Angela Ulrich

Interdisciplinary Training

Angela Ulrich

"Concurrency and acute infection: drivers of the HIV epidemic amoung men who have sex with men in Lima, Peru?"

My interdisciplinary training and doctoral dissertation work combine epidemiology and
mathematical modeling to investigate how concurrent sexual partnerships and acute HIV
infection potentiate epidemic spread of HIV among men who have sex with men (MSM). My
mentors are Drs. Ann Duerr (Epidemiology) and Steven Goodreau (Anthropology). Traditional
epidemiological studies, which focus on the risk of acquiring disease, are inadequate to study
the population-level impacts of concurrency and therefore other approaches, such as network
models of disease transmission, are essential to accurately capture the complexities of sexual
networks. Through my work on the training grant, I will conduct and analyze two traditional
epidemiological studies in Lima, Peru: a descriptive cross-sectional analysis of features of MSM
sexual networks and a case-control study of risk factors for HIV acquisition. These studies will
include an analysis of the level of concurrent partnerships among MSM, how concurrency with
a female partner may act as a ?bridge? for HIV transmission from MSM to the heterosexual
population, and a detailed analysis of risk factors associated with HIV acquisition. I will then
build and utilize a mathematical model that incorporates network dynamics and empirical
parameter estimates to assess the combined effect of high infectivity during acute infection and
the observed level of concurrency on onward HIV transmission among MSM.  Finally, I will
conduct a comparison of two methods (phylogenetic analysis of HIV from HIV-infected MSM in
Lima and network models derived from this same population) to assess the impact of acute
infection on onward transmission among MSM.