Estimates of the size of key populations at risk for HIV infection: men who have sex with men, female sex workers and injecting drug users in Nairobi, Kenya

Programmatic mapping and estimating the population size of female sex workers, men who have sex with men, people who inject drugs and transgender populations in Kenya

Introduction

Effective coverage of Human Immunodeficiency Virus prevention services for Key Populations (KPs) including female sex workers (FSWs), men who have sex with men (MSM), people who inject drugs (PWID) and transgender (TG) people necessitates periodic validation of physical venues and size estimates. Kenya conducted a robust size estimation of KPs in 2012 and a repeat mapping and size estimation exercise was conducted in 2018 to update KP Size Estimates and sub-typologies within each County for calculation of realistic program indicators.

Methods

A prospective mixed methods programmatic mapping approach adopted comprised two steps. The first step involved consolidating and documenting all known venues where KPs congregate while the second step included visiting and validating these venues confirming their active status. Data were collected in 34 out of 47 Counties in Kenya between January and March 2018. Data collected included estimated number of KPs (range), venue typology and timing of operation of each venue.

Results

We estimated a total number of 167,940 (129,271 to 206,609) FSWs; 32,580 (24,704 to 40,455) MSM; 16,063 (12,426 to 19,691) PWIDs and 4,305 (2,826 to 5,783) transgender people congregating at 10,250, 1,729, 401 and 1,218 venues respectively. Majority of the venues for FSW (81%), MSM (64%) and transgender people (67%) were bars with and without lodging, PWIDs were mostly found on streets and injecting dens (70%). Around 9% of FSW and MSM and11% of PWIDs were below the age of 18 years.

Conclusion

This study provided information on young KPs, female PWIDs, MSWs and for the first time, TG people in Kenya. The exercise updated size estimates of KPs by typology and provided new evidence for resource allocation, planning of interventions and targets. Programmatic mapping continues to be a useful approach supporting programs to achieve high levels of coverage and prioritize resources.

Dyspareunia, signs of epithelial disruption, sexual abstinence, and HIV status in female sex workers in Nairobi: a cross-sectional study

BACKGROUND

Epithelial trauma is a risk factor of HIV infection in men who have sex with men (MSM) and female sex workers (FSWs). Painful intercourse may be indicative of epithelial tissue disruption. Previous studies on a cohort of Kenyan FSWs established an association between prolonged sexual abstinence and late HIV seroconversion. Our research objective was to establish whether there is a relationship between HIV serostatus and signs of epithelial disruption and between HIV serostatus and sexual abstinence behaviour.

METHODS

Participants were selected from a Nairobi health facility. A structured questionnaire was administered to 322 FSWs, who provided data on HIV status, sexual behaviour, abstinence intervals and the level of sexual dysfunction. Sexual dysfunction scores were created using parts of the Female Sexual Function Index (FSFI-19). Additional questions addressed epithelial trauma signs. Descriptive data analysis, bivariate and multivariate logistic regression were used to describe the study population and determine factors associated with living with HIV. Potential factors influencing sexual dysfunction were assessed by FSWs via self-rating.

RESULTS

36% of FSWs reported discomfort or pain during vaginal penetration half the time. 44% noticed genital bleeding half the time. Vaginal tenderness was experienced by 70.6% half the time during or after intercourse. Variables predictive of living with HIV on multivariate analysis included a medium and high score of discomfort or pain during and following vaginal penetration (medium: AOR 2.288, p-value 0.032, 95% CI 1.075-4.871; high: AOR 3.044, p-value 0.031, 95% CI 1.110-8.348). No significant association of HIV status with past abstinence durations as reported by participants could be established in the multivariate analysis. A majority of FSWs agreed that steady partnerships (81% agreement), regularity of intercourse (74%), foreplay (72%) and lubricants (65%) alleviated dyspareunia.

CONCLUSIONS

Recurrent exposure to blood during sex was highly prevalent in FSWs, as was sexual dysfunction. Complaint levels were associated with living with HIV, providing evidence that reducing sexual dysfunctions may prevent HIV transmission. Preventive initiatives may be created that address sexual dysfunction in key populations and general populations with a high HIV prevalence. Subjective assessments indicate that prevention may include the promotion of sexual intercourse regularity, foreplay, and lubricant use.

