Place matters: multilevel investigation of HIV distribution in Tanzania

Spatial distribution and determinants of HIV prevalence among adults in urban Ethiopia: Findings from the Ethiopia Population-based HIV Impact Assessment Survey (2017–2018)

The design and evaluation of national HIV programs often rely on aggregated national data, which may obscure localized HIV epidemics. In Ethiopia, even though the national adult HIV prevalence has decreased, little information is available about local areas and subpopulations. To inform HIV prevention efforts for specific populations, we identified geographic locations and drivers of HIV transmission. We used data from adults aged 15–64 years who participated in the Ethiopian Population-based HIV Impact Assessment survey (October 2017–April 2018). Location-related information for the survey clusters was obtained from the 2007 Ethiopia population census. Spatial autocorrelation of HIV prevalence data were analyzed via a Global Moran’s I test. Geographically weighted regression analysis was used to show the relationship of covariates. The finding indicated that uncircumcised men in certain hotspot towns and divorced or widowed individuals in hotspot woredas/towns might have contributed to the average increase in HIV prevalence in the hotspot areas. Hotspot analysis findings indicated that, localized, context-specific intervention efforts tailored to at-risk populations, such as divorced or widowed women or uncircumcised men, could decrease HIV transmission and prevalence in urban Ethiopia.

Sexual and Gender-Based Violence and Vulnerability to HIV Infection in Uganda: Evidence from Multilevel Modelling of Population-Level HIV/AIDS Data

Background: Sexual and gender-based violence (SGBV) is highly prevalent in Uganda and its link with HIV infection and compromising access to HIV/AIDS services is known. However, current evidence is controversial. Most of the studies indicate a positive relationship but a few indicate otherwise. Moreover, there is no research examining the effects of community-level SGBV on HIV infection. Objectives: This research explores the association between SGBV and vulnerability to HIV infection. Methods: Multilevel binary logistic regression is applied to secondary data of Uganda AIDS Indicators Survey conducted in 2011. The survey data comprises 12,153 women and 9588 men. Results: SGBV significantly increases the likelihood of HIV infection, with victims having 34%, 1.34 [1.06–1.70] higher odds than non-victims. At the community level, wealth, and pre-sex alcohol abuse are important determinants. Conclusions: Vulnerability to the risk of HIV infection in Uganda is associated with individual-level and community factors. Effective HIV prevention policies need to pay attention to victims of SGBV using individual- and community-level strategies.

A decade of sustained geographic spread of HIV infections among women in Durban, South Africa

Background

Fine scale geospatial analysis of HIV infection patterns can be used to facilitate geographically targeted interventions. Our objective was to use the geospatial technology to map age and time standardized HIV incidence rates over a period of 10 years to identify communities at high risk of HIV in the greater Durban area.

Methods

HIV incidence rates from 7557 South African women enrolled in five community-based HIV prevention trials (2002–2012) were mapped using participant household global positioning system (GPS) coordinates. Age and period standardized HIV incidence rates were calculated for 43 recruitment clusters across greater Durban. Bayesian conditional autoregressive areal spatial regression (CAR) was used to identify significant patterns and clustering of new HIV infections in recruitment communities.

Results

The total person-time in the cohort was 9093.93 years and 613 seroconversions were observed. The overall crude HIV incidence rate across all communities was 6·74 per 100PY (95% CI: 6·22–7·30). 95% of the clusters had HIV incidence rates greater than 3 per 100PY. The CAR analysis identified six communities with significantly high HIV incidence. Estimated relative risks for these clusters ranged from 1.34 to 1.70. Consistent with these results, age standardized HIV incidence rates were also highest in these clusters and estimated to be 10 or more per 100 PY.

Compared to women 35+ years old younger women were more likely to reside in the highest incidence areas (aOR: 1·51, 95% CI: 1·06–2·15; aOR: 1.59, 95% CI: 1·19–2·14 and aOR: 1·62, 95% CI: 1·2–2·18 for < 20, 20–24, 25–29 years old respectively). Partnership factors (2+ sex partners and being unmarried/not cohabiting) were also more common in the highest incidence clusters (aOR 1.48, 95% CI: 1.25–1.75 and aOR 1.54, 95% CI: 1.28–1.84 respectively).

