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(d) INVESTIGATIONS AS TO PREVALENCE OF MALARIA IN CERTAIN AREAS.
These were continued at Kowloon Tong, others were commenced at Shek O, Lai Chi Kok Gaol, and Shing Mun Dam. Areas previously dealt with were again investigated with the object of obtaining certain information, namely the Ravine above Pokfulam Reservoir, Reservoir, Wong Chuk Hang locality between Aberdeen and Shouson Hill, the surroundings of the site for the new Government Civil Hospital, and a Ravine at Repulse Bay. Minor investigations were made at Barker Road where breeding places of A. maculatus were found; at Ngau Tau Kok where spleen rates were taken and a larval survey done; at Deep Water Bay where the blood of eleven servants at the Golf Club was examined and no malaria parasites were found, although hill streams are close by, however mosquito nets were in use and quinine was being issued.
Kowloon Tong.
The area investigated at Kowloon Tong extended half a mile outwards from the periphery of this Garden City and required as much time as would be needed for several ordinary surveys, owing to its extent. Kowloon Tong is approximately rectangular in shape, its long border being perpendicular to a range of hills which is parallel to and adjacent to a short border. Several streams flow down from these hills, and the majority soon finds their way into trained channels. Numerous larvae of A. maculatus and A. minimus have been found in these streams. Whilst little evidence of the prevalence of malaria was forthcoming from the portion remote from the hills, this was not the case in the neighbourhood of the hills. A spleen rate of 3.45% was obtained amongst the children of the cultivators in the neighbourhood, these, as a rule, resided at some distance from the hills as the narrow heads of the valleys do not afford much scope for growing crops. For blood examinations servants were considered to be the best material owing to their being less careful, as a rule, as to the use of mosquito nets and attention to adequate treatment of malaria when contracted. Thick blood films were taken from 187 servants living within quarter mile from the hill foot, 14 of these contained malarial parasites or 7.49%. Out of 160 films taken from those living half mile and more from the hill foot, only 1 was found positive or 0.63%. In the blood films of 103 servants living between quarter mile and half mile from the hill foot, 5 infections were found or 4.85%.
Shek O.
Owing to complaints of malaria received, visits were paid to Shek O towards the end of the year and arrangements made for the making of a map of the area concerned. Larval surveys have been done and spleen rates taken of the village children
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