Hidden population size estimation and diagnostics using two respondent-driven samples with applications in Armenia

Estimating the size of hidden populations is essential to understand the magnitude of social and healthcare needs, risk behaviors, and disease burden. However, due to the hidden nature of these populations, they are difficult to survey, and there are no gold standard size estimation methods. Many different methods and variations exist, and diagnostic tools are needed to help researchers assess method-specific assumptions as well as compare between methods. Further, because many necessary mathematical assumptions are unrealistic for real survey implementation, assessment of how robust methods are to deviations from the stated assumptions is essential. We describe diagnostics and assess the performance of a new population size estimation method, capture-recapture with successive sampling population size estimation (CR-SS-PSE), which we apply to data from 3 years of studies from three cities and three hidden populations in Armenia. CR-SS-PSE relies on data from two sequential respondent-driven sampling surveys and extends the successive sampling population size estimation (SS-PSE) framework by using the number of individuals in the overlap between the two surveys and a model for the successive sampling process to estimate population size. We demonstrate that CR-SS-PSE is more robust to violations of successive sampling assumptions than SS-PSE. Further, we compare the CR-SS-PSE estimates to population size estimations using other common methods, including unique object and service multipliers, wisdom of the crowd, and two-source capture-recapture to illustrate volatility across estimation methods.

Evaluation of factors associated with HIV self-testing Acceptability and Uptake among the MSM community in Nairobi, Kenya: A cross sectional study

BACKGROUND

Human Immunodeficiency Virus self-test (HIVST) refers to a process where a person collects his or her own specimen (blood or oral), performs a test and interprets the results. The interpretation of results can either be done in private or through support of a trusted partner. Self-test should be seen as screening and confirmatory tests are typically strongly encouraged.

STUDY OBJECTIVE

To determine facilitating factors for HIVST acceptability and uptake among men who have sex with men (MSM).

METHODS

A cross-sectional exploratory study design, targeting MSM in Nairobi was used. Adult men (aged 18-60 years) who reported to be actively engaging in anal or oral sex with men were eligible for the study. Purposive sampling was used to identify the sites where data was collected, snowballing technique was then employed to reach the respondents. Data was collected between July 2018 and June 2019. A total of 391 MSM respondent were recruited of whom 345 MSM completed the questionnaires. The missing data was handled through the listwise approach that omits those cases with the missing data and analyze the remaining data. We also excluded responses with inconsistencies in all confirmatory questions in the questionnaire.

RESULTS

Two-thirds (64.0%) of the participants were aged 18-24 years with 13.4% being married to women and 40.2% having tertiary level of education. Majority, 72.7% were unemployed and two-thirds (64.0%) of participants were young (18-24 years) and self reported as male sex workers (58.8). There were significant associations between willingness to undertake HIV self-tests and frequency of HIV testing as well as with previous knowledge about self-testing. Habitual HIV testers were more likely to have used the HIVST kit than the non-habitual testers. Willingness to undertake confirmatory test within one month of self-testing was associated with acceptability of HIVST. Most of the MSM preferred blood sample self-test kits as compared to oral self-test kits, believing that blood test will be more accurate than oral self-test. Other factors associated with HIVST included consistent use of protection regardless of HIV status, preference of "treatment buddies". High costs of the self-test kits and inadequate knowledge on the use of HIV self-test kits were the main hindrances to HIVST uptake.

CONCLUSIONS

This study has showed that age, habitual testing, self-care/partner care, as well as confirmatory testing and immediate introduction into care if found sero-positive were associated with the use of HIVST kit. This study contributes to the pool of knowledge of the characteristics of MSM that would adopt and embrace HIVST, and demonstrates that these MSM are self and partner care aware and conscious. The challenge however remains on how to encourage those that are not self/partner care aware to embrace HIV testing and particularly HIVST as routine practices. Future studies may need to explore potential motivators to self-testing among the young, elder MSM generations and the MSM with higher economic status in Kenya.

Feasibility of conducting HIV prevention trials among key populations in Nairobi, Kenya

OBJECTIVE

To assess the feasibility of conducting HIV prevention trials among key populations in Nairobi, Kenya.

