Conceptual framework and research methods for migration and HIV transmission dynamics

Abstract

Migration and mobility have had a profound influence on the global HIV epidemic. We propose a network-dyadic conceptual model to interpret previous literature and inform the development of future research with respect to study design, measurement methods, and analytic approach. In this model, HIV transmission is driven by risk behaviors of migrants that emerges and is enabled by mobility, the bridging of sub-epidemics across space and time, and the displacement effects on the primary residential sending community for migrants. To investigate these causal pathways, empirical study designs must measure the relative timing of migratory events, sexual risk behaviors, and incident HIV infections. Network-based mathematical models using empirical data on partnerships help gain insight into the dynamic disease transmission systems. Although the network-dyadic conceptual model and related network methods may not address all questions related to migration and HIV, they provide a unified approach for future research on this important topic.

Figure 1. Network-Dyadic Conceptual Model for Migration and HIV

Demographic processes are shown in orange slanted boxes, and the main infection transmission process in blue. The four nested levels within the model (population, network, dyad, and index) are shown with dotted lines to show their porous borders. A partnership dyad is formed by the union of two index individuals; with concurrency, dyad formation can occur multiply before any dyad dissolution occurs. HIV infection may only occur within a dyad between the formation and dissolution processes.

Figure 2. Directed Acyclic Graph (DAG) for HIV Infection within Stable Couples with Concurrency

This DAG represent two possibilities for causal pathways from partner travel to index infection within a long-term stable couple in which both members are uninfected at baseline.