Modelling the impact of migration on the HIV epidemic in South Africa

Estimating contact network properties by integrating multiple data sources associated with infectious diseases

To effectively mitigate the spread of communicable diseases, it is necessary to understand the interactions that enable disease transmission among individuals in a population; we refer to the set of these interactions as a contact network. The structure of the contact network can have profound effects on both the spread of infectious diseases and the effectiveness of control programs. Therefore, understanding the contact network permits more efficient use of resources. Measuring the structure of the network, however, is a challenging problem. We present a Bayesian approach to integrate multiple data sources associated with the transmission of infectious diseases to more precisely and accurately estimate important properties of the contact network. An important aspect of the approach is the use of the congruence class models for networks. We conduct simulation studies modeling pathogens resembling SARS-CoV-2 and HIV to assess the method; subsequently, we apply our approach to HIV data from the University of California San Diego Primary Infection Resource Consortium. Based on simulation studies, we demonstrate that the integration of epidemiological and viral genetic data with risk behavior survey data can lead to large decreases in mean squared error (MSE) in contact network estimates compared to estimates based strictly on risk behavior information. This decrease in MSE is present even in settings where the risk behavior surveys contain measurement error. Through these simulations, we also highlight certain settings where the approach does not improve MSE.

Post-migration emotional well-being among Black South Africans

Internal migration has been an institutionalized part of life for Black South Africans from the 1800s, when men left their rural homes to work in mines, through apartheid and into the present. Like other settings in the Global South, we know surprisingly little about the emotional well-being of migrants, especially in sub-Saharan African contexts. We investigate changes in the emotional well-being of 2281 working-age Black South Africans after migration, drawing on four waves of data, from 2008 to 2015, from the nationally representative National Income Dynamics Study. Fixed-effects regressions show that migrants exhibit changes in life satisfaction as well as proclivity towards depression but that these outcomes vary by distance of move and type of move-moving within or between provinces. As South Africa's health policies expand beyond addressing infectious diseases, it is important to consider mental health particularly of those who face the necessity of migration to sustain a livelihood.

Industrial mining and HIV risk: evidence from 39 mine openings across 16 countries in sub-Saharan Africa

OBJECTIVES

The aim of this study was to assess the impact of natural resource extraction projects on HIV transmission risks in local communities in sub-Saharan Africa.

DESIGN

Difference-in-differences design using repeated cross-sectional data from around newly opened mines.

METHODS

We combined data on mine openings with HIV data from the Demographic and Health Surveys (DHS). Using logistic regression models, we compared HIV-related indicators between mining (i.e. up to 10 km distance from the mine) and comparison (i.e. 10-50 km) areas before and after mine opening to identify their impact on HIV prevalence, sexual behavior and HIV knowledge.

RESULTS

A total of 33 086 individuals across 39 mine openings were analyzed. Adjusting for baseline differences and temporal trends in the study regions, mine opening increased the odds of HIV infection almost two-fold [odds ratio (OR): 1.93, 95% confidence interval (CI): 1.19-3.14]. Strongest effects were seen in high-prevalence countries and in the 20-29 years age group. In mining communities around operational mines, there was a tendency towards lower HIV knowledge (OR: 0.81, 95% CI: 0.63-1.04). New mine openings increased the odds of risky sexual behaviors, such as having multiple sex partners (OR: 1.61, 95% CI: 1.02-2.55), high-risk sexual partners (OR: 1.45, 95% CI: 1.03-2.05) and unprotected sex with high-risk partners (OR: 1.77, 95% CI: 1.18-2.67).

CONCLUSION

The findings suggest that in our sample of households surrounding industrial mines, HIV infection risks substantially increase upon mine opening. Existing strategies for addressing mining-related risks for HIV transmission seem to be insufficient. Further efforts for mitigating and monitoring impacts of mines are needed.

Modelling the geographical spread of HIV among MSM in Guangdong, China: a metapopulation model considering the impact of pre-exposure prophylaxis

Men who have sex with men (MSM) make up the majority of new human immunodeficiency virus (HIV) diagnoses among young people in China. Understanding HIV transmission dynamics among the MSM population is, therefore, crucial for the control and prevention of HIV infections, especially for some newly reported genotypes of HIV. This study presents a metapopulation model considering the impact of pre-exposure prophylaxis (PrEP) to investigate the geographical spread of a hypothetically new genotype of HIV among MSM in Guangdong, China. We use multiple data sources to construct this model to characterize the behavioural dynamics underlying the spread of HIV within and between 21 prefecture-level cities (i.e. Guangzhou, Shenzhen, Foshan, etc.) in Guangdong province: the online social network via a gay social networking app, the offline human mobility network via the Baidu mobility website, and self-reported sexual behaviours among MSM. Results show that PrEP initiation exponentially delays the occurrence of the virus for the rest of the cities transmitted from the initial outbreak city; hubs on the movement network, such as Guangzhou, Shenzhen, and Foshan are at a higher risk of 'earliest' exposure to the new HIV genotype; most cities acquire the virus directly from the initial outbreak city while others acquire the virus from cities that are not initial outbreak locations and have relatively high betweenness centralities, such as Guangzhou, Shenzhen and Shantou. This study provides insights in predicting the geographical spread of a new genotype of HIV among an MSM population from different regions and assessing the importance of prefecture-level cities in the control and prevention of HIV in Guangdong province. This article is part of the theme issue 'Data science approach to infectious disease surveillance'.

Analysing the impact of migration on HIV/AIDS cases using epidemiological modelling to guide policy makers

In this paper, we present the impact of migration on the spread of HIV and AIDS cases. A simple model for HIV and AIDS that incorporates migration and addresses its contributions to the spread of HIV and AIDS cases was constructed. The model was calibrated to HIV and AIDS incidence data from Malaysia. We explore the use of Markov chain Monte Carlo (MCMC) simulation method to estimate uncertainty in all the unknown parameters incorporated in our proposed model. Among the migrant population, 1.5572e-01 were susceptible to HIV transmission, which constituted 67,801 migrants. A proportion of migrants, 6.3773e-04, were estimated to be HIV infected, constituting 278 migrants. There were 72 (per 10,000) migrants estimated to have had AIDS, representing a proportion of 1.6611e-08. The result suggests that the disease-free steady state was unstable since the estimated basic reproduction number R0 was 2.0906 and 2.3322 for the models without and with migration, respectively. This is not a good indicator from the public health point of view, as the aim is to stabilize the epidemic at the disease-free equilibrium. The advantage of introduction of migration to the simple model validated the true R0 and the transmission rate β associated with HIV and AIDS epidemic disease in Malaysia. It also indicates an approximately 12 percentage points increase in the rate of HIV infection with migration.

Messaging matters: achieving equity in the HIV response through public health communication

Public health messages shape how the world understands the HIV epidemic. Considerable inequalities remain in HIV care continuum indicators by subpopulation and geography (eg, highest infection and mortality burden among men who have sex with men and people who live in sub-Saharan Africa). Health equity-focused approaches are necessary in this next decade to close gaps in the HIV epidemic. Between 1981 and 1989, HIV messages triggered fear and victim blaming, and highlighted behaviours of a few marginalised groups as deviant. Between 1990 and 1999, messages signalled that HIV was a growing challenge for the world and required multisector approaches that addressed structural drivers of inequality. Between 2000 and 2009, messages highlighted universal testing, while advances in HIV testing made these messages easier for individuals to respond to than in previous decades. Currently, messages signal that ending HIV is possible, people can live productive lives with HIV, and transmission to people without HIV can be eliminated. Public health messaging about the HIV epidemic has evolved substantially over the past 40 years. Future HIV messaging should be driven by health equity principles that include an increased representation of key populations in message design and dissemination, transparency of funding, and communicating any impact that campaigns have had on closing health inequalities.

