Fig. 1

Positive predictive values (PPV) over time for varying Kato-Katz prevalence threshold values (0.5, 1, 2 and 5%) whilst sampling 200 individuals across the entire community (population size is set at 500). The trends are for the high adult burden setting where treatment has been carried out for 100% school-aged children and 100% adults annually for 10 years. The dashed black line is where the PPV is 0.9 and the grey line is where the time after stopping treatment is 2 years. The area shaded in red is where PPV < 0.9 and in green is where PPV ≥ 0.9. Corresponding PPV and negative predictive values (NPV) shown in Additional file 1: Table S1