This is a phase IIa, randomized, placebo-controlled, single-blinded superiority treatment study to compare placebo to once daily doses of 6mg auranofin for adults with amebiasis or giardiasis. A sample size of 68 subjects enrolled with amebiasis (34 per arm) and 68 with giardiasis (34 per arm); Power based on 60 subjects with amebiasis and 60 with giardiasis completing the study. Primary objectives are 1) to compare the proportion of subjects with stools positive by rapid EIA and positive antigen detection EIA for E. histolytica at enrollment with resolution of diarrhea (less than 3 loose stools/24 hrs) by Day 7 for E. histolytica infections and 2) to compare the proportion of subjects with stools positive by rapid EIA and positive antigen detection EIA for Giardia at enrollment with resolution of diarrhea (less than 3 loose stools/24 hrs) by Day 5 for Giardia infections. The length of this study is set for 3.5 years; subject participation is 7 days treatment (amebiasis) and 5 days (giardiasis) with follow-up until day 28