Conclusion

Fine geospatial analysis showed a continuous, unrelenting, hyper HIV epidemic in most of the greater Durban region with six communities characterised by particularly high levels of HIV incidence. The results motivate for comprehensive community-based HIV prevention approaches including expanded access to PrEP. In addition, a higher concentration of HIV related services is required in the highest risk communities to effectively reach the most vulnerable populations.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4080-6) contains supplementary material, which is available to authorized users.

Using multilevel models to evaluate the influence of contextual factors on HIV/AIDS, sexually transmitted infections, and risky sexual behavior in sub-Saharan Africa: a systematic review

PURPOSE

To describe the use of multilevel models (MLMs) in evaluating the influence of contextual factors on HIV/AIDS, sexually transmitted infections (STIs), and risky sexual behavior (RSB) in sub-Saharan Africa.

METHODS

Ten databases were searched through May 29, 2016. Two reviewers completed screening and full-text review. Studies examining the influence of contextual factors on HIV/AIDS, STIs, and RSB and using MLMs for analysis were included. The Quality Assessment Tool for Quantitative Studies was used to evaluate study quality.

RESULTS

A total of 118 studies met inclusion criteria. Seventy-four studies focused on HIV/AIDS-related topics; 46 focused on RSB. No studies related to STIs other than HIV/AIDS met the eligibility criteria. Of five studies examining HIV serostatus and community socioeconomic factors, three found an association between poverty and measures of inequality and increased HIV prevalence. Among studies examining RSB, associations were found with numerous contextual factors, including poverty, education, and gender norms.

CONCLUSIONS

Studies using MLMs indicate that several contextual factors, including community measures of socioeconomic status and educational attainment, are associated with a number of outcomes related to HIV/AIDS and RSB. Future studies using MLMs should focus on contextual-level interventions to strengthen the evidence base for causality.

Prevalence of Lymphatic Filariasis and Treatment Effectiveness of Albendazole/ Ivermectin in Individuals with HIV Co-infection in Southwest-Tanzania

BACKGROUND

Annual mass treatment with ivermectin and albendazole is used to treat lymphatic filariasis in many African countries, including Tanzania. In areas where both diseases occur, it is unclear whether HIV co-infection reduces treatment success.

METHODOLOGY

In a general population study in Southwest Tanzania, individuals were tested for HIV and circulating filarial antigen, an indicator of Wuchereria bancrofti adult worm burden, before the first and after 2 consecutive rounds of anti-filarial mass drug administration.

PRINCIPLE FINDINGS

Testing of 2104 individuals aged 0-94 years before anti-filarial treatment revealed a prevalence of 24.8% for lymphatic filariasis and an HIV-prevalence of 8.9%. Lymphatic filariasis was rare in children, but prevalence increased in individuals above 10 years, whereas a strong increase in HIV was only seen above 18 years of age. The prevalence of lymphatic filariasis in adults above 18 years was 42.6% and 41.7% (p = 0.834) in HIV-negatives and-positives, respectively. Similarly, the HIV prevalence in the lymphatic filariasis infected (16.6%) and uninfected adult population (17.1%) was nearly the same. Of the above 2104 individuals 798 were re-tested after 2 rounds of antifilarial treatment. A significant reduction in the prevalence of circulating filarial antigen from 21.6% to 19.7% was found after treatment (relative drop of 8.8%, McNemar's exact p = 0.036). Furthermore, the post-treatment reduction of CFA positivity was (non-significantly) larger in HIV-positives than in HIV-negatives (univariable linear regression p = 0.154).

CONCLUSION/SIGNIFICANCE

In an area with a high prevalence for both diseases, no difference was found between HIV-infected and uninfected individuals regarding the initial prevalence of lymphatic filariasis. A moderate but significant reduction in lymphatic filariasis prevalence and worm burden was demonstrated after two rounds of treatment with albendazole and ivermectin. Treatment effects were more pronounced in the HIV co-infected subgroup, indicating that the effectiveness of antifilarial treatment was not reduced by concomitant HIV-infection. Studies with longer follow-up time could validate the observed differences in treatment effectiveness.

