was received. The matter was thoroughly investigated with the co- operation of the Agriculture. Fisheries and Forestry Department and, after repeated tests, it was found that a suspension of the powder at a lower concentration of 1:120 would obviate the phytotoxic effect.
240. In the protected areas of Kowloon and Hong Kong, numerous check catches and surveys were done by the Bureau and, except in one or two instances, no anophelines, either larvae or adults, were found. Vector mosquitoes however abound on the borders of the controlled areas and, given a favourable opportunity, can increase rapidly at any time. It needs no emphasis that constant vigilance is necessary.
241. In the laboratory, in addition to the routine work of identi- fication and dissection of mosquito specimens collected in the field and the staining and examination of blood smears, special field tests on the efficacy of various insecticides were conducted.
242. The total number of malaria cases notified for 1957 was 447 compared with 496 in 1956. The Table at Appendix 4 gives the source of these notifications, whether from the protected areas or not, the type of infection and the nature of the attack, fresh or recurrent.
243. Analysis of the twenty four 'fresh' cases notified from "protected areas' revealed that eighteen of these were either apparently contracted outside protected areas or were recurrences of a previous malaria infection, 96-2% of notifications were from Government clinics and hospitals.
244. It is worthy of note that approximately 93% of the cases notified originated outside protected areas, and that the Sai Kung area was responsible for 71% of all reported cases. Nearly 88% of the infections were due to plasmodium vivax.
245. No death from malaria was recorded in 1957, compared with four in the preceding year,
246. In the New Territories, malaria surveys were continued at Ho Chung, Wo Mei, Nam Wai, Kai Ham, Pak Kong Au, Tai Po Tsai. Tai Mong Tsai, Tso Wo Hang. Tseng Lan Shue, Ngong Wo, Shan Liu, Yim Tin Tsai, Wong Yi Chau, Lan Nai Wan, and Shek Pik Villages. During these surveys, spleen examinations of children of 2 to 10 years of age and blood examinations of children up to 10 years of age were performed. Altogether & total of 544 children presented themselves for spleen examination and 591 for blood examination. The spleen rate varied from 0 to 20% and the parasite rate from 0 to 69% among the individual
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villages. In another reconnaisance carried out at the two small villages of Ma Yau Tong (North-east of Kung Tong) and Shan Shek Wan (on Lantão Island), respectively, the spleen rate was 0% in the former and 57% in the latter out of ten and seven children examined respectively.
247. The above result confirms the previous observation that the degree of malaria endemicity varies in different parts of the New Territories, though on the whole it cannot be considered to be severe at the moment. Up to now no overall anti-malaria programme has been cxecuted there, although some control work is being undertaken in the selected areas mentioned earlier,
248. At Shek Pik, where the construction of a new reservoir is contemplated, preliminary surveys were undertaken with a view to estimating the cost of the anti-malaria work considered to be necessary. Proposals regarding the extent and cost of control have been submitted to Government.
SOCIAL HYGIENE
249. The Social Hygiene Service is concerned with Venereal Diseases and Leprosy. The Social Hygiene Specialist is also the Government Consultant in Dermatology. The staff establishment remained unchanged from the previous year.
250. The death of Dr. S. C. Fong in August 1957 is recorded with deep regret. Dr. Fong was one of the most active and experienced mem- bers of this sub-department and the loss is a severe one.
Venereal Diseases
251. Four out-patient clinics for males and nine for females were maintained for the diagnosis and treatment of venereal disease. The number of new patients attending all clinics showed a fall of about 2% compared to 1956.
252. The table below shows the numbers of new and total attend- ances at clinics for the last five years.
Yeor
1953 ...
1954 ...
1955 1956
1957
TABLE ZI
New Patients
Total Attendancer
37,392
213,091
36,652
223,031
34.853
203,701
32,400
180,148
31.393
193,674
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