Assessment of spatial mobility among young men who have sex with men within and across high HIV prevalence neighborhoods in New York city: The P18 neighborhood study

The purpose of this study was to examine and quantify spatial mobility among HIV-negative young men who have sex with men (YMSM) within and across high prevalence HIV neighborhoods in New York City (NYC). We completed an analysis with global positioning system (GPS) and survey data to quantify spatial mobility for participants enrolled in the P18 Neighborhood Study (analytic n = 211; 83.4%). Spatial mobility was documented with self-reported survey data and objective GPS data, which was uncorrelated. Nearly one-quarter of participants (26.1%) said that they consider the neighborhood in which they currently live to differ from the neighborhood in which they had sex most frequently. In addition, 62.9% of participants' GPS points were recorded in NYC ZIP Code Tabulation Areas within the highest quartile of HIV prevalence. Future studies of YMSM populations should be conducted to examine how environments beyond the residential neighborhood can influence sexual health, which may guide HIV prevention services.

Associations of spatial mobility with sexual risk behaviors among young men who have sex with men in New York City: A global positioning system (GPS) study

Spatial contexts and spatial mobility are important factors of the HIV epidemic and sexually transmitted infections. Using global positioning system (GPS) devices, we examined the associations of objectively measured spatial mobility with sexual risk behaviors among gay, bisexual and other men who have sex with men (MSM) in New York City. This observational study included a subgroup of 253 HIV-negative MSM from the Project 18 Cohort Study, who participated in the GPS monitoring sub-study. Spatial mobility was measured as (1) distance traveled and (2) activity space size defined as daily path area during 2-week of GPS tracking. We examined the associations of these measures with numbers of male sexual partners and condomless anal intercourse (CAI) acts during last six months using quasi-Poisson models, adjusting for socio-demographics. Results demonstrated that spatial mobility was positively associated with sexual risk behaviors, for example, with CAI (incidence rate ratio [IRR] = 1.01 for a 10 km increase in distance traveled and IRR = 1.04 for a 1 km² increase in 50 m-buffer activity space size). Our findings may enhance the understanding of spatial contexts of HIV risk. Future studies should be conducted to examine the mechanisms for the associations between spatial mobility behaviors with sexual risk behaviors as well as the influence of neighborhood characteristics in various neighborhood contexts, which may guide the place-based HIV prevention services.

"Left behind": why implementing migration-aware responses to HIV for migrant farm workers is a priority for South Africa

Like many other countries, South Africa (SA) has committed to the Sustainable Development Goals that aim to "leave no-one behind", in efforts towards universal health coverage, and meeting the UNAIDS 90-90-90 targets through the implementation of universal test and treat (UTT) interventions. SA is associated with high levels of international and internal migration that, in certain contexts, are known to (1) increase the risk of acquiring HIV and (2) present challenges to HIV treatment access and continuity. Despite this, migration and mobility are not adequately considered in responses to HIV. As SA rolls out UTT programmes and antiretroviral treatment as prevention (TasP) interventions, including pre-exposure prophylaxis (PreP), there is an urgent need to ensure that these are migration-aware and mobility-competent. In SA, a key population that experiences a disproportionate HIV burden is international migrant farm workers living and working on commercial farms along the border with Zimbabwe. In this article, a social determinants of health approach is applied to explore the context within which this population struggles to access positive determinants of health, including the public health care system, and the implications of this for HIV programming. It is argued that, unless policies and programming become migration-aware and mobility-competent, UTT and TasP interventions will struggle to address the high burden of HIV among this population and, as a result, progress towards global health targets will be limited.

Using lattice SIS epidemiological model with clustered treatment to investigate epidemic control

In epidemic control, how the size of treatment blocks influences the disease is a very interesting problem. Here, we construct an SIS model with spatially clustered treatment blocks using cellular automata and pair approximation to investigate the disease control and optimal arrangement of treatment blocks. On a same treatment intensity, the treatment blocks are built randomly and the individuals in the treatment blocks are cured in the next interval. The migration and neighboring structures are also considered in this model. We find that the size of treatment blocks will influence the control of disease. The bigger size of treatment blocks is more effective in epidemic control. The results obtained by lattice simulations and pair approximation respectively are consistent. On the same treatment arrange, higher migration rate has completely different influence on the epidemic depending on different neighboring structures. Besides, in different neighboring structures, both infected and susceptible populations will get clustered under the treatment blocks. Meanwhile, the neighboring structures can influence the degree of aggregation and the bigger treatment blocks can promote the aggregation compared to the smaller ones. The results here are significant for the control of epidemic diseases, especially when available medical resources are limited.

Economic evaluation studies in the field of HIV/AIDS: bibliometric analysis on research development and scopes (GAPRESEARCH)

Background

The rapid decrease in international funding for HIV/AIDS has been challenging for many nations to effectively mobilize and allocate their limited resources for HIV/AIDS programs. Economic evaluations can help inform decisions and strategic planning. This study aims to examine the trends and patterns in economic evaluation studies in the field of HIV/AIDS and determine their research landscapes.

Methods

Using the Web of Science databases, we synthesized the number of papers and citations on HIV/AIDS and economic evaluation from 1990 to 2017. Collaborations between authors and countries, networks of keywords and research topics were visualized using frequency of co-occurrence and Jaccards’ similarity index. A Latent Dirichlet Allocation (LDA) analysis to categorize papers into different topics/themes.

Results

A total of 372 economic evaluation papers were selected, including 351 cost-effectiveness analyses (CEA), 11 cost-utility analyses (CUA), 12 cost-benefit analyses (CBA). The growth of publications, their citations and usages have increased remarkably over the years. Major research topics in economic evaluation studies consisted of antiretroviral therapy (ART) initiation and treatment; drug use prevention interventions and prevention of mother-to-child transmission interventions. Moreover, lack of contextualized evidence was found in specific settings with high burden HIV epidemics, as well as emerging most-at-risk populations such as trans-genders or migrants.

Conclusion

This study highlights the knowledge and geographical discrepancies in HIV/AIDS economic evaluation literature. Future research directions are also informed for advancing economic evaluation in HIV/AIDS research.

The future of a partially effective HIV vaccine: assessing limitations at the population level

OBJECTIVES

Mathematical models have unanimously predicted that a first-generation HIV vaccine would be useful and cost-effective to roll out, but that its overall impact would be insufficient to reverse the epidemic. Here, we explore what factors contribute most to limiting the impact of such a vaccine.

METHODS

Ranging from a theoretical ideal to a more realistic regimen, mirroring the one used in the currently ongoing trial in South Africa (HVTN 702), we model a nested hierarchy of vaccine attributes such as speed of scale-up, efficacy, durability, and return rates for booster doses.

RESULTS

The predominant reasons leading to a substantial loss of vaccine impact on the HIV epidemic are the time required to scale up mass vaccination, limited durability, and waning of efficacy.