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.

The AIDS epidemic in the Amazon region: a spatial case-control study in Rondonia, Brazil

OBJECTIVE

To analyze spatial changes in the risk of AIDS and the relationship between AIDS incidence and socioeconomic variables in the state of Rondonia, Amazon region.

METHODS

A spatial, population case-control study in Rondonia, Brazil, based on 1,780 cases reported to the Epidemiological Surveillance System and controls based on demographic data from 1987 to 2006. The cases were grouped into five consecutive four-year periods. A generalized additive model was adjusted to the data; the dependent variable was the status of the individuals (case or control), and the independent variables were a bi-dimensional spline of the geographic coordinates and some municipality-level socioeconomic variables. The observed values of the Moran's I test were compared to a reference distribution of values generated under conditions of spatial randomness.

RESULTS

AIDS risk shows a marked spatial and temporal pattern. The disease incidence is related to socioeconomic variables at the municipal level in Rondônia, such as urbanization and human capital. The highest incidence rates of AIDS are in municipalities along the BR-364 highway and calculations of the Moran's I test show positive spatial correlation associated with proximity of the municipality to the highway in the third and fourth periods (p = 0.05).

CONCLUSIONS

Incidence of the disease is higher in municipalities of greater economic wealth and urbanization, and in those municipalities bisected by Rondônia's main roads. The rapid development associated with the opening up of once remote regions may be accompanied by an increase in these risks to health.

Community-level income inequality and HIV prevalence among persons who inject drugs in Thai Nguyen, Vietnam

Socioeconomic status has a robust positive relationship with several health outcomes at the individual and population levels, but in the case of HIV prevalence, income inequality may be a better predictor than absolute level of income. Most studies showing a relationship between income inequality and HIV have used entire countries as the unit of analysis. In this study, we examine the association between income inequality at the community level and HIV prevalence in a sample of persons who inject drugs (PWID) in a concentrated epidemic setting. We recruited PWID and non-PWID community participants in Thai Nguyen, Vietnam, and administered a cross-sectional questionnaire; PWID were tested for HIV. We used ecologic regression to model HIV burden in our PWID study population on GINI indices of inequality calculated from total reported incomes of non-PWID community members in each commune. We also modeled HIV burden on interaction terms between GINI index and median commune income, and finally used a multi-level model to control for community level inequality and individual level income. HIV burden among PWID was significantly correlated with the commune GINI coefficient (r = 0.53, p = 0.002). HIV burden was also associated with GINI coefficient (β = 0.082, p = 0.008) and with median commune income (β = −0.018, p = 0.023) in ecological regression. In the multi-level model, higher GINI coefficient at the community level was associated with higher odds of individual HIV infection in PWID (OR = 1.46 per 0.01, p = 0.003) while higher personal income was associated with reduced odds of infection (OR = 0.98 per $10, p = 0.022). This study demonstrates a context where income inequality is associated with HIV prevalence at the community level in a concentrated epidemic. It further suggests that community level socioeconomic factors, both contextual and compositional, could be indirect determinants of HIV infection in PWID.

Estimating the size of the female sex worker population in Kenya to inform HIV prevention programming

Background

The high burden of HIV infections among female sex workers (FSW) in sub-Saharan Africa has been long recognised, but effective preventive interventions have largely not been taken to scale. We undertook a national geographical mapping exercise in 2011/2012 to assess the locations and population size of FSW in Kenya, to facilitate targeted HIV prevention services for this population.

Methods and Findings

We used a geographical mapping approach, consisting of interviews with secondary key informants to identify “hot” spots frequented by FSW, their operational dynamics and the estimated numbers of FSW in those spots. This was followed by validation of the estimates through interviews with FSW at each spot identified. The mapping covered Nairobi, the capital city of Kenya, and 50 other major urban centres. In total, 11,609 secondary key informant interviews were conducted to identify FSW spots. Further, a total of 6,360 FSW were interviewed for spot validation purposes. A total of 10,670 spots where FSW congregate were identified. The estimated FSW population in all the towns mapped was 103,298 (range 77,878 to 128, 717). Size estimates in the towns mapped were extended to smaller towns that were not mapped, using a statistical model. The national urban FSW population estimate was 138,420 (range 107, 552 to 169, 288), covering all towns of over 5,000 population. We estimated that approximately 5% of the urban female population of reproductive age in Kenya could be sex workers, which is consistent with previous estimates from other sub-Saharan African countries.

