Interruption of malaria transmission by chloroquinized salt in Guyana, with observations on a chloroquine-resistant strain of Plasmodium falciparum

ABSTRACT

Malaria and its local vector, Anopheles darlingi, were eradicated from the coastlands and near interior of Guyana by DDT house-spraying in 1945-51. In the remote interior, where 10 percent of the population live, only partial control could be achieved, owing to the semi-silvatic habits of A. darlingi and the considerable movement of the sparce population; low malaria endemicity persisted in these areas with occasional localized outbreaks. In the south-west the problem was further complicated by the presence of malaria across the frontier. During the years 1961-65, the use of chloroquinized salt was made compulsory over an area of some 109,000 km(sq), covering a population of 48,500. Satisfactory results were obtained over 84 percent of this area within 6 months of the start of the campaign; only four cases of malaria were seen in four years. In the south-west, however, an initally favourable trend was reversed in 1962 with the introduction of a chloroquine-resistant strain of Plasmodium falciparum from Brazil. The situation was brought under control by house-spraying with DDT and interruption of transmission is expected. (AU)