This study will last 24 months and will involve several visits to the National Institutes of Health Clinical Center. Participants will be screened with a blood test for Loa loa parasites. Those who have a low number of Loa loa parasites in the blood will be asked to return for a full medical evaluation and the start of the treatment phase. Those who do not have Loa loa parasites in the blood, or those who have a high number of Loa loa parasites in the blood, are not eligible for this study treatment but may be eligible for other parasitic disease studies conducted by the National Institutes of Health.