BACKGROUND

HIV prevention trials require the inclusion of those at high risk of HIV infection and their informed decision to take part and remain in the clinical trial to the end is crucial. In Kenya key populations including men who have sex with men (MSM) and female sex workers (FSW) are, disproportionately, at high risk of HIV infection when compared to the general population. Few trials testing biomedical prevention products against HIV have enrolled Kenyan FSW and MSM.

METHODS

We performed simulated vaccine efficacy trial (SiVET) using licensed hepatitis B vaccines as substitutes for a HIV vaccine candidate and included randomization for those immune to hep B. The SiVET was an observational study designed to mimic the rigors of a clinical trial; we assessed HIV risk, provided risk counselling and prevention tools and performed HIV testing at baseline and periodically until the end of the trial. MSM and FSW were enrolled at a ratio of 4:1. Volunteers were assigned to either hepatitis B vaccine or placebo.

RESULTS

Recruitment took approximately 24 months between Sep 2015 and Sep 2017. Of the 368 volunteers screened, 250 (200 MSM and 50 FSW) were enrolled. Reasons for exclusion at screening included: being positive for HIV (n = 7), hepatitis (n = 14), other pre-existing medical conditions (n = 41), eligible but chose not to enrol (n = 47). Most of the volunteers adhered to study procedures and attended their study visits within the study window. These include volunteers who received the second vaccination 244 (98%), the third vaccination 228 (91%) and, the final study visit 217 (87%). The reasons volunteers discontinued from the study early included: relocation and loss to follow up (n = 14). A total of 8 cases of HIV infection were observed in 174.5 Person Years at Risk (PYAR), all among MSM, including 5 seroconversions identified at the last study visit, for a HIV incidence of 4.58 cases/ 100 PYAR, among MSM enrolled in the study.

CONCLUSION

Our findings suggest that it is possible to conduct HIV prevention trials among key populations in Nairobi with a good adherence to a vaccine efficacy trial schedule. Despite HIV prevention efforts, we also noted a high incidence of HIV infection. This demonstrates the need for effective HIV prevention products in these populations.

A BAYESIAN HIERARCHICAL MODEL FOR COMBINING MULTIPLE DATA SOURCES IN POPULATION SIZE ESTIMATION

To combat the HIV/AIDS pandemic effectively, targeted interventions among certain key populations play a critical role. Examples of such key populations include sex workers, people who inject drugs, and men who have sex with men. While having accurate estimates for the size of these key populations is important, any attempt to directly contact or count members of these populations is difficult. As a result, indirect methods are used to produce size estimates. Multiple approaches for estimating the size of such populations have been suggested but often give conflicting results. It is, therefore, necessary to have a principled way to combine and reconcile these estimates. To this end, we present a Bayesian hierarchical model for estimating the size of key populations that combines multiple estimates from different sources of information. The proposed model makes use of multiple years of data and explicitly models the systematic error in the data sources used. We use the model to estimate the size of people who inject drugs in Ukraine. We evaluate the appropriateness of the model and compare the contribution of each data source to the final estimates.

Programmatic mapping and estimating the population size of female sex workers, men who have sex with men, people who inject drugs and transgender populations in Kenya

Introduction: Effective coverage of Human Immunodeficiency Virus prevention services for Key Populations (KPs) including female sex workers (FSWs), men who have sex with men (MSM), people who inject drugs (PWID) and transgender (TG) people necessitates periodic validation of physical venues and size estimates. Kenya conducted a robust size estimation of KPs in 2012 and a repeat mapping and size estimation exercise was conducted in 2018 to update KP Size Estimates and sub-typologies within each County for calculation of realistic program indicators.  Methods: A prospective mixed methods programmatic mapping approach adopted comprised two steps. The first step involved consolidating and documenting all known venues where KPs congregate while the second step included visiting and validating these venues confirming their active status. Data were collected in 34 out of 47 Counties in Kenya between January and March 2018. Data collected included estimated number of KPs (range), venue typology and timing of operation of each venue.   Results: We estimated a total number of 167,940 (129,271 to 206,609) FSWs; 32,580 (24,704 to 40,455) MSM; 16,063 (12,426 to 19,691) PWIDs; 10,951 (8,160 to 13,742) and 4,305 (2,826 to 5,783) transgender people congregating at 10,250, 1,729, 401 and 1,202 venues respectively. Majority of the venues for FSW (81%), MSM (64%) and transgender people (67%) were bars with and without lodging, PWIDs were mostly found on streets and injecting dens (70%).  Around 9% of FSW and MSM and11% of PWIDs were below the age of 18 years.  Conclusion: This study provided information on young KPs, female PWIDs, MSWs and for the first time, TG people in Kenya. The exercise updated size estimates of KPs by typology and provided new evidence for resource allocation, planning of interventions and targets. Programmatic mapping continues to be a useful approach supporting programs to achieve high levels of coverage and prioritize resources.

