143. In the rural areas there is no overall vector control programme except in the limited areas previously mentioned. The scattered popula- tion, the widespread wet cultivation and the unprotected contiguous borders render unfeasible the adoption in these areas of either anti- larval or anti-adult measures. Therefore, paludrine prophylaxis continues as the main line of defence against malaria for disciplined groups stationed in the New Territories.
144. The cost of the control measures during the year under review was thirty eight cents per head of population living in the protected
areas.
Incidence of Malaria
145. Malaria is a notifiable disease, and the returns for the past five years are set out in Table 17.
Year
1936
1957
1958
1959 1960
TABLE IT
MALARIA 1956-60
Cases Notified
Deaths
496
+
447
659
442
$33
146. The marked increase in notifications during 1960 is due to a survey designed to give an accurate picture of the prevalence and dis- tribution of malaria in the New Territories.
147. The survey, which was carried out in conjunction with the Principal Medical Officer of Health. New Territories, and the Gover- ment Institute of Pathology, was designed to take a blood smear from every child under 10 years of age with pyrexia attending at a clinic in the New Territories and to subsequently examine such smears for the presence of malaria parasites. At times it was impossible to complete the investigation on every child attending the travelling and floating clinics, but the number so omitted was small; there was no selection of cases. At the same time, all notified cases of malaria were analysed and grouped into areas comparable with those in which the blood smears had been taken. The results are detailed in Table 18.
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Tai Po
TABLE 18
MALARIA IN NEW TEARCTORIES 1960
2
KEMANA
1960
7
Fishie
3
+
Populario#
%% of total
*******
N.T. capra
Incidence Der 2.900
J
Podpre
blo
JOTEDTA
M Fazrives da Percentage
ber 1.000
at Turhal
population
147,307 13
1.7
0.09
S
0.5
0,05
Yuen Long- Tsuen Wan
104,632
0.3
0.02
0
99.905
#
1.0
0.09
021
0.02
14,427 380
50
**
162
43
Sai Kung Boate South Lantau
13
5,376
14.5
20.5
7,690 210
13.5
27
63
2.3
9.2
Ixthods
40.336
39
5.0
0.7
34
2.8
0.85
Total
409,679 763
100
P
369
Sai Kung
148. The experience of previous years is repeated in that the large majority of cases came from the area surrounding the small town of Sai Kung on the east coast. However, South Lantau has now appeared as an important endemic focus and, although the increase in the number of cases reported in that area can be attributed to the posting of a full- time medical officer to the waterworks project and to the presence of a large number of workers who have not developed tolerance to the symptoms of malaria, there is still a relatively high incidence in the villagers of the district, as shown by the smear survey.
149. It will be seen that in every district surveyed there is close agreement between the incidence of malaria and its latent frequency in children, suggesting that reporting of cases may be more complete than might have been supposed. Nearly all cases occur in the littoral rather than in inland districts; the possibility that the vector is carried by boats must obviously be taken into account but is not supported by the evidence available, particularly when the absence of cases of malaria în other islands is considered. Further investigations are in progress but, meantime, treatment is given whenever possible to all cases with a positive blood smear.
150. Of the few cases of malaria reported from the areas of the Colony covered by control operations, none could be traced to an infection contracted locally and in all cases except two there was strong presumptive evidence that the infection had in fact been contracted outside the protected zones. Of the parasites identified, 95% were P. vivax, 4.5% P. falciparum and 0.5% P. malariae.
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