X1000307-1951-52_Part01 — Page 50

MALARIA AND MOSQUITO CONTROL

Control of Breeding.

150. The larval control programme covers the whole of the inhabited area of Hong Kong island, and in Kowloon, an area from Lai Chi Kok in the west to a mile beyond the Airport in the east, and extending as far north as the Kowloon Reservoir. In addition, the area from Lyemun to Rennie's Mill, and Cheung Chau Island are also included.

151. With the setting up of a squatter resettlement camp at Ngau Tau Kok, the larval control programme has been extended beyond that area since the beginning of 1952.

The

camp includes a large population with infected people, and in the interest of the nearby Kai Tak Airport, this extension of work was essential.

162. Another new commitment at the beginning of 1952 is the malaria control work at the Tai Lam Chung Reservoir site. While preliminary construction work is in progress, the place is to be made safe from malaria for the occupation of a large labour force. Vigorous initial work in the form of canalizing and training of streams, has now been done.

153. Since May, the use of malario] as a larvicide has bech entirely discontinued; its replacement by

replacement by water-miscible gammexane brought numerous advantages, the chief being the saving of transport, labour, expense, and its harmlessness to vegetation with the dosage that was employed. The use of gammexane bricks (25% gammexane and 75% plaster of Paris) which was introduced last year on suitable potential breeding places like tanks and small pools, continued to prove very effective in controlling breeding,

154. Where possible, permanent work in the form of cement filling of rock holes was continued along the sea-coast at Shek-0, Stanley and Green Island. This work brought excellent results as it has permanently cleared the breeding places of Aedes togoi.

156. The fact that gammexane miscible powder leaves no readily discernible trace after having been applied, calls for even closer and stricter supervision of labour. Numerous check- ing catches and surveys were done in the controlled area of Kowloon and Hong Kong Island, but no anophelines, either larval or adult, could be found. Constant vigilance, however, is being maintained, as there is no satisfactory natural barrier between the controlled and uncontrolled areas, and the condition is made worse by heavy land and sea transport between these places.

Imagocides.

156. Quarterly residual D.D.T. spraying was undertaken during the warmer months at Sai Wan, Lyemun, Shek-0, Tele- graph Bay and Pokfulam, as a supplementary barrier check in villages on the perimeter of the larval controlled area, and in all Government buildings in the New Territories.

Mosquito nuisances.

157. Mosquito nuisances were investigated on behalf of the Urban Council at various districts. As a result, 93 legal notices were applied for, and 15 prosecutions conducted during the year.

158. In Cheung Chau Island, good results were achieved in regard to mosquito infestation since the extended programme was undertaken.

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