- Infectious Disease Subspecialty, Emory University.
- Internal Medicine Specialty, Emory University.
- Medicine, La Salle University, Mexico.
- Hubert Professor and Director of the Hubert Department of Global Health, Emory University.
- Professor of Medicine at Emory University School of Medicine.
- Principal Investigator and Co-Director of the Center for AIDS Research (CFAR), Emory University.
- Co-Principal Investigator of the Emory University HIV/AIDS Clinical Trials Unit and CDC.
- Early HIV diagnosis, access to care and antiretrovirals for hard-to-reach populations.
- Prevention of HIV infection and the translation of research results into public policy and practice.
- Addiction and drugs.
- Member of the Board of Directors of the International Antiviral Society of the United States (IAS-USA),
- President of the Scientific Advisory Committee of PEPFAR.
- NEJM Journal Watch Infectious Diseases Editor-in-Chief for HIV / AIDS and Associate Editor for Clinical Infectious
- Diseases as well as a member of the Editorial Board of the Journal of AIDS and Global Public Health.
- He was Executive Director of the National AIDS Council of Mexico (CONASIDA, the federal agency of the Mexican government responsible for AIDS policy at the national level), from January 1992 to August 1996.
- He was also a member of the UNAIDS Program Coordinating Board (1995-1997).