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seven gaol admissions contained microfilaria.
These were taken in the day-time. Material consisting of thick blood films con- taining microfilaria, and preparations of filaria from the mos- quitoes, have been forwarded to Dr. R. Hoeppli, Peiping Union Medical College, for investigation and report.
(c) CATCHING AND DISSECTING OF ANOPHELINES FOR MALARIAL INFECTION.
(1) Wong Chuk Hang Village & Surroundings. Night catching by trapping was done during January in an empty garage on the outskirts of the village where a spleen rate of 82 per cent had been obtained in 1931 by the Acting Malario- logist amongst 62 children examined in the locality. The in- vestigator slept upon a camp bed protected by a mosquito net, outside this was a larger mosquito net supported on four poles. This larger net had flaps in the sides weighted by rollers. When in use the flaps were rolled up. At intervals, the investigator got up, let down the flaps and searched for mosquitoes with an elec- tric torch. On 22nd January a visit was paid to the locality and five A. minimus gorged with blood were found in huts. These huts are thatched with palm leaf which also enters largely into the composition of the walls. Night catching was discontinued at the garage but was resumed again in May in a room of a house owned by Mr. Li who kindly placed it at the disposal of the Bureau, and the trapping apparatus was transferred there from the garage.
In July an I.P. tent was pitched near the house and a coolie engaged to look after it, sleep in it and catch mos- quitoes. Streams which had been found to harbour Anopheline larvae especially those of A. maculatus and A. minimus were close to and on all sides of the house and tent. Night catching was done on Monday, Tuesday, and Wednesday of each week by the probationers in turn,
The tent was inspected on arrival at 8 p.m. to ascertain if the coolie were at his post and occasionally during the night. Catching was done at intervals until midnight in house and tent and the coolie then brought up his catching bottle and its con- tents to the house. Between midnight and dawn another catch was made and again before daylight. The coolie was provided with camp bed, mosquito net, alarm clock and electric torch: when not actually catching he remained inside the net. His blood has been examined on five occasions at monthly intervals: neither microfilaria nor malaria parasites were found, although these were present in local people. Mosquitoes with one or other of such infections have been captured by him in the tent from time to time, so that it would appear that A. minimus does not confine its visits to one habitation. The probationer on duty brought the results of the night catches to the Laboratory on Tuesday, Wednesday and Thursdays mornings on other days of the week except Sundays and holidays, morning catches were
as well.
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done by him between 9.30 and 12.30 a.m. and the results of the tent catches of the previous night obtained. Additional morning catches were done from time to time by the other probationers On reaching the Laboratory the mosquitoes were trans- ferred to small lamp glasses both ends of which were covered with netting. These were placed in a box the bottom of which was lined with lint always kept moist. Raisins were placed on top of the lamp glasses for the mosquitoes to feed upon, box is provided with legs which stand in saucers containing a disinfectant to prevent ants gaining access. The dissection were done by the aid of the binocular microscope in the usual manner. All positive results of dissections were submitted to the Malario- logist before being recorded.
The
Results of catches and dissections are shown in Tables VII, VIII, IX, X, XI. In this neighbourhood the best places for obtaining Anophelines in the morning catches, were in the palm leaf huts around the village; they were not so readily found in the village houses built of stone and roofed with by tiles. During one morning, two probationers spent the same time, one in searching huts, the other in searching village houses. Nineteen Anophelines were obtained from the huts, six from the houses. The Anophelines were most commonly met with on the dingy niosquito curtains, and some on the sides of the huts and beneath tables in dark corners. An uninhabited hut used as a tool shed was repeatedly searched but only on one occasion was an Ano- pheline found in it-an A. minimus, although they were fre- quently round in adjacent huts. No Anophelines were found in empty houses or in the tent if unoccupied the previous night. This would indicate that a blood meal and not shelter was the object of their frequenting habitations. Numerous pig sties were searched but harboured no Anophelines; these, however, have low walls and high roofs supported on pillars and would not be likely resting places. There were no cowsheds. A. minimus was the commonest Anopheline found in day and night catches, it was caught at all hours from dusk until dawn; in the last quarter of the year A. jeyporiensis was encountered in compara- tively large numbers. In most larval surveys the larvae of A. maculatus are in great majority especially when compar- ed with A. minimus, but in these catches the adults were scarce and that in an area where their larvae were numerous at all times. Few A. hyrcanus were captured but their larvae are not found abundantly in hill streams. It is proposed to move the tent closer to a swamp where their larvae have been obtained in large numbers and which is near habitations from which infected Anophelines have been obtained. The first infection recorded was in April, one oocyst 15 x diameter in an A. minimus, and the first sporozoites were met with also in an A. minimus in the middle of June, The inhabitants of the locality rendered every assistance and informed the investigators that malaria did not start until July, a statement which was confirmed in this instance by the results of the dissections of
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