Conclusions

This study provides the first national level data on the size of the FSW population in Kenya. These data can be used to enhance HIV prevention programme planning and implementation for FSW, to form the basis for impact evaluations, and to improve programme coverage by directing efforts to locations with the greatest need.

HIV prevalence and risk in long-distance truck drivers in South Africa: a national cross-sectional survey

We estimated the prevalence of HIV and assessed correlates of HIV infection in long-distance truck drivers in South Africa. Between October 2003 and July 2004, 1900 long-distance truck drivers aged ≥18 years consented to interview and for testing for HIV. Participants were selected from a 10% stratified random sample of registered truck depots. A proximate-determinants framework was used to assess the hierarchical relationship between risk factors and HIV infection using logistic regression. HIV prevalence was 26% (95% confidence interval 24% to 28%). In multivariate analyses, HIV infection was associated with spending 2–4 weeks on the road (adjusted odds ratio 1.4; 95% confidence interval 1.1 to 1.9). There was modest evidence of a dose-response relationship between time on the road and HIV risk. Mobility increased risk by creating conditions for unsafe sex and reducing access to health services. Targeted HIV interventions for long-distance truck drivers are needed.

HIV, poverty and women

This review examines the interactions of financial status and HIV and its implications for women. MEDLINE and Google scholar were searched using the keywords 'women', 'poverty' and 'HIV' in any field of the article. The search was limited to articles published in English over the last 10 years. The first section of the article tries to establish whether poverty or wealth is a risk factor for HIV. There is credible evidence for both arguments. While wealth shows an increased risk for both sexes, poverty places women at a special disadvantage. The second section explains how the financial status interacts with other 'non biological' factors to put women at increased risk. While discrimination based on these factors disadvantage women, there are some paradoxical observations that do not fit with the traditional line of explanation (e.g. paradoxical impact of wealth and education on HIV). The final section assesses the impact of HIV in driving poverty and the role of women in interventional programmes. The specific impact of poverty on females in families living with HIV is less explored. Though microfinance initiatives to empower women are a good idea in theory, the actual outcome of such a programme is less convincing.

Community influences on married men's uptake of HIV testing in eight African countries

Despite efforts to increase HIV testing in the African region, the proportion of men who report ever having been tested for HIV remains low. Research has focused on individual level determinants of women's testing however little is known about factors associated with men's testing behavior. This analysis investigates community influences on HIV testing among men ages 15-54, using Demographic and Health Survey (DHS) data from Chad, Ghana, Malawi, Nigeria, Tanzania, Uganda, Zambia, and Zimbabwe. Multilevel models were fitted in each country for the outcome of ever receiving an HIV test. After controlling for individual and household level factors, community level factors of demographics, economics, and behavior and knowledge remain significantly associated with HIV testing among men. The results of this analysis highlight the need to recognize the impact of community influences on men's HIV test seeking behavior, and to harness these community factors in the design of programs aimed at encouraging the uptake of HIV testing among men in Africa.

A multilevel analysis of the impact of socio-structural and environmental influences on condom use among female sex workers

This study uses multilevel analysis to examine individual, organizational and community levels of influence on condom use among female commercial sex workers (FSW) in the Philippines. A randomized controlled study involving 1,382 female commercial sex workers assigned to three intervention groups consisting of peer education, managerial training, combined peer and managerial intervention and a usual care control group was conducted. The results of the multilevel analysis show that FSWs who work in establishments with condom use rules tend to have a higher level of condom use (β = .70, P < 0.01). Among the different intervention groups, the combined peer and managerial intervention had the largest effect on condom use (β = 1.30, P < 0.01) compared with the usual care group. Using a three-level hierarchical model, we found that 62% of the variation lies within individuals, whereas 24% and 14% of the variation lies between establishments, and communities, respectively. Standard errors were underestimated when clustering of the FSWs in the different establishments and communities were not taken into consideration. The results demonstrate the importance of using multilevel analysis for community-based HIV/AIDS intervention programs to examine individual, establishment and community effects.