A systematic review of substance use and substance use disorder research in Kenya

Objectives

The burden of substance use in Kenya is significant. The objective of this study was to systematically summarize existing literature on substance use in Kenya, identify research gaps, and provide directions for future research.

Methods

This systematic review was conducted in line with the PRISMA guidelines. We conducted a search of 5 bibliographic databases (PubMed, PsychINFO, Web of Science, Cumulative Index of Nursing and Allied Professionals (CINAHL) and Cochrane Library) from inception until 20 August 2020. In addition, we searched all the volumes of the official journal of the National Authority for the Campaign Against Alcohol & Drug Abuse (the African Journal of Alcohol and Drug Abuse). The results of eligible studies have been summarized descriptively and organized by three broad categories including: studies evaluating the epidemiology of substance use, studies evaluating interventions and programs, and qualitative studies exploring various themes on substance use other than interventions. The quality of the included studies was assessed with the Quality Assessment Tool for Studies with Diverse Designs.

Results

Of the 185 studies that were eligible for inclusion, 144 investigated the epidemiology of substance use, 23 qualitatively explored various substance use related themes, and 18 evaluated substance use interventions and programs. Key evidence gaps emerged. Few studies had explored the epidemiology of hallucinogen, prescription medication, ecstasy, injecting drug use, and emerging substance use. Vulnerable populations such as pregnant women, and persons with physical disability had been under-represented within the epidemiological and qualitative work. No intervention study had been conducted among children and adolescents. Most interventions had focused on alcohol to the exclusion of other prevalent substances such as tobacco and cannabis. Little had been done to evaluate digital and population-level interventions.

Conclusion

The results of this systematic review provide important directions for future substance use research in Kenya.

Systematic review registration

PROSPERO: CRD42020203717.

Detection of metronidazole resistance in Trichomonas vaginalis using uncultured vaginal swabs

Trichomonas vaginalis (T. vaginalis) is the most prevalent sexually transmitted infection (STI) globally. Metronidazole is the drug of choice for treating T. vaginalis infections although metronidazole-resistant T. vaginalis has been reported in clinical isolates. The purpose of this study was to determine the presence of mutations in nitroreductase genes associated with metronidazole resistance in vaginal swabs testing positive for T. vaginalis. This study included 385 human immunodeficiency virus (HIV)-positive pregnant women. Vaginal swabs were collected from consenting pregnant women and used for the detection of T. vaginalis using the TaqMan assay. From the vaginal swabs, nitroreductase genes ntr4 and ntr6 containing mutations associated with metronidazole resistance were amplified using a quantitative polymerase chain reaction (PCR) assay. To validate the PCR assay, T. vaginalis cultured isolates with known metronidazole resistance profiles were used as controls in the mutation detection assays. The prevalence of T. vaginalis in the study population was 12.2% (47/385). Mutations associated with resistance to metronidazole were detected in more than 40% of the samples tested, i.e. 21/47 (45%) and 24/47 (51%) for ntr4 and ntr6, respectively. A total of 19 samples (40%) carried mutations for both ntr4 and ntr6 genes associated with metronidazole resistance. The validation assays showed a positive correlation between phenotypic and genotypic resistance profiles. This study found a high prevalence of mutations associated with metronidazole resistance. This is concerning since metronidazole is currently used in the syndromic management of STIs in South Africa. Molecular-based assays for monitoring metronidazole resistance profiles using nitroreductase genes may serve as a feasible method for antimicrobial surveillance studies for T. vaginalis.