CONCLUSIONS

A first-generation partially effective vaccine would primarily serve as an intermediate milestone, furnishing correlates of immunity and platforms that could serve to accelerate future development of a highly effective, durable, and scalable next-generation vaccine capable of reversing the HIV epidemic.

Those Who Don't Return: Improving Efforts to Address Tuberculosis Among Former Miners in Southern Africa

Despite increasing awareness regarding the role of oscillating migration in the mining industry as a major driving force in the spread of tuberculosis (TB) throughout southern Africa, very little work has focused on the historical and contextual factors which may contribute to former migrant miners' present-day risk of TB. Most research regarding migration-related and occupational influences on TB has been done on current miners still employed by the mining industry. Through both a historical and contemporary lens, this paper explores and elucidates the need to address the TB epidemic among former migrant mine workers and provides considerations to improve current interventions among this critical population.

Pattern of sexual behavior among people in a rural area of Bihar: A qualitative study on wives of migrant workers

Background:

Population mobility and migration are important processes of human life. It affects broad range of sociocultural parameters. Mobility increases personal interaction and exposure to sexual partners from high-risk group. Although traditional Indian value prohibits premarital or extramarital sexual activities, but this aspect has not been explored in migrant workers.

Methods:

It was a qualitative study based on indepth interview of participants. The participants were wives of migrant workers. Indepth interviews were conducted by two female field interviewers recruited for the study. A total of 24 study subjects were recruited for the study. An indepth interview guide was prepared which mainly focused on sexual behavior, including premarital, marital, and extramarital, quality of marital relationship, gender roles, peer networks, substance abuse, work-related activities, etc., The transcripts were analyzed in NVIVO and themes were generated.

Results:

The premarital sex was more common in boys than girls. It is more common in the same age group and has increased in the recent years. Various reasons were cited in relation to premarital sex in rural areas like love affair, delayed marriage, watching bad movies, bad company, allurement for gifts money, etc., Some women had opinion that males belonging to affluent and powerful families had tendency to enjoy sex with other women within and outside village. The major themes which emerged from the study were the sexual activity, type of sexual partners, reasons for multiple sexual partner, and risky and nonrisky sexual activity.

Conclusion:

The findings of the study provided insights to design and conduct a larger and more representative quantitative study among the wives of migrant workers to understand the dynamic combination of biomedical, behavioral, and sociocultural factors that may influence transmission of infection within marriage.

Association between internal migration and epidemic dynamics: an analysis of cause-specific mortality in Kenya and South Africa using health and demographic surveillance data

BACKGROUND

Many low- and middle-income countries are facing a double burden of disease with persisting high levels of infectious disease, and an increasing prevalence of non-communicable disease (NCD). Within these settings, complex processes and transitions concerning health and population are underway, altering population dynamics and patterns of disease. Understanding the mechanisms through which changing socioeconomic and environmental contexts may influence health is central to developing appropriate public health policy. Migration, which involves a change in environment and health exposure, is one such mechanism.

METHODS

This study uses Competing Risk Models to examine the relationship between internal migration and premature mortality from AIDS/TB and NCDs. The analysis employs 9 to 14 years of longitudinal data from four Health and Demographic Surveillance Systems (HDSS) of the INDEPTH Network located in Kenya and South Africa (populations ranging from 71 to 223 thousand). The study tests whether the mortality of migrants converges to that of non-migrants over the period of observation, controlling for age, sex and education level.

RESULTS

In all four HDSS, AIDS/TB has a strong influence on overall deaths. However, in all sites the probability of premature death (45q15) due to AIDS/TB is declining in recent periods, having exceeded 0.39 in the South African sites and 0.18 in the Kenyan sites in earlier years. In general, the migration effect presents similar patterns in relation to both AIDS/TB and NCD mortality, and shows a migrant mortality disadvantage with no convergence between migrants and non-migrants over the period of observation. Return migrants to the Agincourt HDSS (South Africa) are on average four times more likely to die of AIDS/TB or NCDs than are non-migrants. In the Africa Health Research Institute (South Africa) female return migrants have approximately twice the risk of dying from AIDS/TB from the year 2004 onwards, while there is a divergence to higher AIDS/TB mortality risk amongst female migrants to the Nairobi HDSS from 2010.

CONCLUSION

Results suggest that structural socioeconomic issues, rather than epidemic dynamics are likely to be associated with differences in mortality risk by migrant status. Interventions aimed at improving recent migrant's access to treatment may mitigate risk.

Male Migration, Women Left Behind, and Sexually Transmitted Diseases in Armenia

The effect of male circular labor migration on risks of sexually transmitted diseases (STDs) among women left behind has not been well studied. Our study examines this effect using data from a survey of 1,240 married women in rural Armenia, where international male labor migration has traditionally been very common. A multivariate comparison of women married to migrants and women married to non-migrants finds that the former, ceteris paribus, reported more STD symptoms, on average, and were more likely to report diagnosed STDs than the latter. However, in the case of STD symptoms, this effect is moderated by household income, as the predicted number of STD symptoms reported by migrants’ wives increases as income rises. The findings illustrate the complex tradeoffs that migration entails for left-behind women and are interpreted in the context of the literature on gender, migration, and STDs.

Tracking external introductions of HIV using phylodynamics reveals a major source of infections in rural KwaZulu-Natal, South Africa

Despite increasing access to antiretrovirals, HIV incidence in rural KwaZulu-Natal remains among the highest ever reported in Africa. While many epidemiological factors have been invoked to explain such high incidence, widespread human mobility and viral movement suggest that transmission between communities may be a major source of new infections. High cross-community transmission rates call into question how effective increasing the coverage of antiretroviral therapy locally will be at preventing new infections, especially if many new cases arise from external introductions. To help address this question, we use a phylodynamic model to reconstruct epidemic dynamics and estimate the relative contribution of local transmission versus external introductions to overall incidence in KwaZulu-Natal from HIV-1 phylogenies. By comparing our results with population-based surveillance data, we show that we can reliably estimate incidence from viral phylogenies once viral movement in and out of the local population is accounted for. Our analysis reveals that early epidemic dynamics were largely driven by external introductions. More recently, we estimate that 35 per cent (95% confidence interval: 20-60%) of new infections arise from external introductions. These results highlight the growing need to consider larger-scale regional transmission dynamics when designing and testing prevention strategies.

Modelling the human immunodeficiency virus (HIV) epidemic: A review of the substance and role of models in South Africa

We review key mathematical models of the South African human immunodeficiency virus (HIV) epidemic from the early 1990s onwards. In our descriptions, we sometimes differentiate between the concepts of a model world and its mathematical or computational implementation. The model world is the conceptual realm in which we explicitly declare the rules – usually some simplification of ‘real world’ processes as we understand them. Computing details of informative scenarios in these model worlds is a task requiring specialist knowledge, but all other aspects of the modelling process, from describing the model world to identifying the scenarios and interpreting model outputs, should be understandable to anyone with an interest in the epidemic.

