149
18
servants were
136
in Old and New Shek O Villages. Two A, minimus were found in two houses of Old Shek O, but in New Shek O no mosquitoes were found in the village houses, which were searched as far
the temple on
the occasiON of the spleen survey. NJ inosquitoes were found in the cow sheds of the village but these were fairly well lighted and ventilated. The blood of fifty examined. One Club servant was actually suffering from malaria at the time and stated that he had been taking quinine, yet parasites were found without difficulty in the thick drop film, although none could be demonstrated in the thin film. During the course of erection of a residence a considerable number of workmen had been housed in the locality. As the majority do not use mosquito nets, they may be considered an important factor in the introduction and spread of malaria where suitable Anophelines are present.
Lai Chi Kok Gaol.
new
Owing to the incidence of malaria there during the latter half of the year, a visit was paid to the Gaols for both male and female prisoners and the surroundings inspected. Arrange- ments have been made for a complete survey, in the meantime, certain recommendations have been proposed for consideration.
Shing Mun Dam.
Visits have been paid in November and December to the proposed camp site for the labourers who will be engaged at work on the Dam, and to the site for European residences. Larval surveys have been done around them. From investiga- tions made, there has been a considerable amount of malaria in the Village of Woo Li Hop and amongst the contractor's coolies, engaged on making the road to the Dam, who were housed close to the village; steps have been taken with a view to making the Dam site healthy. Results of examinations for enlarged spleens and malarial parasites are given in Table XV and XIV.
Repetition of Pokfulam Ravine Survey.
During August a larval survey was repeated in the upper part of the stream which flows into Pokfulam Reservoir and which lies in the ravine below the Peak Hotel and Peak Mansions. The stream was searched as far as its junction with the branch from Mount Austin Barracks and all the included tributaries as well. As in December 1931, very few Anopheline larvae were met with, only 12 A. maculatus in the whole area. It is hoped to repeat the survey in 1933 after the rains, as numerous potential breeding places were present, and no malarial infections have been recorded from the locality.
197
Repetition of Surveys in Wong Chuk Hang Neighbourhood.
Larval surveys were done here from time to time. A large ravine swamp on the outskirts was searched in March and about 2,000 larvae of A. hyrcanus collected. In August practic- ally no Anophelines were found at the head of this swamp which was carefully searched as far as a bund which runs across it and which is 165 yards from the origin. In November this part had been recently trenched for cultivation, very few Anopheline larvae were found. Below the bund, however, the swamp yielded 760 larvae of A. jeyporiensis, 269 A. hyrcanus in three mornings' search by two searchers. Some of this portion had been in rice cultivation and there was water in the rice stubble, larvae of A. jeyporiensis were found in this as well as in the uncultivated swampy portion. In a rushy patch which had been dug up by cultivators numerous larvae of Mansonia and some Taeniorphynchus were found but none in the undisturbed portions, these larvae do not usually appear near the surface as they obtain their oxygen from the roots of plants. During the rainy season adult A. minimus could be obtained from huts in this locality whose ovaries were in an advanced state of development. So far larvae of A. minimus have not been found in numbers in hill streams during that season so attempts were made to ascertain if they could be met with in more quiet waters. Two ponds close to the swamp above mentioned containing vegetation and fed by seepages were searched in July and August, no Anopheline larvae were found. They had also been searched in February and November. In February a few A. minimus larvae were met with and plenty of A. hyrcanus, in November larvae of A. hyrcanus, A. jeyporiensis and a few A. minimus were found. It would seem that larvae of A. hyrcanus and A. jeyporiensis are more plentiful at certain seasons. In December portions of the main stream which flows through the area were seached. In one portion about 700 yards long, lying amongst the hills and receiving tributaries from them, 683 A. minimus larvae, 662 A. hyrcanus, 284 A. maculatus, 10 A. jevporiensis were obtained. A portion 300 vards long after the stream had left the hills and was receiving no tributaries yielded 190 A. hyrcanus larvae and 6 A. minimus.
Repetition of Surveys around New G.0.H. site.
A complete survey had been done during the period of July 7th August 7th. 1931 over an area of half mile radius, as indicated by the circle on attached map, the centre of the circle corresponding to the site. The only Anopheline larvae found, were those of A. maculatus and these in great abundance. A spleen rate done by the Acting Malariologist resulted in the examination of 150 children and the finding of 22 enlarged spleens, a rate of 14%. Thick and thin blood films were taken from 21 servants living in houses along the Pokfulam Road situated near the site, but no malarial infection was found.
150