THE HIV–POVERTY THESIS RE-EXAMINED: POVERTY, WEALTH OR INEQUALITY AS A SOCIAL DETERMINANT OF HIV INFECTION IN SUB-SAHARAN AFRICA?

Although health is generally believed to improve with higher wealth, research on HIV in sub-Saharan Africa has shown otherwise. Whereas researchers and advocates have frequently advanced poverty as a social determinant that can help to explain sub-Saharan Africa's disproportionate burden of HIV infection, recent evidence from population surveys suggests that HIV infection is higher among wealthier individuals. Furthermore, wealthier countries in Africa have experienced the fastest growing epidemics. Some researchers have theorized that inequality in wealth may be more important than absolute wealth in explaining why some countries have higher rates of infection and rapidly increasing epidemics. Studies taking a longitudinal approach have further suggested a dynamic process whereby wealth initially increases risk for HIV acquisition and later becomes protective. Prior studies, conducted exclusively at either the individual or the country level, have neither attempted to disentangle the effects of absolute and relative wealth on HIV infection nor to look simultaneously at different levels of analysis within countries at different stages in their epidemics. The current study used micro-, meso- and macro-level data from Demographic and Health Surveys (DHS) across 170 regions within sixteen countries in sub-Saharan Africa to test the hypothesis that socioeconomic inequality, adjusted for absolute wealth, is associated with greater risk of HIV infection. These analyses reveal that inequality trumps wealth: living in a region with greater inequality in wealth was significantly associated with increased individual risk of HIV infection, net of absolute wealth. The findings also reveal a paradox that supports a dynamic interpretation of epidemic trends: in wealthier regions/countries, individuals with less wealth were more likely to be infected with HIV, whereas in poorer regions/countries, individuals with more wealth were more likely to be infected with HIV. These findings add additional nuance to existing literature on the relationship between HIV and socioeconomic status.

Space-time confounding adjusted determinants of child HIV/TB mortality for large zero-inflated data in rural South Africa

South Africa is experiencing a major burden of HIV/TB. We used longitudinal data from the Agincourt sub-district in rural northeast South Africa over the years 2000 to 2005. A total of 187 HIV/TB deaths were observed among 16,844 children aged 1-5 years coming from 8,863 households. In this paper we used Bayesian models to assess risk factors for child HIV/TB mortality taking into account the presence of spatial correlation. Bayesian zero inflated spatiotemporal models were able to detect hidden patterns within the data. Our main finding was that maternal orphans experienced a threefold greater risk of HIV/TB death compared to those with living mothers (AHR=2.93, 95% CI[1.29;6.93]). Risk factor analyses which adjust for person, place and time provide evidence for policy makers that includes a spatial distribution of risk. Child survival is dependent on the mother's survival; hence programs that promote maternal survival are critical.

Using matched areas to explore international differences in population health

In this paper, we develop and test a method for examining the influence of national level contextual influences on population health. Acknowledging calls for the use of experimental study designs to explore contextual influences on health, we develop a study design in which sets of local areas from Britain and Belgium became akin to two 'treatment' groups; one exposed to British society and culture and the other exposed to Belgian society and culture. The areas are matched on the basis of showing very strong similarities in economic, demographic and historical characteristics. Data describing these characteristics are obtained from national census data. A principal component analysis of these variables permits areas in Britain and Belgium with similar scores on the resulting components to be matched into pairs. A sequence of logistic regression models identifies between-country difference in the risk of reporting poor health. Our final model compares the risk of reporting poor health among Belgians and people from Britain living in similar local contexts, adjusting for any residual differences in individual level characteristics. We compare results from this new method with those from more conventional approaches. All approaches show that residence in Britain is associated with a substantial and significantly higher risk of reporting poor health for both men and women, after adjustment for both individual and local contextual influences. We then critically reflect on our method and on the context-composition framework for research into area variation in health. We conclude that whilst our approach succeeded in applying the idea of comparable groups with different exposures to an observational, international comparison, it also brought associated questions about external validity and the extent to which a sample of matched areas captures a 'national' context.