Prevalence of Substance Use and Its Association with Sociodemographic and Behavioral Factors among Women Who Conduct Sex Work in Kenya

Female sex workers (FSWs) in sub-Saharan Africa are a marginalized group with an increased morbidity risk. Psychoactive substance use among this group is common and increases the risk of adverse health consequences. The type of substance used, extent, and nature of use varies with different settings and regions. We examine the use of specific psychoactive substances among FSWs residing in an urban informal settlement in Nairobi. This cross-sectional study was conducted between April and August 2017. Structured questionnaires were administered in face-to-face interviews. Descriptive statistics and logistic regression were undertaken to examine prevalence, patterns, and factors associated with use of specific substances. Out of 301 FSWs, 98% reported current psychoactive substance use. The most used substance was alcohol with 95.6% of the study population reporting use in the past year. Of these, 151 (50.2%) met criteria for very high-risk drinkers. Reported current use was 61.5% for cannabis, 47.2% for khat, and 30.9% for tobacco. Factors independently associated with hazardous and harmful alcohol use included earning a higher monthly income (>USD50) and disclosure of sex work to close family and friends. There is an urgent need for preventive and curative interventions to address the high prevalence of substance use among FSW residing in high-risk urban informal settlements in Kenya.

Summarizing methods for estimating population size for key populations: a global scoping review for human immunodeficiency virus research

BACKGROUND

Estimating the population sizes of key populations(people who inject drugs, men who have sex with men, transgender persons, and commercial sex workers) is critical for understanding the overall Human Immunodeficiency Virus burden. This scoping review aims to synthesize existing methods for population size estimation among key populations, and provide recommendations for future application of the existing methods.

METHODS

Relevant studies published from 1st January 2000 to 4th August 2020 and related to key population size estimation were retrieved and 120 of 688 studies were assessed. After reading the full texts, 81 studies were further excluded. Therefore, 39 studies were included in this scoping review. Estimation methods included five digital methods, one in-person method, and four hybrid methods.

FINDING

We summarized and organized the methods for population size estimateion into the following five categories: methods based on independent samples (including capture-recapture method and multiplier method), methods based on population counting (including Delphi method and mapping method), methods based on the official report (including workbook method), methods based on social network (including respondent-driven sampling method and network scale-up method) and methods based on data-driven technologies (Bayesian estimation method, Stochastic simulation method, and Laska, Meisner, and Siegel estimation method). Thirty-six (92%) articles were published after 2010 and 23 (59%) used multiple methods. Among the articles published after 2010, 11 in high-income countries and 28 in low-income countries. A total of 10 estimated the size of commercial sex workers, 14 focused on men who have sex with men, and 10 focused on people who inject drugs.

CONCLUSIONS

There was no gold standard for population size estimation. Among 120 studies that were related to population size estimation of key populations, the most commonly used population estimation method is the multiplier method (26/120 studies). Every method has its strengths and biases. In recent years, novel methods based on data-driven technologies such as Bayesian estimation have been developed and applied in many surveys.

Data Smoothing, Extrapolation, and Triangulation

While population size data at the national and subnational levels are critical for planning and resource allocation, most PSE studies are conducted in a few selected cities and towns due to resource and time constraints. Extrapolation methods to estimate the population size for locations not included in the PSE exercise are critical to providing data for all subnational jurisdictions and the entire country as a whole. The decision on how to select cities or towns that reflect best the national picture is a critical first step. You may need to include cities or towns from areas with low, medium, or high prevalence of your target population(s). Having some data from all these (three) areas increase the power of your study and helps to better extrapolate the results to unobserved areas, and to the national level. Through this process, data smoothing of subnational data is often needed due to relatively small samples size problem. In this chapter, we describe methods that are required for smoothing subnational data, model subnational data to extrapolate estimates to regional and national levels, and triangulate findings from different size estimation methods by a Bayesian framework to produce credible estimates.

