viral hepatitis cases discharged from Government and Government- assisted hospitals showed that notifications for this disease are far from complete. A better and more complete reporting and investigation of the disease was under review at the end of the year, and it was hoped that such improvement would result in a better understanding of the true incidence of the disease in Hong Kong and its epidemiology.
32. Developments in certain other communicable diseases are reviewed later in this report; the remainder showed little variation during 1970 and hence require no comment.
III. WORK OF THE HEALTH DIVISION (Tables 20-45)
AREA HEALTH WORK
33. Much of the work of the area Health Officers, apart from their duties with the Urban Services Department in the maintenance of satisfactory standards of 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 communi- cable diseases but also the co-ordination of the activities of teams of inoculators participating in prophylactic immunization drives. Five such drives were staged during the year and reference has already been made to four, namely, cholera, poliomyelitis, measles and diphtheria (and in the latter campaign the vaccine used combined immunization against diphtheria with active anti-tetanus prophylaxis). The fifth, promoting smallpox vaccination, was held in February 1971. 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 community protection against the disease.
TUBERCULOSIS (Tables 20-26)
34. As stated previously, tuberculosis is the major health problem of Hong Kong. The policy for control of the disease has been to protect. by vaccination with B.C.G., the new-born, who are particularly vulner- able to the fulminating forms of the disease, and the primary school
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