Higher HIV prevalence is commonly observed among migrant populations in Sub-Saharan Africa. However the extent to which migration is a cause or consequence of HIV infection is largely unknown. Here, we use population-based, longitudinal data to assess the association between duration of residence since migration into a community and HIV incidence in Rakai District, Uganda.
We used prospective data from HIV-negative participants residing in thirty communities under continuous surveillance between 1999 and 2015 in the Rakai Community Cohort Study (RCCS), an open population-based census and cohort of adults aged 15-49 in rural south-central Uganda. Migrants were identified during census and classified as individuals who moved to a new community with intention to stay. Newly HIV-positive individuals were considered incident HIV cases if they had an HIV-negative test result at a prior survey. Poisson regression with generalized estimating equations was used to estimate incidence rate ratios (IRR) of HIV infection associated with years since arrival for migrants relative to long term-residents with adjustment for demographics, sexual risk behaviors, and calendar time.
HIV incidence was assessed among 13,991 HIV-negative individuals of whom 57% (n=8,049) were women and 34% (n=4571) were classified as migrants. Participants were followed for 85,654 person-years (pys) during which 802 incident HIV events were detected (n=313 in men; n=489 in women). Overall, incidence was 1.6/100pys in recent migrants (arrived <2 years), 0.97/100pys in non-recent migrants (>2 years), and 0.88/100pys among long-term residents. Among women, HIV incidence was significantly elevated in recent migrants relative to long-term residents before and after adjustment for potential confounders (IRR=1.86, 95%CI:1.43-2.41; adjIRR=1.60, 95%CI: 1.21-2.13) but not in non-recent migrants (IRR=0.89, 95%CI:0.71-1.12; adjIRR=0.97, 95%CI: 0.76-1.23). We observed no significant increases in HIV risk among recent (IRR=1.34, 95%CI:0.78-2.32; adjIRR=1.36, 95%CI:0.78-2.37) or non-recent migrant men (IRR=1.03, 95%CI:0.71-1.48; adjIRR=1.12, 95%C1: 0.77-1.64).
These data suggest that the earliest years after migration are associated with increased risk of HIV acquisition in women but not men in rural East Africa. These findings highlight the need for timely interventions targeted to migrant populations, particularly women, to reduce HIV incidence in Sub-Saharan Africa.