I am a senior professor in Epidemiology at the Federal University of Ceara. I have been working with HIV/AIDS since 1986 addressing hard-to-reach population and using Respondent Driven Sampling since 2005. I was the PI of the first (2009) and second (2016) RDS-survey among MSM in Brazil conducted in 10 and 12 cities, respectively. I have published about 190 papers in peer-reviewed journals and 15 books and/or chapters. I am the vice-president of ABRASCO.