A Review of Research on Health Outcomes for Workers, Home and Host Communities of Population Mobility Associated with Extractive Industries

With a growing awareness of the association between extractive industries, the nature of work in remote locations, population mobility and health status, there is a need to advance an evidence-based approach to ensuring the health of migrant and mobile populations, and the home and host communities with whom they interact. Through a narrative synthesis of peer-reviewed and grey literature, this review examines what is known, and the nature of research activity concerning the range of health impacts determined by the social conditions inherent with population mobility alongside mining and extractive industries; and the extent to which health outcomes impact on workers, and home and host communities. While much of the literature reviewed in the study considered health in a traditional disease or illness based approach, it is clear that many risk factors for the health of mobile workers in the sector reflect broader social determinants. To support the mitigation of individual and population vulnerability to infectious disease endemics, consideration of both the etiology and the social conditions that give rise to adverse health outcomes is required, including an improvement to workers' living conditions, the expansion of diagnostic and medical services, and an approach that ensures the right to health for mobile populations. To further improve upon the rich body of research, resources are required to implement robust data collection including epidemiological surveillance, outbreak monitoring and investigation, and the long term tracking of standardized health information at both origin locations and destination communities.

Geographic mobility and potential bridging for sexually transmitted infections in Agbogbloshie, Ghana

Short-term mobility can significantly influence the spread of infectious disease. In order for mobile individuals to geographically spread sexually transmitted infections (STIs), individuals must engage in sexual acts with different partners in two places within a short time. In this study, we considered the potential of mobile individuals as bridge populations - individuals who link otherwise disconnected sexual networks and contributed to ongoing STI transmission. Using monthly retrospective panel data, we examined associations between short-term mobility and sexual partner concurrency in Agbogbloshie, Ghana. We also examined bridging by the location of sex acts and the location of sexual partners in concurrent triads, and whether mobile individuals from our sample were more likely to be members of geographic bridging triads. Although reported rates of sexual partnership concurrency were much higher for men compared to women, mobility was only associated with increased concurrency for women. Additionally, this association held for middle-distance mobility and short-duration trips for women. Taking into account the location of sex acts and the location of sexual partners, about 22% of men (21.7% and 22.4% for mobile and non-mobile men, respectively) and only 3% of women (1.4% and 3.3% for mobile and non-mobile women, respectively) were potential bridges for STIs over the last year. Our results highlight the gendered nature of mobility and sexual risk behavior, reflecting the normative social context that encourages women to conceal certain types of sexual behavior.

Social Disequilibrium and the Risk of HIV Acquisition: A Multilevel Study in Rural KwaZulu-Natal Province, South Africa

BACKGROUND

Few population-based multilevel studies have quantified the risks that social context poses in rural communities with high HIV incidence across South Africa. We investigated the individual, social, and community challenges to HIV acquisition risk in areas with high and low incidence of HIV infection (hotspots/coldspots).

METHODS

The cohort (N = 17,376) included all HIV-negative adults enrolled in a population-based HIV surveillance study from 2004 to 2015 in a rural South African community with large labor migrancy. Multilevel survival models were fitted to examine the social determinants (ie, neighborhood migration intensity), community traits (ie, HIV prevalence), and individual determinants of HIV acquisition risk in identified hotspots/coldspots.

RESULTS

The HIV acquisition risk (adjusted hazard ratio [aHR] = 1.05, 95% confidence interval [CI]: 1.01 to 1.09) was greater in hotspots with higher neighborhood migration intensity among men. In women, higher neighborhood migration intensity (aHR = 1.02, 95% CI: 1.01 to 1.02) was associated with a greater HIV acquisition risk, irrespective of whether they lived in hotspot/coldspot communities. HIV acquisition risk was greater in communities with a higher prevalence of HIV in both men (aHR = 1.07, 95% CI: 1.03 to 1.12) and women (aHR = 1.03, 95% CI: 1.01 to 1.05), irrespective of hotspot/coldspot locations.

CONCLUSION

HIV acquisition risk was strongly influenced by gender (ie, young women), behavior (ie, sexual debut, contraception, circumcision), and social determinants. Certain challenges (ie, community disease prevalence) for HIV acquisition risk impacted both sexes, regardless of residence in hotspot/coldspot communities, whereas social determinants (ie, neighborhood migration intensity) were pronounced in hotspots among men. Future intervention scale-up requires addressing the social context that contributes to HIV acquisition risk in rural areas with high migration.

A Novel Modeling Approach for Estimating Patterns of Migration into and out of San Francisco by HIV Status and Race among Men Who Have Sex with Men

In the early 1980s, men who have sex with men (MSM) in San Francisco were one of the first populations to be affected by the human immunodeficiency virus (HIV) epidemic, and they continue to bear a heavy HIV burden. Once a rapidly fatal disease, survival with HIV improved drastically following the introduction of combination antiretroviral therapy in 1996. As a result, the ability of HIV-positive persons to move into and out of San Francisco has increased due to lengthened survival. Although there is a high level of migration among the general US population and among HIV-positive persons in San Francisco, in- and out-migration patterns of MSM in San Francisco have, to our knowledge, never been described. Understanding migration patterns by HIV serostatus is crucial in determining how migration could influence both HIV transmission dynamics and estimates of the HIV prevalence and incidence. In this article, we describe methods, results, and implications of a novel approach for indirect estimation of in- and out-migration patterns, and consequently population size, of MSM by HIV serostatus and race in San Francisco. The results suggest that the overall MSM population and all the MSM subpopulations studied decreased in size from 2006 to 2014. Further, there were differences in migration patterns by race and by HIV serostatus. The modeling methods outlined can be applied by others to determine how migration patterns contribute to HIV-positive population size and output from these models can be used in a transmission model to better understand how migration can impact HIV transmission.

Differences between migrants and Spanish-born population through the HIV care cascade, Catalonia: an analysis using multiple data sources

Migrants are considered a key group at risk for HIV infection. This study describes differences between migrants and the Spanish-born population as they progress through the HIV care cascade in Catalonia, Spain. This study found that among people reached by prevention activities, migrants had a higher number of barriers to access HIV testing services than Spanish-born people, driven primarily by shared risk factors. Between 2001 and 2013, 9829 new HIV diagnoses were reported in Catalonia, the proportion of migrants increasing from 24% in 2001 to 41% in 2013. Compared with Spanish-born people, migrants had a higher proportion of women at diagnosis (24·6% vs. 16·7%), and were younger (median age of 33 vs. 37). The most frequent at-risk population was MSM (men who have sex with men) in both migrants and Spanish-born people, (40% and 43%, respectively), although there were significant differences by region of origin. People from sub-Saharan Africa had the highest proportion of late diagnosis (63·7%). Compared with the Spanish-born population, migrants on follow-up had a lower proportion of people on antiretroviral therapy (ART) (93·7% vs. 90·8%, P < 0·001) and with viral suppression (87·2% vs. 82·9%, P < 0·001). Migrants have higher number of barriers to access HIV testing services, lower retention rates and proportions on ART as compared with Spanish-born people, these differences not being uniform between migrants from different regions.

Biological aspects of human migration and mobility

This paper reviews how migration, both geographical and social, impacts on variation in some human biological traits. Migration and mobility are considered in relation to anthropometric traits and indices, psychometric traits, health, disease and nutrition, temperature regulation and metabolism, mental health and gene flow. It is well known that migration is important in disease transmission but, as this paper demonstrates, migration can have both positive and negative impacts on both donor and recipient populations for a wide range of human traits.