It's not just who you are but where you live: an exploration of community influences on individual HIV status in rural Malawi

Approximately 1 million people are infected with Human Immunodeficiency Virus (HIV) in Malawi. Despite efforts aimed at changing individual risk behaviors, HIV prevalence continues to rise among rural populations. Both previous research and the Political Economy of Health framework suggest that community-based socio-economic factors and accessibility may influence HIV transmission; however, these community factors have received little empirical investigation. To fill this gap, this research uses data from a nationally representative probability sample of rural Malawians combined with small area estimates of community socio-economic and accessibility data in logistic regression models to: 1) reveal relationships between community factors and individual HIV status; 2) determine whether these relationships operate through individual HIV risk behaviors; and 3) explore whether these associations vary by gender. Community socio-economic factors include relative and absolute poverty; community accessibility factors include distance to roads, cities, and public health facilities. Individual HIV risk behaviors include reported condom use, sexually transmitted infections, multiple partnerships, and paid sex. Results show that higher community income inequality, community proximity to a major road, and community proximity to a public health clinic are associated with increased odds of HIV for women. For men, community proximity to a major road and community proximity to a public health clinic are associated with increased odds of HIV infection. These direct relationships between community factors and individual HIV status are not mediated by individual HIV risk behaviors. The Political Economy of Health frames the discussion. This study provides evidence for expanding HIV prevention efforts beyond individual risk behaviors to consideration of community factors that may drive the HIV epidemic in rural Malawi.

HIV-malaria co-infection: effects of malaria on the prevalence of HIV in East sub-Saharan Africa

OBJECTIVE

To examine the association between malaria and HIV prevalence in East sub-Saharan Africa.

METHODS

Using large nationally representative samples of 19,735 sexually active adults from the 2003-04 HIV/AIDS indicator surveys conducted in Kenya, Malawi and Tanzania, and the atlas malaria project, we analysed the relationship between malaria and HIV prevalence adjusting for important socioeconomic and biological cofactors.

RESULTS

In adjusted models, individuals who live in areas with high Plasmodium falciparum parasite rate (PfPR > 0.42) had increased estimated odds of being HIV positive than individuals who live in areas with low P. falciparum parasite rate (PfPR ≤ 0.10) [men: estimated odds ratio (OR) 2.24, 95% confidence interval (CI) 1.62-3.12; women: estimated OR 2.44, 95% CI 1.85-3.21].

CONCLUSION

This is the first study to report malaria as a risk factor of concurrent HIV infection at the population level. According to our results, individuals who live in areas with high P. falciparum parasite rate have about twice the risk of being HIV positive compared with individuals who live in areas with low P. falciparum parasite rate. Our work emphasizes the need for field studies focused on quantifying the interaction among parasitic infections and risk of HIV infection, and studies to explore the impact of control interventions. Programmes focused on reducing malaria transmission will be important to address, especially in HIV-infected individuals.

Social venues that protect against and promote HIV risk for young men in Dar es Salaam, Tanzania

Developing effective place-based health interventions requires understanding of the dynamic between place and health. The therapeutic landscape framework explains how place-based social processes and physical geography interact and influence health behavior. This study applied this framework to examine how venues, or social gathering places, influenced HIV risk behavior among young, urban men in Tanzania. Eighty-three public venues where men aged 15-19 met new sexual partners were identified by community informants in one city ward. The majority (86%) of the venues were called 'camps', social gathering places that had formal leaders and members. Observations were conducted at 23 camps and in-depth interviews were conducted with 36 camp members and 10 camp leaders in 15 purposively selected camps. Geographic and social features of camps were examined to understand their contributions to men's behaviors. Camps were characterized by a geographic space claimed by members, a unique name and a democratic system of leadership and governance. Members were mostly men and socialized daily at their camp. They reported strong social bonds and engaging in health-promoting activities such as playing sports and generating income. Members also engaged in HIV risk behaviors, such as meeting new sexual partners and having sex in or around the camp at night. Some members promoted concurrent sexual partnerships with their friends and resisted camp leaders' efforts to change their sexual risk behavior. We conclude that camps are strategic venues for HIV prevention programs for young Tanzanian men. They served as both protective and risk landscapes, illustrating three domains of the therapeutic landscape framework: the built environment; identities of landscape occupants; and sites for collective efficacy. The framework and data suggest HIV intervention components might augment the protective features of the camps, while changing environmental features to reduce risk.

