Influence of stagnation of water pathways on mosquito population density in connection with malaria transmission in the Solomon Islands.

Malaria is the major health problem in the Solomon Islands. The area of Guadalcanal plains has been known as the most malarious area of the Solomons. In spite of well executed DDT indoor spraying, malaria transmission was not interrupted. The causative factors responsible for this persisting transmission appeared to rest on three factors: refractoriness of Anopheles farauti to DDT spraying; the habit of people to stay outside late in the evening and a marked outdoor biting tendency of A. farauti. It was found that DDT indoor spraying alone had little impact on interruption of malaria transmission. This study conducted in early 1974 was planned to observe the change of mosquito population density in relation to the constriction of the river-mouth in north Guadalcanal in order to consider alternative means for malaria control. With the result of this study, one can assume, with a reasonable degree of certainty, that the improvement of the malaria situation in north Guadalcanal would be associated with steady flow of the river water by maintaining the river/stream-mouth in an open condition.