A qualitative study of migrant-related stressors, psychosocial outcomes and HIV risk behaviour among truck drivers in Zambia

Truck drivers are part of mobile populations which have been noted as a key population at risk of HIV in Zambia. This study was aimed at: (1) determining potentially traumatic events (PTEs), labour migrant-related stressors, psychosocial problems and HIV risk behaviours among truck drivers in Zambia; and (2) examining the relationship between PTEs, migrant-related stressors, psychosocial outcomes and HIV sexual risk behaviour among truck drivers in Zambia. We conducted 15 semi-structured interviews with purposively sampled male truck drivers at trucking companies in Lusaka, Zambia. Findings indicate that truck drivers experience multiple stressors and potentially traumatic incidences, including delays and long waiting hours at borders, exposure to crime and violence, poverty, stress related to resisting temptation of sexual interactions with sex workers or migrant women, and job-related safety concerns. Multiple psychosocial problems such as intimate partner violence, loneliness, anxiety and depression-like symptoms were noted. Transactional sex, coupled with inconsistent condom use, were identified as HIV sexual risk behaviours. Findings suggest the critical need to develop HIV-prevention interventions which account for mobility, potentially traumatic events, psychosocial problems, and the extreme fear of HIV testing among this key population.

Male labor migration, patriarchy, and the awareness-behavior gap: HIV risks and prevention among migrants' wives in Armenia

Unlike in most of the world, HIV incidence in the former Soviet Union continues to rise. While international labor migration has been identified as a potentially important contributor to this trend, most attention has been focused on risks of male migrants themselves. This study uses recent household survey data to examine HIV-related perceptions and actions of migrants' left-behind wives in Armenia. Multivariate logistic regression analyses show that migrants' wives are significantly more likely to suspect their husbands of extramarital sex than are non-migrants' wives. The analyses detect greater worries about HIV infection and a higher likelihood of spousal communication on HIV matters among migrants' wives, compared to non-migrants' wives, but these differences are largely explained by the suspicion of husband's extramarital sex. Finally, no difference between the two categories of women in the probability of consistent condom use with husbands is found. These findings are interpreted within the context of patriarchal culture and unequal gender relations in Armenian society as they are further reinforced by male migration. Implications of these findings for policies to increase women's awareness of HIV risks associated with migration and their ability to reduce those risks are discussed.

Effects of In-country and Cross-Border Mobility on Condom Use Among Transgender Women (hijras) in Bangladesh: A Cross-Sectional Study

In Bangladesh transgender women (hijras) are thought to be highly mobile that may be an impediment to condom use. This cross-sectional study was conducted to determine the extent of mobility of hijras, in-country and cross-border, and whether mobility affects condom use in anal intercourse. Hijras ≥15 years of age, receiving services from the Global Fund supported HIV prevention program were enrolled. A behavioral questionnaire was administered and blood was tested for antibodies to HIV and syphilis. Of 889 hijras sampled, 41.3 % never traveled, 26.4 % traveled in-country and 32.3 % crossed the border in the last year. HIV and active syphilis was at 0.8 and 1.8 % respectively. Among hijras who crossed the border condom use was less likely in last anal intercourse (AOR 0.68; 95 % CI 0.48-0.96), and consistently with new (AOR 0.59; 95 % CI 0.34-1.01) and regular clients (AOR 0.45; 95 % CI 0.27-0.76) in the last week. This study concludes that in Bangladesh hijras are highly mobile and cross-border mobility negatively affects condom use.

Optimum resource allocation to reduce HIV incidence across sub-Saharan Africa: a mathematical modelling study

BACKGROUND

Advances in HIV prevention methods offer promise to accelerate declines in incidence, but how these methods can be deployed to have the best effect on the heterogeneous landscape and drivers of the pandemic remains unclear. We postulated that use of epidemic heterogeneity to inform the allocation of resources for combination HIV prevention could enhance the impact of HIV funding across sub-Saharan Africa.

METHODS

We developed a compartmental mathematical model of HIV transmission and disease progression by risk group to subnational resolution in 18 countries, capturing 80% of the adult HIV burden in sub-Saharan Africa. Adults aged 15-49 years were grouped by risk of HIV acquisition and transmission, and those older than 50 years were assumed to have negligible risk. For each top-level administrative division, we calibrated the model to historical data for HIV prevalence, sexual behaviours, treatment scale-up, and demographics. We then evaluated four strategies for allocation of prevention funding over a 15 year period from 2016 to 2030, which exploited epidemic differences between subnational regions to varying degrees.

FINDINGS

For a $US20 billion representative expenditure over the 15 year period, scale-up of prevention along present funding channels could avert 5·3 million infections relative to no scale-up. Prioritisation of key populations could avert 3·7 million more infections than present funding channels, and additional prioritisation by within-country geography could avert 400 000 more infections. Removal of national constraints could avert a further 600 000 infections. Risk prioritisation has greater marginal impact than geographical prioritisation across multiple expenditure levels. However, targeting by both risk and geography is best for total impact and could achieve gains of up to three times more than present channels. A shift from the present pattern to the optimum pattern would rebalance resources towards more cost-effective interventions and emerging epidemics.

INTERPRETATION

If domestic and international funders were to align strategically to build an aggregate funding pattern that is guided by the epidemiology of HIV, and particularly by the emerging understanding of local dynamics and epidemic drivers, more cost-effective and impactful HIV prevention investments could be achieved across sub-Saharan Africa.

FUNDING

The Bill & Melinda Gates Foundation.

Migration and HIV infection in Malawi

OBJECTIVE

To evaluate the assumption that moving heightens HIV infection by examining the time-order between migration and HIV infection and investigate differences in HIV infection by migration destination and permanence.

METHODS

We employ four waves of longitudinal data (2004-2010) for 4265 men and women from a household-based study in rural Malawi and a follow-up of migrants (2013). Using these data, we examine HIV status prior to migration. Migrants are disaggregated by destination (rural, town, and urban) and duration (return and permanent); all compared with individuals who consistently resided in the rural origin ('nonmigrants').

RESULTS

HIV-positive individuals have significantly greater odds of migration than those who are HIV negative [odds ratio 2.75; 95% confidence interval (CI) 1.89-4.01]. Being HIV positive significantly increases the relative risk (RR) that respondent will be a rural-urban migrant [RR ratio (RRR) 6.28; 95% CI 1.77-22.26), rural-town migrant (RRR 3.62; 95% CI 1.24-10.54), and a rural-rural migrant (RRR 4.09; 95% CI 1.68-9.97), instead of a nonmigrant. Being HIV positive significantly increases the RR that a respondent will move and return to the village of origin (RRR 2.58; 95% CI 1.82-3.66) and become a permanent migrant (RRR 3.21; 95% CI 1.77-5.82) instead of not migrating.

CONCLUSION

HIV-positive status has a profound impact on mobility: HIV infection leads to significantly higher mobility through all forms of migration captured in our study. These findings emphasize that migration is more than just an independent risk factor for HIV infection: greater prevalence of HIV among migrants is partly due to selection of HIV-positive individuals into migration.

Exploring the relationship between population mobility and HIV risk: Evidence from Tanzania

Migration and population mobility has long been regarded as an important structural driver of HIV. Following initial concerns regarding the spatial spread of the disease, mobile populations are viewed to engage in higher levels of risky sexual behaviours than non-mobile groups. However, beyond the case studies of mineworkers and truck drivers, the statistical evidence is inconclusive, suggesting that the relationship between mobility and risk is not well understood. This study investigated how engaging in specific livelihoods that involve mobility influences sexual behaviour and HIV risk. A qualitative research project, including focus groups and in-depth interviews with key mobile groups, was conducted in Northern Tanzania. The findings show that the patterns and conditions of moving related to the requirements of each different economic activity influence the nature of relationships that mobile groups have whilst away, how and where local sexual networks are accessed, and the practicalities of having sex. This has further implications for condom use. Risk behaviours are also shaped by local sexual norms related to transactional sex, emphasising that the roles of mobility and gender are interrelated, overlapping and difficult to disentangle.

