HIV incidence among non-migrating persons following a household migration event: a population-based, longitudinal study in Uganda

Background

The impact of migration on HIV risk among non-migrating household members is poorly understood. We measured HIV incidence among non-migrants living in households with and without migrants in Uganda.

Methods

We used four survey rounds of data collected from July 2011-May 2018 from non-migrant participants aged 15-49 years in the Rakai Community Cohort Study, an open, population-based cohort. Non-migrants were individuals with no evidence of migration between surveys or at the prior survey. The primary exposure, household migration, was assessed using census data and defined as ≥1 household member migrating in or out of the house from another community between surveys (∼18 months). Incident HIV cases tested positive following a negative result at the preceding visit. Incidence rate ratios (IRR) with 95% confidence intervals were estimated using Poisson regression with generalized estimating equations and robust standard errors. Analyses were stratified by gender, migration into or out of the household, and the relationship between non-migrants and migrants (i.e., any household migration, spouse, child).

Findings

Overall, 11,318 non-migrants (5,674 women) were followed for 37,320 person-years. 28% (6,059/21,370) of non-migrant person-visits had recent migration into or out of the household, and 240 HIV incident cases were identified in non-migrating household members. Overall, non-migrants in migrant households were not at greater risk of acquiring HIV. However, HIV incidence among men was significantly higher when the spouse had recently migrated in (adjIRR:2·12;95%CI:1·05-4·27) or out (adjIRR:4·01;95%CI:2·16-7·44) compared to men with no spousal migration. Women with in- and out-migrant spouses also had higher HIV incidence, but results were not statistically significant.

Interpretation

HIV incidence is higher among non-migrating persons with migrant spouses, especially men. Targeted HIV testing and prevention interventions such as pre-exposure prophylaxis could be considered for those with migrant spouses.

Funding

National Institutes of Health, US Centers for Disease Control and Prevention.

Research in context

We searched PubMed for studies focused on HIV acquisition, prevalence or sexual behaviors among non-migrants who lived with migrants in sub-Saharan Africa (SSA) using search terms such as "HIV", "Emigration and Immigration", "family", "spouses", "household", "parents", and "children". Despite high levels of migration and an established association with HIV risk in SSA, there is limited data on the broader societal impacts of migration on HIV acquisition risk among non-migrant populations directly impacted by it.There has been only one published study that has previously evaluated impact of migration on HIV incidence among non-migrating persons in sub-Saharan Africa. This study, which exclusively assessed spousal migration, was conducted in Tanzania more than two decades earlier prior to HIV treatment availability and found that non-migrant men with long-term mobile partners were more than four times as likely to acquire HIV compared to men who had partners that were residents. To the best of our knowledge, this is the first study to examine the effect of non-spousal migration, including any household migration and child migration, on HIV incidence among non-migrants.

Added value of this study

In this study, we used data from the Rakai Community Cohort Study (RCCS), a population-based HIV surveillance cohort to measure the impact of migration on HIV incidence for non-migrant household members. The RCCS captures HIV incident events through regular, repeat HIV testing of participants and migration events through household censuses. Our study adds to the current literature by examining the general effect of migration in the household on HIV incidence in addition to child, and spousal migration. Using data from over 11,000 non-migrant individuals, we found that spousal, but not other types of household migration, substantially increased HIV risk among non-migrants, especially among men. Taken together, our results suggest that spousal migration may be associated with an increased risk of HIV acquisition in the period surrounding and immediately after spousal migration.

Implications of all the available evidence

Our findings suggest that spousal migration in or out of the household is associated with greater HIV incidence. Targeted HIV testing and prevention interventions such as pre-exposure prophylaxis could be considered for men with migrant spouses.

Perceived stigma among people with TB and household contacts

BACKGROUND: TB-related stigma hampers access to diagnosis and treatment, making it important to understand the demographic and clinical characteristics associated with perceived TB stigma. TB stigma has not been studied in household contacts before, yet they comprise an important population for epidemic control, with high risk of infection.METHOD: A cross-sectional study was conducted among people with TB and household contacts in South Africa using a 12-item perceived TB stigma scale (score range: 0-36). Demographic and clinical characteristic data were collected using a close-ended questionnaire. A linear mixed-effects regression model was used to explore perceived TB stigma levels and its associated characteristics.RESULTS: The sample included 143 people with TB and 135 household contacts. The mean perceived TB stigma score among people with TB was 22.1 (95% CI 21.1-23.1) and 22.2 (95% CI 21.1-23.3) among household contacts. Being in the same household explained 24.3% variability in stigma perception. Residence in the urban study site (Soshanguve) and a positive HIV diagnosis were associated with higher perceived TB stigma score.CONCLUSIONS: People with TB and household contacts have similarly high prevalence of perceived TB stigma. Positive HIV status and urban location were associated with higher prevalence of perceived TB stigma.

