1. Center for Child and Community Health Research, Department of Pediatrics, Johns Hopkins School of Medicine , Baltimore, Maryland , USA
2. Division of Infectious Diseases, Department of Medicine, Johns Hopkins School of Medicine , Baltimore, Maryland , USA
3. STI/HIV Program, Baltimore City Health Department , Baltimore, Maryland , USA
4. Department of Health, Behavior and Society, Johns Hopkins Bloomberg School of Public Health , Baltimore, Maryland , USA
5. Chase Brexton Health Services , Baltimore, Maryland , USA