In-Country Migration and Risk Factors for HIV Acquisition among Pregnant Women in Tijuana, Mexico

OBJECTIVE

To compare HIV prevalence and HIV acquisition risk behaviors between pregnant women residents and migrants.

DESIGN

A cross-sectional study of pregnant women of unknown HIV status seeking care at Tijuana General Hospital, Mexico.

METHODS

Pregnant women attending the labor and delivery unit or the prenatal clinic had a rapid HIV test drawn, with positive results confirmed by Western blot. Migrants were defined as women who had resided in Tijuana for less than 5 years.

RESULTS

Between 2007 and 2008, a total of 3331 pregnant women consented to participate. The HIV seroprevalence did not differ between Tijuana residents (18 of 2502, 0.72%) and migrants (3 of 829, 0.36%, P = .32). In multivariate regression analyses, HIV acquisition risk behaviors included methamphetamine use (adjusted odds ratio [OR]: 6.03, 95% confidence interval [CI]: 2.3-15.8, P < .001) and first presentation at labor (adjusted OR: 5.0, 95% CI: 1.6-15.3, P = .005), adjusted for migrant status, age, and history of sexually transmitted infections.

CONCLUSION

The overall HIV seroprevalence was 0.63% and did not differ between Tijuana residents and migrants.

Prevalence of HIV and Associated Risk Factors Among Long Distance Truck Drivers in Inchope, Mozambique, 2012

This is the first integrated biological and behavioral surveillance survey among long-distance truck drivers (LDTD) in Mozambique. Using modified time-location sampling in 2012 at a key transportation junction (Inchope), we enrolled 327 male LDTD. HIV prevalence was 15.4 % (95 % confidence interval : 11.4-19.4 %, n = 318 tested). Among HIV-positive LDTD, 83.7 % did not know their status. One-third of LDTD had never tested for HIV and three-quarters had not received free condoms, lubricants or HIV literature in the past 12 months. In that same period, 61.4 % of LDTD had at least four sexual partners and 27.1 % paid for sex. Among sexually-active LDTD, 76.5 % did not use a condom at last sex. HIV was associated (p < 0.05) with primary education or lower (AOR 2.1), residence in Mozambique (AOR 2.3) and never having tested for HIV (AOR 2.2). Our findings reveal that broader coverage of HIV prevention and comprehensive care services for LDTD are urgently needed.

Changing spatial patterns and increasing rurality of HIV prevalence in the Democratic Republic of the Congo between 2007 and 2013

The Democratic Republic of the Congo (DRC) has one of the lowest HIV prevalence in sub-Saharan Africa, estimated at 1.1% [0.9-1.3] of adults aged 15-49 in 2013 (UNAIDS). Within the 2 million km(2) country, however, there exists spatial variation in HIV prevalence, with the highest HIV prevalence observed in the large cities of Kinshasa and Lubumbashi. Globally, HIV is an increasingly rural disease, diffusing outwards from urban centers of high HIV prevalence to places where HIV was previously absent or present at very low levels. Utilizing data collected during Demographic and Health Surveillance (DHS) in 2007 and 2013 in the DRC, we sought to update the map of HIV prevalence in the DRC as well as to explore whether HIV in the DRC is an increasingly rural disease or remains confined to urban areas. Bayesian kriging and regression indicate that HIV prevalence in rural areas of the DRC is higher in 2013 than in 2007 and that increased distance to an urban area is no longer protective against HIV as it was in 2007. These findings suggest that HIV education, testing and prevention efforts need to diffuse from urban to rural areas just as HIV is doing.

Unveiling Spatial Epidemiology of HIV with Mobile Phone Data

An increasing amount of geo-referenced mobile phone data enables the identification of behavioral patterns, habits and movements of people. With this data, we can extract the knowledge potentially useful for many applications including the one tackled in this study - understanding spatial variation of epidemics. We explored the datasets collected by a cell phone service provider and linked them to spatial HIV prevalence rates estimated from publicly available surveys. For that purpose, 224 features were extracted from mobility and connectivity traces and related to the level of HIV epidemic in 50 Ivory Coast departments. By means of regression models, we evaluated predictive ability of extracted features. Several models predicted HIV prevalence that are highly correlated (>0.7) with actual values. Through contribution analysis we identified key elements that correlate with the rate of infections and could serve as a proxy for epidemic monitoring. Our findings indicate that night connectivity and activity, spatial area covered by users and overall migrations are strongly linked to HIV. By visualizing the communication and mobility flows, we strived to explain the spatial structure of epidemics. We discovered that strong ties and hubs in communication and mobility align with HIV hot spots.

Complex routes into HIV care for migrant workers: a qualitative study from north India

Migrant workers are designated a bridge population in the spread of HIV and therefore if infected, should be diagnosed and treated early. This study examined pathways to HIV diagnosis and access to care for rural-to-urban circular migrant workers and partners of migrants in northern India, identifying structural, social and individual level factors that shaped their journeys into care. We conducted a qualitative study using in-depth interviews with HIV-positive men (n = 20) and women (n = 13) with a history of circular migration, recruited from an antiretroviral therapy centre in one district of Uttar Pradesh, north India. Migrants and partners of migrants faced a complex series of obstacles to accessing HIV testing and care. Employment insecurity, lack of entitlement to sick pay or subsidised healthcare at destination and the household's economic reliance on their migration-based livelihood led many men to continue working until they became incapacitated by HIV-related morbidity. During periods of deteriorating health they often exhausted their savings on private treatments focused on symptom management, and sought HIV testing and treatment at a public hospital only following a medical or financial emergency. Wives of migrants had generally been diagnosed following their husbands' diagnosis or death, with access to testing and treatment mediated via family members. For some, a delay in disclosure of husband's HIV status led to delays in their own testing. Diagnosing and treating HIV infection early is important in slowing down the spread of the epidemic and targeting those at greatest risk should be a priority. However, despite targeted campaigns, circumstances associated with migration may prevent migrant workers and their partners from accessing testing and treatment until they become sick. The insecurity of migrant work, the dominance of private healthcare and gender differences in health-seeking behaviour delay early diagnosis and treatment initiation.

The Impact of Human Mobility on HIV Transmission in Kenya

Disease spreads as a result of people moving and coming in contact with each other. Thus the mobility patterns of individuals are crucial in understanding disease dynamics. Here we study the impact of human mobility on HIV transmission in different parts of Kenya. We build an SIR metapopulation model that incorporates the different regions within the country. We parameterise the model using census data, HIV data and mobile phone data adopted to track human mobility. We found that movement between different regions appears to have a relatively small overall effect on the total increase in HIV cases in Kenya. However, the most important consequence of movement patterns was transmission of the disease from high infection to low prevalence areas. Mobility slightly increases HIV incidence rates in regions with initially low HIV prevalences and slightly decreases incidences in regions with initially high HIV prevalence. We discuss how regional HIV models could be used in public-health planning. This paper is a first attempt to model spread of HIV using mobile phone data, and we also discuss limitations to the approach.

