Sample size Sample size is calculated based on the differences of malaria prevalence before and after treatment in the arm 1 and arm2. The malaria prevalence used in the study is 15%, which is expected to decrease by 30% in arm 1 and persistent in arm 2. Sample size calculation is performed by WinPepi software with the assumed probability proportion of 10% and 15% in arm 1 and arm 2, respectively (5% significance level, 80% power, and 1:1 sample size ratio). Required sample size would be 686 subjects. We will recruit 1029 subject after considering design effect of 1.5.