Overview of the epidemiological conditions of HIV among key populations in Africa

INTRODUCTION

Despite extraordinary progress in HIV treatment coverage and expanding access to HIV prevention services and that multiple African countries are on track in their efforts to reach 90-90-90 goals, the epidemic continues to persist, with prevalence and incidence rates too high in some parts of the continent to achieve epidemic control. While data sources are improving, and research studies on key populations in specific contexts have improved, work on understanding the HIV burdens and barriers to services for these populations remains sparse, uneven and absent altogether in multiple settings. More data have become available in the last several years, and data published in 2010 or more recently are reviewed here for each key population. This scoping review assesses the current epidemiology of HIV among key populations in Africa and the social and political environments that contribute to the epidemic, both of which suggest that without significant policy reform, these epidemics will likely continue.

RESULTS AND DISCUSSION

Across Africa, the HIV epidemic is most severe among key populations including women and men who sell or trade sex, men who have sex with men, people who inject drugs, transgender women who have sex with men and prisoners and detainees. These groups account for the majority of new infections in West and Central Africa, and an estimated 25% of new infections in East and Southern Africa, despite representing relatively small proportions of those populations. The HIV literature in Africa emphasizes that despite significant health needs, key populations experience barriers to accessing services within the healthcare and legal justice systems. Current shortcomings of surveillance systems in enumerating key populations impact the way funding mechanisms and resources are allocated and distributed. Adapting more equitable and epidemiologically sound frameworks will be necessary for current and future HIV programming investments.

CONCLUSIONS

Through this review, the available literature on HIV epidemiology among key populations in Africa brings to light a number of surveillance, programmatic and research gaps. For many communities, interventions targeting the health and security conditions continue to be minimal. Compelling evidence suggests that sweeping policy and programmatic changes are needed to effectively tackle the persistent HIV epidemic in Africa.

Estimating the Population Size of Female Sex Workers in Zimbabwe: Comparison of Estimates Obtained Using Different Methods in Twenty Sites and Development of a National-Level Estimate

National-level population size estimates (PSEs) for hidden populations are required for HIV programming and modelling. Various estimation methods are available at the site-level, but it remains unclear which are optimal and how best to obtain national-level estimates.

Size Estimation of high-risk groups for hiv infection in india based on data from national integrated bio-behavioral surveillance and targeted interventions

Background

Targeted interventions (TIs) are one of the most effective strategies to control HIV/AIDS transmission, especially among the high-risk groups (HRGs). Implementation of HIV/AIDS control strategies relies heavily on estimation of the size of HRG population. Size estimation for key populations such as female sex workers (FSWs), men who have sex with men (MSM), and injecting drug users (IDUs) is a crucial component of national HIV strategic planning.

Objective

The objective of this study was to estimate the size of FSWs, MSM, and IDUs in various states of India.

Methods

The program multiplier method was used to estimate the size of FSWs, MSM, and IDUs across the country using two distinct but overlapping data sources - Integrated Bio-Behavioral Surveillance and TI program from the same geographical area at the same time period.

Results

In India, as on 2018-2019, there were nearly 18.2 lakhs estimated FSWs accounting to 0.53% among female population aged 15-49 years, with a highest in West Bengal (4.5 lakhs); 5.7 lakhs estimated MSM accounting to 0.16% among male population aged 15-49 years, with a highest in Gujarat (0.7 lakh); and 3.9 lakhs estimated IDUs accounting to 0.11% among male population aged 15-49 years, with a highest in Uttar Pradesh (0.5 lakh).

Conclusions

The current size estimates on HRGs will support the development of projections and estimations of the HIV epidemic at national and state levels. These estimates also help in framing national guidelines such as HIV strategic planning, program design, allocation of resources, prioritizing the interventions, and monitoring and evaluation.

Evaluating the relative contribution of data sources in a Bayesian analysis with the application of estimating the size of hard to reach populations

When using multiple data sources in an analysis, it is important to understand the influence of each data source on the analysis and the consistency of the data sources with each other and the model. We suggest the use of a retrospective value of information framework in order to address such concerns. Value of information methods can be computationally difficult. We illustrate the use of computational methods that allow these methods to be applied even in relatively complicated settings. In illustrating the proposed methods, we focus on an application in estimating the size of hard to reach populations. Specifically, we consider estimating the number of injection drug users in Ukraine by combining all available data sources spanning over half a decade and numerous sub-national areas in the Ukraine. This application is of interest to public health researchers as this hard to reach population that plays a large role in the spread of HIV. We apply a Bayesian hierarchical model and evaluate the contribution of each data source in terms of absolute influence, expected influence, and level of surprise. Finally we apply value of information methods to inform suggestions on future data collection.