History and origin of the HIV-1 subtype C epidemic in South Africa and the greater southern African region

HIV has spread at an alarming rate in South Africa, making it the country with the highest number of HIV infections. Several studies have investigated the histories of HIV-1 subtype C epidemics but none have done so in the context of social and political transformation in southern Africa. There is a need to understand how these processes affects epidemics, as socio-political transformation is a common and on-going process in Africa. Here, we genotyped strains from the start of the epidemic and applied phylodynamic techniques to determine the history of the southern Africa and South African epidemic from longitudinal sampled data. The southern African epidemic's estimated dates of origin was placed around 1960 (95% HPD 1956-64), while dynamic reconstruction revealed strong growth during the 1970s and 80s. The South African epidemic has a similar origin, caused by multiple introductions from neighbouring countries, and grew exponentially during the 1980s and 90s, coinciding with socio-political changes in South Africa. These findings provide an indication as to when the epidemic started and how it has grown, while the inclusion of sequence data from the start of the epidemic provided better estimates. The epidemic have stabilized in recent years with the expansion of antiretroviral therapy.

Targeting HIV services to male migrant workers in southern Africa would not reverse generalized HIV epidemics in their home communities: a mathematical modeling analysis

Background

Migrant populations such as mine workers contributed to the spread of HIV in sub-Saharan Africa. We used a mathematical model to estimate the community-wide impact of targeting treatment and prevention to male migrants.

Methods

We augmented an individual-based network model, EMOD-HIV v0.8, to include an age-dependent propensity for males to migrate. Migrants were exposed to HIV outside their home community, but continued to participate in HIV transmission in the community during periodic visits.

Results

Migrant-targeted interventions would have been transformative in the 1980s to 1990s, but post-2015 impacts were more modest. When targetable migrants comprised 2% of adult males, workplace HIV prevention averted 3.5% of community-wide infections over 20 years. Targeted treatment averted 8.5% of all-cause deaths among migrants. When migrants comprised 10% of males, workplace prevention averted 16.2% of infections in the community, one-quarter of which were among migrants. Workplace prevention and treatment acted synergistically, averting 17.1% of community infections and 11.6% of deaths among migrants. These estimates do not include prevention of secondary spread of HIV or tuberculosis at the workplace.

Conclusions

Though cost-effective, targeting migrants cannot collapse generalized epidemics in their home communities. Such a strategy would only have been possible prior to the early 1990s. However, migrant-targeted interventions synergize with general-population expansion of HIV services.

Cultural perceptions and negotiations surrounding sexual and reproductive health among migrant and non-migrant indigenous Mexican women from Yucatán, Mexico

Information regarding sexual and reproductive health of indigenous women from Mexican sending and US receiving communities is limited. This research aims to explore the perceptions of indigenous women from US migrant receiving and Mexican migrant sending communities regarding their sexual health experiences and reproductive health practices. From January to March 2012, two key informant interviews and 31 in-depth, semi-structured interviews were conducted among women ages 18-55 in Tunkás, Yucatán and Anaheim and Inglewood, California. Women reported challenges to obtaining routine reproductive clinical care, including access to care barriers and lack of perceived power over their own sexual health. This was further compounded by migration processes and deficiencies in health care delivery systems. Socio-cultural beliefs and gendered power dynamics influence sexual and reproductive health decisions and behaviors of migrant and non-migrant women. Findings underscore existing gender-based reproductive health norms and serve to inform future transnational research and public health education to improve the health of indigenous migrant and non-migrant women in the US and Mexico.

The converging burdens of infectious and non-communicable diseases in rural-to-urban migrant Sub-Saharan African populations: a focus on HIV/AIDS, tuberculosis and cardio-metabolic diseases

Africa has the unenviable challenge of dealing with a double burden of disease: infectious diseases (IDs) such as HIV/AIDS and tuberculosis are high while non-communicable diseases (NCDs) are rapidly rising in the region. Populations with increased susceptibility to both include migrants. This review highlights the susceptibility of rural-to-urban migrants in Sub-Saharan Africa to the IDs of HIV/AIDS and tuberculosis, and to NCDs, particularly cardiovascular diseases. The disruption that occurs with migration is often accompanied by unhealthy exposures and environments. These include partaking in risky sexual practices and a subsequent greater risk for HIV infection in migrants than the general populations which contributes to the spread of the disease. Migrants frequently work and live in conditions that are poorly ventilated and overcrowded with suboptimal sanitation which increases their risk for tuberculosis. Considering that migrants have an increased risk of acquiring both HIV/AIDS and tuberculosis, and in view of the interaction between these diseases, they are likely to be at high risk for co-infection. They are also likely to facilitate the geographical spread of these infections and serve as conduits of disease dissemination to rural areas. Changes in lifestyle behaviours that accompany migration and urbanisation are exemplified primarily by shifts in physical activity and dietary patterns which promote the development of obesity, diabetes, hypertension and cardiovascular diseases. Urban living and employment is generally less physically exerting than rural routines; when migrants relocate from their rural residence they adapt to their new environment by significantly reducing their physical activity levels. Also, nutritional patterns among migrants in urban centres change rapidly with a shift to diets higher in fat, sugar and salt. Consequently, increases in weight, blood pressure and glucose levels have been reported within a year of migration. Interactions between IDs and NCDs are common; considering that migrants have an increased susceptibility to IDs and demonstrate a rapid rise in their risk for NCDs, the concurrent prevalence of both is likely in this population. There is a need for a combined strategy to combat IDs and NCDs with screening and treatment programmes geared towards this high risk group.

FACTORS ASSOCIATED WITH THE LIKELIHOOD OF FURTHER MOVEMENT AMONG MOBILE FEMALE SEX WORKERS IN INDIA: A MULTINOMIAL LOGIT APPROACH

Female sex workers (FSWs) are vulnerable to HIV infection. Their socioeconomic and behavioural vulnerabilities are crucial push factors for movement for sex work. This paper assesses the factors associated with the likelihood of movement of sex workers from their current place of work. Data were derived from a cross-sectional survey conducted among 5498 mobile FSWs in 22 districts of high in-migration across four states in southern India. A multinomial logit model was constructed to predict the likelihood of FSWs moving from their current place of work. Ten per cent of the sampled mobile FSWs were planning to move from their current place of sex work. Educational attainment, marital status, income at current place of work, debt, sexual coercion, experience of violence and having tested for HIV and collected the results were found to be significant predictors of the likelihood of movement from the current place of work. Consistent condom use with different clients was significantly low among those planning to move. Likewise, the likelihood of movement was significantly higher among those who had any STI symptom in the last six months and those who had a high self-perceived risk of HIV. The findings highlight the need to address factors associated with movement among mobile FSWs as part of HIV prevention and access to care interventions.

HIV Incidence and Spatial Clustering in a Rural Area of Southern Mozambique

Background

Monitoring the HIV epidemic in a defined population is critical for planning treatment and preventive strategies. This is especially important in sub-Saharan Africa, which harbours the highest burden of the disease.

Objective

To estimate HIV incidence in adults aged 18-47 years old and to investigate spatial variations of HIV prevalence in Manhiça, a semi-rural area of southern Mozambique.

Methods

Two cross-sectional community-based surveys were conducted in 2010 and 2012 to determine HIV prevalence. Individual participants were randomly selected from the demographic surveillance system in place in the area and voluntary HIV counselling and testing was offered at the household level. HIV incidence was calculated using prevalence estimates from the two sero-surveys. Each participant’s household was geocoded using a global information system. The Spatial Scan Statistics programme was used to identify areas with disproportionate excess in HIV prevalence.

