I have focused my career in medicine and infectious diseases on creating new knowledge to improve the health of marginalized and underserved populations in the US and globally. I have been involved in HIV/AIDS care, teaching and research since 1981. I served as Director of the Yale AIDS Program from 1991 to 2009. More recently, although still working domestically on HIV/AIDS, a major focus my work has been to integrate HIV and TB care and treatment in co infected patients in South Africa with the aim of improving diagnosis, treatment and outcomes of both diseases. This has led to the recognition of the epidemic of extensively drug resistant tuberculosis (XDR TB) in Tugela Ferry in rural KwaZuluNatal South Africa and now focuses on the diagnosis, treatment and reduction of transmission of XDR TB and multiple drug resistant (MDR) TB and in HIV co-infected patients. During my career, I have developed multidisciplinary teams and constructed observational studies, clinical trials and operational research in community and health care settings to address complex infectious diseases challenges. I have also served as a mentor for students, residents, fellows and faculty and other health care workers in the US and multiple international sites, with a current and continuing focus in rural South Africa.