The status of malaria before and after distribution of ITNs from 1999 to 2006 in two districts of Khammouanne Province, Lao P.D.R

Abstract

In 1999, an insecticide-treated net (ITN) distribution project was started in several malaria-endemic villages in Lao P.D.R., namely Vientiane, Bolikhamxay and Khammouanne Provinces. After the completion of the project, it was found that the ITNs were effective for malaria control based on the analysis of the slide positivity rate for malaria parasites between 1999 and 2000 [6]. We conducted malariometric, entomological and KAP surveys in 2005-06 to confirm the status of malaria and to determine the effectiveness of ITNs in three different socioepidemiological areas (near city, rural and remote), represented by the Xebangfay and Boualapha districts, Khammouanne Province. A marked decrease in the annual malaria incidence and slide positivity rate was noted from 1999 to 2006 in the two districts. The malaria prevalence was significantly reduced in near city areas (5.6%-10.7% in 1999 to 0% in 2005-06) and rural areas (21.4%-50.9% in 1999 to 0%-1% in 2005-06). Twelve positive cases were recorded in remote areas (3.4 - 7.7% in 2006). The illiteracy rate was significantly higher among the respondents in the remote (83.9%) than among those in the near city (32.7%) and rural (54%) areas. In all areas, more than 50% of the villagers indicated that they were not aware of malaria. Similarly, about 60% of the respondents were found to have incorrect knowledge concerning malaria transmission. In remote, 40.9% of the respondents were aware of the methods to prevent malaria infection and 49.5% used mosquito nets throughout the year, rates significantly lower than the corresponding rates in near city and rural. The density of persons per net in remote (3.1-5.9) was considerably higher than that in near city (1.8-2.1) and rural (1.2-2.7). Malaria vector mosquitoes, such as An. minimus and An. nivipes were collected by human-baited adult collection, and cow-baited and CDC light traps. The results of the analysis suggested that the lower the number of persons per net the more effective the reduction of malaria morbidity in these areas. It is imperative that ITN distribution and health education regarding malaria be strengthened, especially in remote, but also in other areas. © 2007, Japanese Society of Tropical Medicine. All rights reserved.