Results

A total of 1511 adults were tested. The estimated HIV prevalence in the community was 39.9% in 2010 and 39.7% in 2012. The overall HIV incidence was 3.6 new infections per 100 person-years at risk (PYAR) [95CI 1.56; 7.88], assuming stable epidemic conditions, and tended to be higher in women (4.9/100 PYAR [95CI 1.74; 11.85]) than in men (3.2/PYAR [95CI 1.36; 9.92]). One cluster with significant excess HIV prevalence was identified at the same geographic location in both surveys. This cluster had an HIV prevalence of 79.0% in 2010 and 52.3% in 2012.

Conclusions

The findings of these first individually-randomised community-HIV sero-surveys conducted in Mozambique reinforce the need to combine HIV incidence estimates and research on micro geographical infection patterns to guide and consolidate effective prevention strategies.

Migrant Workers in Kazakhstan: Gender Differences in HIV Knowledge and Sexual Risk Behaviors

This study compares sexual risk behaviors among male and female migrant market vendors in Almaty, Kazakhstan. From the Barakholka Market, 209 male and 213 female market vendors were randomly recruited. Self-reported data were collected through standardized face-to-face interviews. Dry blood spot was used as specimen for syphilis testing. Propensity score stratification was used to estimate adjusted prevalence or rate ratios by gender. Compared to male migrant workers, females had lower HIV knowledge and were less likely to have multiple sexual partners. There was no evidence of a gender difference for prevalence of syphilis, condom use with unsteady partners, and safe sex communication between couples. Associations between mobility patterns and engagement in multiple sexual partnerships were stronger among women than men. Efforts should be made to mitigate the gender differential in HIV knowledge among migrants, especially women. Such efforts need to be implemented in both home and host countries.

Mathematical Analysis of the Effects of HIV-Malaria Co-infection on Workplace Productivity

In this paper, a nonlinear dynamical system is proposed and qualitatively analyzed to study the dynamics and effects of HIV-malaria co-infection in the workplace. Basic reproduction numbers of sub-models are derived and are shown to have LAS disease-free equilibria when their respective basic reproduction numbers are less than unity. Conditions for existence of endemic equilibria of sub-models are also derived. Unlike the HIV-only model, the malaria-only model is shown to exhibit a backward bifurcation under certain conditions. Conditions for optimal control of the co-infection are derived using the Pontryagin's maximum principle. Numerical experimentation on the resulting optimality system is performed. Using the incremental cost-effectiveness ratio, it is observed that combining preventative measures for both diseases is the best strategy for optimal control of HIV-malaria co-infection at the workplace.

Epidemiology of HIV among US Air Force Military Personnel, 1996-2011

Objective

The objectives of this study were to describe the epidemiology of HIV in the United States Air Force (USAF) from 1996 through 2011 and to assess whether socio-demographic characteristics and service-related mobility, including military deployments, were associated with HIV infection.

Methods

We conducted a retrospective cohort analysis of USAF personnel who were HIV-infected during the study period January 1, 1996 through December 31, 2011 and a matched case-control study. Cases were USAF personnel newly-diagnosed with HIV during the study period. Five randomly-selected HIV-uninfected controls were matched to each case by age, length of service, sex, race, service, component, and HIV test collection date. Socio-demographic and service-related mobility factors and HIV diagnosis were assessed using conditional logistic regression.

Results

During the study period, the USAF had 541 newly diagnosed HIV-infected cases. HIV incidence rate (per 100,000 person-years) among 473 active duty members was highest in 2007 (16.78), among black/ African-American USAF members (26.60) and those aged 25 to 29 years (10.84). In unadjusted analysis restricted to personnel on active duty, 10 characteristics were identified and considered for final multivariate analysis. Of these single (adjusted odds ratio [aOR], 8.15, 95% confidence interval [CI] 5.71–11.6) or other marital status (aOR 4.60, 95% CI 2.72–7.75), communications/ intelligence (aOR 2.57, 95% CI 1.84–3.60) or healthcare (aOR 2.07, 95% CI 1.28–3.35) occupations, and having no deployment in the past 2 years before diagnosis (aOR 2.02, 95% CI 1.47–2.78) conferred higher odds of HIV infection in adjusted analysis.

Conclusion

The highest risk of HIV infection in the USAF was among young unmarried deployment-naïve males, especially those in higher risk occupation groups. In an era when worldwide military operations have increased, these analyses identified potential areas where targeted HIV prevention efforts may be beneficial in reducing HIV incidence in the USAF military population.

HIV prevalence and risk behaviors among Mozambicans working in South African mines

Mineworkers are considered a population at risk for HIV due to risk behaviors associated with migratory work patterns. This was the first study in Mozambique to determine the prevalence of HIV and associated demographic and risk behaviors, and assess use and access to prevention and healthcare services among Mozambicans working in South African mines. Men who had worked in a South African mine in the past 12 months were recruited between February and May 2012 using time location sampling (TLS) at the Ressano Garcia border between Mozambique and South Africa. Demographic and behavioral data were collected through a standardized questionnaire, and HIV prevalence was estimated by testing dried blood spots (DBS) with two enzyme immunoassays. In total, 432 eligible mine workers were recruited. Mean age was 43 years. Most were married or cohabitating; among them, 12.6 % had two or more wives/marital partners in Mozambique. In the 12 months preceding the survey, 24.7 % had an occasional sexual partner, and 6.6 % had at least one partner who was a female sex worker. Only one in five (18.5 %) used a condom during last sex. HIV prevalence among mineworkers was 22.3 %, and 74.6 % of those who tested positive as part of the survey did not know their status. HIV prevalence was significantly higher (p = 0.018) among those that were uncircumcised (31.2 %) than those who were circumcised (18.5 %). Multiple partners (multiple spouses, cross-border relations, and multiple occasional partnerships), inconsistent condom use, and a high proportion of infected mineworkers who do not know their HIV status increases the risk of HIV transmission in this population. Combination strategies involving the promotion of condom use, HIV testing, and male circumcision should be strengthened among mineworkers.

Circular labor migration and HIV in India: exploring heterogeneity in bridge populations connecting areas of high and low HIV infection prevalence

Background. The emerging human immunodeficiency virus (HIV) epidemics in rural areas of India are hypothesized to be linked to circular migrants who are introducing HIV from destination areas were the prevalence of HIV infection is higher. We explore the heterogeneity in potential roles of circular migrants in driving an HIV epidemic in a rural area in north India and examine the characteristics of the “sustaining bridge population”, which comprises individuals at risk of HIV acquisition at destination and of HIV transmission into networks at origin capable of sustaining an epidemic.

Methods. Results of a behavioral survey of 639 male migrants from Azamgarh district, India, were analyzed using χ² tests and logistic regression.

Results. We estimated the size of various subgroups defined by specific sexual behaviors across different locations and over time. Only 20% fit our definition of a sustaining bridge population, with the majority making no apparent contribution to geographical connectedness between high- and low-prevalence areas. However, we found evidence of sexual contacts at origin that could potentially sustain an epidemic once HIV is introduced. Variables associated with sustaining bridge population membership were self-perceived HIV risk, current migrant status, and age.

Conclusions. Circular migrants represent a heterogeneous population in terms of their role as a bridge group. Self-perception of heightened risk could be exploited in designing prevention programs.