Cost of operation of the Bureau
192. The entire Colony population is at risk of the infection but approximately 2.367.000 persons are now under protection by anti-Jarval methods. For the year, the cost of the control operations, including action against nuisance mosquitoes in certain areas, was 37 cents (about five pence half penny) per head. This takes into account the emoluments of all staff and the expenditure on anti-malaria oll, insecticides and equipment.
Malaria incidence
193, Notification of malaria was made compulsory for the first time in the Colony in September 1945. The enforcement was discontinued in May 1948, but since June 1950 has been reintroduced.
194. Since 1950 the reduction in malaria mortality has been striking as may be seen from the following figures:
Year
19.50
1951
1952
1953
1954
1955
L
1956
1957
1958
1959
៧ ។ .
668
TABLE 14
Coses notified Deaths
$52
89
756
33
1,305
46
46
85#
16
431
4
LAL
496
447
659
442
1
195. Just over 90% of all cases notified during 1959 were from out- side the urban protected areas, and of these 72.6% came from the Sai Kung district; 27.1% of the Sai Kung notifications were from the boat population, the remainder being scattered amongst 43 small villages in the district. Of the blood parasites identified, 89.1% were P. vivax, 10.2% P. falciparum, 0.5% P. malariae, and 0.2% mixed infection of P. vivax and falciparum. All cases notified from the protected urban areas were fully investigated and not one could be proved to have contracted the infection in the protected zones.
196. There was one death recorded as due to malaria and again, as in the previous year, the victim had been the subject of repeated blood transfusions, this time for a malignant condition of the blood.
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Malaria surveys
197. Two malaria surveys were carried out, one in the urban pro- tected areas and the other in the border zone in the north of the New Territories between Lo Wu and Sha Tau Kok. The former survey was amongst children between 2 and 14 years of age and was carried out in co-operation with the School Health and Maternal & Child Health Services. Between April and October 1959, 1.744 children aged two to five years were examined; the spleen rate was zero. From April to June 1959, 6,676 school children aged five to fourteen years wore also examined and the number with palpable spleens was 18 or 0.27%. In addition 4,033 blood smears were taken from infants under one year of age attending urban Maternal & Child Health centres. All smears were cross checked at the Government Institute of Pathology and all were reported negative for malaria.
198.
In the border areas 907 children between the ages of two and ten years were investigated in eleven villages of whom 1 or 1.1% had palpable spleens. There were no smears positive for malaria in 1,005 blood smears taken from children under 10 years of age.
199. At present, another survey of the incidence of malarial in- fection in children under 10 years of age in the New Territories is in progress. Blood slides are being taken by the medical staff from all febrile children under 10 attending dispensaries in the New Territories and are being examined at the Government Institute of Pathology. An endeavour will then be made to trace and treat all positive cases thus revealed. The survey is expected to give valuable information as to the prevalence of malaria parasites in the blood of children of this age group and at the same time expose at least some of the cases in which the diagnosis which might have been missed without blood examination. At the same time, as more and more cases are being treated, the reservoir of infection, it is hoped, will diminish.
Laboratory
200. The Bureau laboratory continued to carry out the routine identification and dissection of mosquitoes and the staining and exami- nation of blood smears collected during the surveys. Field tests were conducted of the efficacy of insecticides and the susceptibility of anophe- lines to insecticides. Information on tests of insecticide resistance in adult mosquitoes was forwarded to the World Health Organization.
47