M 122
(c) THE CATCHING AND DISSECTING OF ANOPHELINES FOR MALARIAL INFECTION.
(1) Wong Chok Hang Village and Surroundings (Little Hong Kong).
50. Catching operations were continued throughout the year. The locality is surrounded by hills on all sides except in the direction of the sea. A stream with several branches flows through it. A ravine which was formerly a rice swamp drains into the main stream. At the end of 1933 most of this swamp was ditched and divided into rectangular plots for growing crops such as Indian corn, three or four small plots, however, were left for rice growing and rice was also planted in such of the ditches as held water. The people of the village live in houses built of stone and roofed with tiles; the others in huts made of bamboo and thatch. All of them are engaged in growing crops and rearing pigs. The pigsties have low walls and high roofs, and so are unsuitable as daytime resting places for mosquitoes.
51. In 1931 a high spleen rate was found amongst the children and in 1932 a microfilaria rate of 12% was obtained from the examination of 106 persons, the blood being taken at night.
52. The arrangements for catching were as follows: a coolie collected for one hour, from dusk onwards, in the tent provided, and made another collection at dawn. He was supplied with camp bed, mosquito net, alarm clock and electric torch. This arrangement, judging from results obtained in 1933, appeared to offer the best prospects for securing A. maculatus. Unfortunately in August the tent was found unfit for further service and so night catching was discontinued.
53. Culicines not readily obtainable were captured in the night catches: - Aedes niveus, M. (M) uniformis, M. (C) crassipes. The blood of the coolie was examined monthly for microfilaria and for malaria parasites, but none were found; however, two of the members of his family who resided in the neighbourhood suffered from malaria.
54. From 8.30 a.m. till 11.30 a.m., daily catching was done by the coolie in two groups of huts on alternate days. The groups were situated north and south of Island Road, the northern group along the stream banks, close to places where A. minimus larvae were in abundance, the southern group about 440 yards downstream where the larvae of A. minimus were scarce.
55. 2443 A. minimus were collected in 168 morning catches in the northern group or 14.54 per morning, 359 were collected in 136 mornings from the southern group or 2.64 per morning, about 1/5 of the catch obtained from the northern group. It would thus appear that habitations closest to the breeding places receive most attention from this Anopheline. Table X gives the
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M 122
(c) THE CATCHING AND DISSECTING OF ANOPHELINES FOR MALARIAL INFECTION.
(1) Wong Chok Hang Village and Surroundings (Little Hong Kong).
50. Catching operations were continued throughout the year. The locality is surrounded by hills on all sides except in the direction of the sea. A stream with several branches flows through it. A ravine which was formerly a rice swamp drains into the main stream. At the end of 1933 most of this swamp was ditched and divided into rectangular plots for growing crops such as Indian corn, three or four small plots, however, were left for rice growing and rice was also planted in such of the ditches as held water. The people of the village live in houses built of stone and roofed with tiles; the others in huts made of bamboo and thatch. All of them are engaged in growing crops and rearing pigs. The pigsties have low walls and high roofs, and so are unsuitable as daytime resting places for mosquitoes.
51. In 1931 a high spleen rate was found amongst the children and in 1932 a microfilaria rate of 12% was obtained from the examination of 106 persons, the blood being taken at night.
52. The arrangements for catching were as follows: a coolie collected for one hour, from dusk onwards, in the tent provided, and made another collection at dawn. He was supplied with camp bed, mosquito net, alarm clock and electric torch. This arrangement, judging from results obtained in 1933, appeared to offer the best prospects for securing A. maculatus. Unfor- tunately in August the tent was found unfit for further service and so night catching was discontinued.
53. Culicines not readily obtainable were captured in the night catches :-Aedes niveus, M. (M) uniformis, M. (C) crassipes. The blood of the coolie was examined monthly for microfilaria and for malaria parasites, but none were found, however two of the members of his family who resided in the neighbourhood suffered from malaria.
54. From 8.30 a.m. till 11.30 a.m., daily catching was done by the coolie in two groups of huts on alternate days. The groups were situated north and south of Island Road, the north- ern group along the stream banks, close to places where A. minimus larvae were in abundance, the southern group about 440 yards down stream where the larvae of A. minimus were scarce.
55. 2443 A. minimus were collected in 168 morning catches in the northern group or 14.54 per morning, 359 were collected in 136 mornings from the southern group or 2.64 per morning, about 1/5 of the catch obtained from the northern group. It would thus appear that habitations closest to the breeding places receive most attention from this Anopheline. Table X gives the
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