was significantly lower in the respondents from the areas that received free bed nets from 2006 to 2007 than those that did not (Table 3). This result is consistent with other studies suggesting that the prevalence of malaria infection decreases in malaria endemic areas when bed net ownership or use increases [13,14,40]. It has been shown that ITNs can reduce the prevalence of parasitological malaria in areas with ITN coverage of >85%[13,14]. In the 2007 survey, ITN coverage was calculated as the ratio of respondents who reported to use an ITN the night before the survey compared to the total number of respondents who reported to sleep under an ITN the night before the survey. It was found that the ITN coverage was >90% in both study areas .
The geographical distribution of the haplotype variants of the key resistance genes, pfcrt, pfmdr1, dhfr, dhps was also consistent with the reported pattern of drug use in those areas [44-48]. This result may be explained by the over 30-fold increase in SP use and at least a 15-fold decrease in SP use along with a 7.5-fold decrease in CQ use between 2001 and 2007. Increasing use of SP in the transmission season by more than 400% and decreasing use of both SP and CQ during the transmission season by more than 95% suggests a direct effect by the availability of drugs.
Over the years, resistance to SP has been the major obstacle to its use at the time. In the Asembo area, resistance to SP remained a major problem through 1997 and 2001-2002 surveys, while in the Gem area, resistance was sporadically detected in 2001-2002 and 2003. Between 2003 and 2007, SP (29%) was still the most commonly used drug and chloroquine and amodiaquine were used with decreasing frequency as reported during the 1982-1987 surveys. In 2007, resistance to SP reduced significantly and decreased to 5% in the Asembo area compared to 69% in 2001-2002, while in the Gem area, resistance to SP increased from 24% in 2001-2002 to 62% in 2003-2007. d2c66b5586