MM 106
Calculated on an average strength of 2336 the admission rate for the year was 20.55 per 1000. Amongst the Indian troops there were seventy-five infections of which fifteen were in 1st quarter, eighteen in 2nd Quarter, twenty-five in 3rd Quarter, and seventeen in 4th Quarter. These work out for the year as 50.44 per thousand on an average strength of 1487.
Towards the end of December a larval survey was commenced on the ravine which runs below the Peak Hotel and Peak Mansions, to Pokfulam Reservoir. This ravine has several tributaries in its upper part, which contains numerous potential breeding places for Anophelines and which flows through or near a populous area. A certain amount of nullah training has been done in a few tributaries, especially in the one which flows past Mount Austin Barracks. No complaints have been received regarding the contraction of malaria in this neighbourhood or in the Barracks. In the upper reaches of the ravine, including the main stream and its tributaries as far as and including the tributary from Mount Austin Barracks and its branches, only ten Anopheline larvae, one being A. maculatus the other nine A. aitkeni, were found in a careful survey.
Culicine larvae identified as C. vishnui, and Aedes japonicus were found. In some of the pools, there were small fish, and various natural enemies of mosquito larvae identified as water bugs, larvae of dragonfly and Mayfly larvae. This may account for the scarcity of Anopheline larvae. It is proposed to repeat the survey at intervals during the present year to obtain further information regarding this ravine.
Dengue.
Seventy-six cases were recorded from the Hospitals in 1931. Aegypti does not appear to be met with often on the Island, but Aedes albopictus is frequently found.
Filaria.
No cases of filarial infection were reported during the year, although C. fatigans and Aedes togoi, in which complete development of F. bancrofti has been observed, are common species.
Catching of mosquitoes in houses.
With a view to ascertaining what species of mosquitoes could be obtained, and the dissections of such Anophelines found, night catching was commenced at Taikoo on 18th May, 1931, and continued until 3rd July, 1931. An unoccupied bedroom was placed at the disposal of the Staff by arrangement with the General Manager, Taikoo Dockyard. From 9th September, 1931, until the end of the year, the catching was resumed in an empty garage on the outskirts of Wong Chok Hang Village, where a spleen rate of 82% has previously been obtained amongst the children. The investigator slept upon a camp bed protected by a mosquito curtain; outside this was a larger mosquito net supported on four poles. This net had flaps.
MM 106
Calculated on an average strength of 2336 the admission rate for the year was 20.55 per 1000. Amongst the Indian troops there were seventy five infections of which fifteen were in 1st quarter. eighteen in 2nd Quarter, twenty five in 3rd Quarter, and seven- teen in 4th Quarter. These work out for the year as 50.44 per thousand on an average strength of 1487.
Towards the end of December a larval survey was com- inenced on the ravine which runs below the Peak Hotel and Peak Mansions, to Pokfulam Reservoir. This ravine has several tributaries in its upper part, which contains numerous potential breeding places for Anophelines and which flows through or near a populous area. A certain amount of nullah training has been done in a few tributaries especially in the one which flows past Mount Austin Barracks. No complaints have been receiv- ed regarding the contraction of malaria in this neighbourhood or in the Barracks. In the upper reaches of the ravine including the main stream and its tributaries as far as and including the tributary from Mount Austin Barracks and its branches, only ten Anopheline larvae, one being A. maculatus the other nine A. aitkeni, were found in a careful survey.
Culicine larvae identified as C. vishnui, and Aedes japonicus were found. In some of the pools there were small fish, and various natural enemies of mosquito larvae identified as water bugs, larvas of dragon fly and May fly larvae. This may account for the scarcity of Anopheline larvae. It is proposed to repeat the survey at intervals during the present year to obtain further information regarding this ravine.
Dengue.
Seventy six cases were recorded from the Hospitals in 1931. Aegypti does not appear to be met with often on the Island, but Aedes albopictus is frequently..
Filaria.
No cases of filarial infection were reported during the year, although C. fatigans and Aedes togoi, in which complete develop- ment of F. bancrofti has been observed, are common species.
Catching of mosquitoes in houses.
With a view to ascertaining what species of mosquitoes could be obtained, and the dissections of such Anophelines found, night catching was commenced at Taikoo on 18th May, 1931 and continued until 3rd July, 1931. An unoccupied bed- room was placed at the disposal of the Staff by arrangement with the General Manager, Taikoo Dockyard. From 9th September, 1931 until the end of the year the catching was resumed in an empty garage on the outskirts of Wong Chok Hang Village where a spleen rate of 82% has previously been obtained aniongst the children. The investigator slept upon a camp bed protected by a mosquito curtain, outside this was a larger mosquito net supported on four poles. This net had flaps
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