Study visits will occur at Day 0, Week 2, and Months 1, 1.25, 1.5, 3, 3.5, 6, 6.25, 6.5, 9, and 12. Visits may include physical examinations and clinical assessments, blood and urine collection, optional stool collection, HIV testing, risk reduction counseling, and interviews/questionnaires. At Month 18, study staff will contact participants for follow-up health monitoring.