TAPS Postdoctoral Fellows

Natasha Ludwig-Barron PhD MPH


Natasha Ludwig-Barron, PhD, MPH, comes to the TAPS Fellowship with more than 10-years of public health research and practice experience. Her mentorship team includes Drs. John Sauceda (UCSF), Julia Lechuga (UTEP) and Elise Riley (UCSF), who offer expertise in HIV, substance use, Latinx health, and epidemiologic research methods along the US-Mexico Border. Dr. Ludwig-Barron is a mixed methods researcher whose research interests incorporate an ecological approach to understanding the syndemic of HIV/AIDS, substance use, and gender inequities, with the goal of improving the health and wellbeing of marginalized communities. After earning her MPH at Emory University, Dr. Ludwig-Barron completed a Hispanic-Serving Health Professions Schools (HSHPS) Fellowship where she conducted HIV and substance use research along the U.S.-Mexico Border in San Diego, CA, and later served as an Epidemiologist with the Los Angeles County Department of Public Health.

She completed her doctorate in Epidemiology at the University of Washington, which was supported by a NIH Diversity Supplement. Her dissertation research focused on HIV-HCV risk environments and predictors of suboptimal HIV care among persons who inject drugs living with HIV (PWID-LH) in Kenya. As a TAPS Fellow, she has two pilot awards through the UCSF Resource Allocation Program (RAP) and Fordham University’s Research and Ethics Training Institute (RETI), where she will a) geospatially characterize sub-group of Latinx PWID using a HIV risk environment framework in Ciudad Juárez, Mexico, and b) highlight ethical research considerations when incorporating biometric enrollment technology into PWID communities.​​​​​​

Natasha Ludwig-Barron PhD MPH


Ahmad Danesh, MD, MPH, Ph.D., received his Ph.D. in Epidemiology from the School of Public Health at Tehran University of Medical Sciences (TUMS) after completing his master’s degree in public health at the University of Connecticut (UConn). As an assistant professor, he has teaching experience in epidemiology and research methodology at Golestan University of Medical Sciences (GoUMS). He also has ten years of experience treating substance abuse disorders as a medical practitioner in Iran.

His research interest is alcohol dependency and its effect on HIV risky behaviors among HIV-vulnerable groups (e.g., PWID, MSM, FSW). In recent studies, he explored the prevalence of polysubstance abuse, specifically methamphetamine and alcohol consumption, among clients of Methadone Maintenance Treatment (MMT) centers. The findings have shown how much alcohol consumption could be prevalent among HIV-vulnerable groups, even in countries with alcohol consumption laws. He is now interested in exploring the effect of alcohol dependency on HIV transmission among HIV-vulnerable groups. As a TAPS fellow, he plans to identify the pervasiveness of alcohol consumption (binge drinking and harmful alcohol consumption) among PWID and MSM groups and its association with HIV-risky behaviors. He also plans to identify factors that could reduce or enhance the association between alcohol consumption and HIV-risky behaviors at the individual and community levels. The findings could be further analyzed for novel approaches to better address alcohol consumption among HIV-vulnerable groups, which may be needed for better controlling the HIV epidemic in the future.

Holly Nishimura PhD MPH


Holly Nishimura, PhD, MPH, received her PhD from the Department of International Health from the Johns Hopkins Bloomberg School of Public Health. Dr. Nishimura’s research interests include understanding the social and structural factors that contribute to inequalities in health outcomes globally, with a particular focus on gender and economic inequalities. She is also actively engaged in efforts to decolonize global health and improve equity and inclusion in academia. Her dissertation research used a mixed methods approach to understand the relationship between transactional sex and HIV among men in Rakai, Uganda. Dr. Nishimura received the Fulbright-Fogarty and Ruth L. Kirschstein National Research Service Award (NRSA) from NIMH for her predoctoral training. Prior to entering the PhD program, she received an M.P.H. in Maternal, Child, and Adolescent Health and B.A. in Integrative Biology from UC Berkeley. As a TAPS fellow, she will be working with Dr. Carol Camlin on the Owete study, which uses a social network approach to promote HIV self-testing and linkage to care among fishermen at Lake Victoria.

Kristopher Jackson, PhD


Kristopher Jackson, PhD, is a nurse practitioner and nurse scholar who, over the last decade, has worked in a variety of inpatient and outpatient settings at the Hospital of the University of Pennsylvania, UCSF Medical Center, and California Pacific Medical Center. In December 2021, Kristopher completed his PhD in Nursing from the University of New Mexico after defending – with distinction – his doctoral dissertation entitled, “Advertised Health and Risk-Taking Behaviors of Internet-Based MSM Sex Workers in the United States.” As a PhD student, he coauthored several peer-reviewed studies exploring advertised risk taking among Internet-based MSM sex workers and topics related to sexual and gender minority healthcare. As a new TAPS fellow, Kristopher is currently enrolled in the 11-month Epidemiology MPH program at UC Berkeley. Kristopher has a particular interest in the use of novel data collection methods to gain insight into hidden and/or stigmatized populations of people at risk for HIV, as well as how to approach HIV and harm reduction practices in populations of individuals with multiple stigmatized, oftentimes intersecting social identities.


Neia prata Menezes PhD MPH


Neia Prata Menezes, PhD, MPH, received her Master’s degree in Global Epidemiology from the Rollins School of Public Health at Emory University. She subsequently completed her PhD in Infectious Disease Epidemiology at the Johns Hopkins Bloomberg School of Public Health. Dr. Prata’s research explores behavioral, social, and structural barriers and facilitators to HIV prevention and treatment services among historically marginalized populations. For her doctoral dissertation, she evaluated whether injection drug networks inform HIV prevention behaviors of people who inject drugs (PWID) in India. Specifically, she assessed the roles of injection drug network size, position, and peer behaviors on PWID engagement in HIV testing, medication for opioid disorder, or syringe services. Prior to her dissertation, she worked as a research analyst within Global Health Sciences at UCSF to implement a variety of monitoring and evaluation and surveillance projects to characterize programmatic gaps among vulnerable populations across sub-Saharan and PEPFAR-funded countries. As a TAPS fellow, Dr. Prata hopes to build on her expertise and explore the design, implementation, and evaluation of social and behavioral interventions to improve access and utilization of HIV services among vulnerable groups. She is also interested in deepening her understanding of the intersection of stigma, substance use, and social support on the health outcomes of vulnerable populations.