The social determinants of HIV serostatus in sub-Saharan Africa: an inverse relationship between poverty and HIV?

Contrary to theories that poverty acts as an underlying driver of human immunodeficiency virus (HIV) infection in sub-Saharan Africa (SSA), an increasing body of evidence at the national and individual levels indicates that wealthier countries, and wealthier individuals within countries, are at heightened risk for HIV. This article reviews the literature on what has increasingly become known as the positive-wealth gradient in HIV infection in SSA, or the counterintuitive finding that the poor do not have higher rates of HIV. This article also discusses the programmatic and theoretical implications of the positive HIV-wealth gradient for traditional behavioral interventions and the social determinants of health literature, and concludes by proposing that economic and social policies be leveraged as structural interventions to prevent HIV in SSA.

Assessing the role of individual and neighbourhood characteristics in HIV testing: evidence from a population based survey

OBJECTIVES

Individuals living in deprived neighbourhoods have poor health outcomes, including human immunodeficiency virus (HIV) infection mortality. We assessed the association between individual and neighbourhood characteristics, and HIV testing across Canada.

METHODS

We used logistic regression modelling to evaluate this association in 2219 men and 2815 women, aged 18-54 years, in Canada, using data from the National Population Health Survey (1996/7),. Socio-economic characteristics and presence of a sexually transmitted infection (STI) were the individual level characteristics. Small area of residence was classified according to categories of material and social deprivation; these were the 'neighbourhood' variables in the model.

RESULTS

Ethnic minority women were less likely to report an HIV test than white women (OR 0.44, 95% CI: 0.23 to 0.86). Women without a regular doctor were significantly less likely to report ever having had an HIV test (OR 0.57, 95% CI: 0.35 to 0.93). Adjusting for individual level characteristics, we found that men and women living in the most materially deprived neighbourhoods were slightly less likely to report HIV testing than those living in the least deprived neighbourhoods (Men - OR 0.61, 95% CI: 0.34 to 1.08; Women - OR 0.62, 95% CI: 0.38 to 1.00).

DISCUSSION

Thus, living in poor neighbourhoods was associated with poor uptake of an HIV test. These economic disparities should be taken in account while designing future prevention strategies. Ethnic minority women were less likely to go for HIV testing and culturally appropriate messages may be required for prevention in ethnic minorities.

Rethinking the role of the local community in HIV epidemic spread in sub-Saharan Africa: a proximate-determinants approach

The spread of HIV in sub-Saharan Africa continues largely unabated. To improve prevention interventions, a better understanding of the determinants of HIV infection is required. Conceptual frameworks can guide epidemiological investigation and prevent a misguided focus on single risk factors in isolation. Existing frameworks of HIV infection focus on transmission. However, the transmitting individual is rarely known. By contrast, data on individual HIV acquisition are available from longitudinal studies and tests for recent HIV infection. From the perspective of individuals susceptible to HIV, it is important to distinguish between factors determining the individual's biological disposition and sexual behavior and community-level factors, which can affect both HIV acquisition and the likelihood that a sex partner chosen from a community will be infected with HIV and transmit the infection. We propose a framework that takes the susceptible individual as a starting point and links distal, proximate and biological determinants of HIV infection at both the individual and the community level. We describe three necessary ingredients for the use of the framework (identification of the relevant community, multilevel analysis and methods for causal inference).

Willingness to volunteer in a Phase I/II HIV vaccine trial: a study among police officers in Dar es Salaam, Tanzania

Background

As HIV infection continues to devastate low-income countries, efforts to search for an effective HIV vaccine are crucial. Therefore, participation in HIV vaccine trials will be useful for the development of a preventive vaccine that will work and thus reduce the global HIV epidemic.

