Fig. 4

Comparison of WORMSIM predictions to longitudinal data on impact of mass drug treatment with albendazole. The data [24] consist of the number of women of childbearing age with no, light, medium, and heavy infection (cut-offs: 1, 2000, 4000 epg) based on a single Kato-Katz slide, determined at five time points: pre-control (October 2005), and 3, 12, 30, and 54 months after the first round of PC. Data were collected by means of cross-sectional surveys, i.e. not the same women were necessarily sampled at each time point. WORMSIM parameters for the overall transmission rate (ζ) and exposure heterogeneity (α _Exi ) were tuned to reproduce pre-control distribution of intensity of infection, assuming that the average saturation level for host egg output is 1500 or 2000 epg. Based on published data, we simulated 4-monthly treatment with albendazole targeting WCBA for 1 year, and 6-monthly from then onwards [24, 25]. Mass treatment coverage was assumed to be as reported during a single cross-sectional survey (85.8 %) and was assumed to remain stable for the entire 54-month study period. Because we had no exact information on the timing and coverage of PC targeting preSAC and SAC in the study area, we assumed that these were treated at the same time as the WCBA, and at equal coverage. Error bars represent 95 %-Bayesian credible intervals