Time course of G. lamblia infection in mice. Trophozoite numbers in the mouse small intestine were determined at the indicated times. G. lamblia colonization peaked on PI days 4–7, and clearance was observed by days 14–21. Values represent mean ± SEM. The dashed line indicates the detection limit of trophozoite counts. Subsequent experiments were conducted on PI day 7 (colonization phase) and PI day 35 (post-clearance phase). n = 6–8/group. *P < 0.05 vs. day 0.