Time to care-seeking for TB symptoms

BACKGROUND: Early presentation to healthcare facilities is critical for early diagnosis and treatment of TB. We studied self-reported time to care-seeking from the onset of TB symptoms among primary healthcare clinic (PHC) attendees in Limpopo Province, South Africa.METHODS: We used data from participants enrolled in a cluster-randomized trial of TB case finding in 56 PHC clinics across two health districts. We fitted log-normal accelerated failure time regression models and we present time ratios (TRs) for potential risk factors.RESULTS: We included 2,160 participants. Among the 1,757 (81%) diagnosed with active TB, the median time to care-seeking was 30 days (IQR 14-60); adults sought care later than children/adolescents (adjusted TR aTR 1.47, 95% CI 1.10-1.96). Among those not diagnosed with TB, the median was 14 days (IQR 7-60); being HIV-positive (aTR 1.57, 95% CI 1.03-2.40); having less than grade 8 education and currently smoking were associated with longer time to care-seeking. In the combined analysis, living with HIV and having underlying active TB was associated with faster care-seeking (TB status x HIV interaction: TR 0.68, 95% CI 0.48-0.96).CONCLUSION: Delay in care-seeking was associated with age, lower education and being a current smoker. TB awareness campaigns targeting these population groups may improve care-seeking behavior and reduce community TB transmission.

Geographic mobility and time to seeking care among people with TB in Limpopo, South Africa

SETTING: Human mobility contributes to the spread of infectious diseases. South Africa has a long history of internal labor migration and a high burden of TB.METHODS: People newly diagnosed with TB in the Vhembe and Waterberg Districts of Limpopo answered a questionnaire regarding geographic movement over the past year. Participants were classified as 'highly mobile' (spending more than 30 nights at a residence other than their primary residence in the past year, or being ≥250 km from their primary residence at the time of the interview) or 'less mobile'. We explored associations between sociodemographic characteristics and high mobility, and between mobility and time to presentation at a clinic.RESULTS: Of the 717 participants included, 185 (25.7%) were classified as 'highly mobile'. Factors associated with high mobility included living with someone outside of Limpopo Province, HIV-positive status (men only), and current smoking (men only). Highly mobile individuals had similar care-seeking behavior as less mobile individuals (adjusted time ratio 0.9, 95% CI 0.6-1.2, P = 0.304)CONCLUSION: Highly mobile people with TB in Limpopo Province were more likely to live with people from outside the province, smoke, and have HIV. These patients had similar delays in seeking care as less mobile individuals.

A variance components factor model for genetic association studies: a Bayesian analysis

Studies of gene-trait associations for complex diseases often involve multiple traits that may vary by genotype groups or patterns. Such traits are usually manifestations of lower-dimensional latent factors or disease syndromes. We illustrate the use of a variance components factor (VCF) model to model the association between multiple traits and genotype groups as well as any other existing patient-level covariates. This model characterizes the correlations between traits as underlying latent factors that can be used in clinical decision-making. We apply it within the Bayesian framework and provide a straightforward implementation using the WinBUGS software. The VCF model is illustrated with simulated data and an example that comprises changes in plasma lipid measurements of patients who were treated with statins to lower low-density lipoprotein cholesterol, and polymorphisms from the apolipoprotein-E gene. The simulation shows that this model clearly characterizes existing multiple trait manifestations across genotype groups where individuals' group assignments are fully observed or can be deduced from the observed data. It also allows one to investigate covariate by genotype group interactions that may explain the variability in the traits. The flexibility to characterize such multiple trait manifestations makes the VCF model more desirable than the univariate variance components model, which is applied to each trait separately. The Bayesian framework offers a flexible approach that allows one to incorporate prior information.

Design sequences for sensory studies: achieving balance for carry-over and position effects

In sequences of human sensory assessments, the response toa stimulus may be influenced by previous stimuli. When investigating this phenomenon experimentally with several types or levels of stimulus, it is useful to have treatment sequences which are balanced for first-order carry-over effects. The requirement of balance for each experimental participant leads us to consider sequences of n symbols comprising an initial symbol followed by n ;blocks' each containing a permutation of the symbols. These sequences are designed to include all n (2) ordered pairs of symbols once each, and to have treatment and sequence position effects which are approximately or thogonal. Such sequences were suggested by Finney and Outhwaite (1956), who were able to find examples for particular values of n. We describe and illustrate acomputer algorithm for systematically enumerating the sequences for those values of n for which they exist. Criteria are proposed for choosing between the sequences according to the nearness to orthogonality of their treatment and position effects.