Objective

The objective of this study was to analyse the willingness to volunteer (WTV) in a Phase I/II HIV vaccine trial among police officers in Dar es Salaam, Tanzania.

Design

We included a convenience sample of 329 participants (79% males) from sensitisation workshops that were held once at each of the 32 police stations. Participants were recruited from 23 stations which were included according to availability. Data about personal characteristics, general HIV and AIDS knowledge and sexual behaviour, attitudes towards vaccines and willingness to participate in the HIV vaccine trial were obtained through an interview-administered questionnaire with both closed and open-ended questions.

Results

Overall, 61% of the participants expressed WTV in HIV vaccine trials. WTV was significantly associated with: positive attitude towards use of effective vaccine, Odds ratio (OR), 36.48 (95% CI: 15.07–88.28); the intention to tell others about one's decision to participate in the trial, OR, 6.61 (95% CI: 3.89–11.24); Tanzania becoming a partner in developing the vaccine, OR, 4.28 (95% CI: 2.28–8.03); having an extra sexual partner, OR, 3.05 (95% CI: 1.63–5.69); perceived higher risk of getting HIV infection, OR, 2.11 (95% CI: 1.34–3.33); and high knowledge about HIV and AIDS, OR, 1.92 (95% CI: 1.22–3.01).

Conclusion

The results indicated that a majority of police officers in this study were willing to participate in HIV vaccine trials. However, there is a need to provide the respondents with precise information about the purpose of a Phase I/II HIV vaccine trial and the fact that it does not protect against HIV infection, in order to avoid increasing risky behaviour.

Associations between social capital and HIV stigma in Chennai, India: considerations for prevention intervention design

Stigma against persons living with HIV/AIDS (PLHA) is a barrier to seeking prevention education, HIV testing, and care. Social capital has been reported as an important factor influencing HIV prevention and social support upon infection. In the study, we explored the associations between social capital and stigma among men and women who are patrons of wine shops or community-based alcohol outlets in Chennai. We found that reports of social capital indicators were associated with reduced fear of transmission of HIV/AIDS, lower levels of feelings of shame, blame and judgment, lower levels of personal support and perceived community support for discriminatory actions against PLHA. Specifically, when participants reported membership in formal groups, perception of high levels of collective action toward community goals, high norms of reciprocity between neighbors and residents in daily life, and presence of trusted sexually transmitted disease care providers, all levels of measures of stigma were lower. Although we defined social capital rather narrowly in this study, our findings suggest that seeking partnerships with existing organizations and involving health care providers in future interventions may be explored as a strategy in community-based prevention interventions.

Localized spatial clustering of HIV infections in a widely disseminated rural South African epidemic

BACKGROUND

South Africa contains more than one in seven of the world's HIV-positive population. Knowledge of local variation in levels of HIV infection is important for prioritization of areas for intervention. We apply two spatial analytical techniques to investigate the micro-geographical patterns and clustering of HIV infections in a high prevalence, rural population in KwaZulu-Natal, South Africa.

METHODS

All 12,221 participants who consented to an HIV test in a population under continuous demographical surveillance were linked to their homesteads and geo-located in a geographical information system (accuracy of <2 m). We then used a two-dimensional Gaussian kernel of radius 3 km to produce robust estimates of HIV prevalence that vary across continuous geographical space. We also applied a Kulldorff spatial scan statistic (Bernoulli model) to formally identify clusters of infections (P < 0.05).

RESULTS

The results reveal considerable geographical variation in local HIV prevalence (range = 6-36%) within this relatively homogenous population and provide clear empirical evidence for the localized clustering of HIV infections. Three high-risk, overlapping spatial clusters [Relative Risk (RR) = 1.34-1.62] were identified by the Kulldorff statistic along the National Road (P < or = 0.01), whereas three low risk clusters (RR = 0.2-0.38) were identified elsewhere in the study area (P < or = 0.017).

CONCLUSIONS

The findings show the existence of several localized HIV epidemics of varying intensity that are partly contained within geographically defined communities. Despite the overall high prevalence of HIV in many rural South African settings, the results support the need for interventions that target socio-geographic spaces (communities) at greatest risk to supplement measures aimed at the general population.