Population-based methods for estimating the number of men who have sex with men: a systematic review

The objective of this systematic review was to summarise population-based methods (i.e. methods that used representative data from populations) for estimating the population size of men who have sex with men (MSM), a high-risk group for HIV and other sexually transmissible infections (STIs). Studies using population-based methods to estimate the number or percentage of MSM or gay men were included. Twenty-eight studies met the inclusion criteria. Seven studies used surveillance data, 18 studies used survey data, and six studies used census data. Sixteen studies were conducted in the US, five were conducted in European countries, two were conducted in Canada, three were conducted in Australia, one was conducted in Israel, and one was conducted in Kenya. MSM accounted for 0.03-6.5% of men among all studies, and ranged from 3.8% to 6.4% in the US, from 7000 to 39100 in Canada, from 0.03% to 6.5% in European countries, and from 127947 to 182624 in Australia. Studies using surveillance data obtained the highest estimates of the MSM population size, whereas those using survey data obtained the lowest estimates. Studies also estimated the MSM population size by dimensions of sexual orientation. In studies examining these dimensions, fewer people identified as MSM than reported experience with or attraction to other men. Selection bias, differences in recall periods and sampling, or stigma could affect the estimate. It is important to have an estimate of the number of MSM to calculate disease rates, plan HIV and STI prevention efforts, and to allocate resources for this group.

Population Size Estimate of Men Who Have Sex With Men, Female Sex Workers, and People Who Inject Drugs in Mozambique: A Multiple Methods Approach

BACKGROUND

Accurate estimates of key population size are necessary to design programs and policies to prevent and reduce new HIV infections and to monitor the dynamics of the epidemic. The first bio-behavioral surveillance surveys, with population size estimation activities, were conducted in Mozambique in 2010 to 2014.

METHODS

We used multiple methods-sequential sampling, unique object, unique event, and service multipliers-to estimate the numbers of men who have sex with men (MSM), female sex workers (FSW), and people who inject drugs (PWID) living in major cities in Mozambique. Results were applied to population sizes to estimate the number of people living with HIV and those unaware of their status.

RESULTS

Our results suggest that Maputo has 5182 MSM, which constitutes 1.0% of the adult male population (plausibility bounds, 0.5%-2.6%); Beira, 1796 (1.4%, 1.0%-2.2%); and Nampula, 874 (0.6%, 0.4%-1.6%). The number of FSW population is 1514 (0.6%; plausibility bounds, 0.4%-1.6% of adult female city population) in Maputo, 2616 (2.2%, 1.3%-6.0%) in Beira, and 2052 (1.4%, 0.8%-5.9%) in Nampula. The number of people who inject drugs is 2518 (0.4%; plausibility bounds, 0.3%-0.5% of adult male city population) in Maputo and 1982 (1.2%, 0.6%-1.9%) in Nampula. People living with HIV ranged from 25 to 497 MSM, 382 to 664 FSW, and 712 to 1340 PWID, whereas people living with HIV unaware of their HIV positive serostatus ranged from 24 to 486 MSM, 327 to 552 FSW, and 265 to 468 PWID.

CONCLUSIONS

Although estimates generally fell within the range of those from the literature, the triangulation of survey and programmatic data over time will increasingly refine population size estimates and support the optimal allocation of limited resources.

Software Application Profile: The Anchored Multiplier calculator-a Bayesian tool to synthesize population size estimates

Estimating the number of people in hidden populations is needed for public health research, yet available methods produce highly variable and uncertain results. The Anchored Multiplier calculator uses a Bayesian framework to synthesize multiple population size estimates to generate a consensus estimate. Users submit point estimates and lower/upper bounds which are converted to beta probability distributions and combined to form a single posterior probability distribution. The Anchored Multiplier calculator is available as a web browser-based application. The software allows for unlimited empirical population size estimates to be submitted and combined according to Bayes Theorem to form a single estimate. The software returns output as a forest plot (to visually compare data inputs and the final Anchored Multiplier estimate) and a table that displays results as population percentages and counts. The web application 'Anchored Multiplier Calculator' is free software and is available at [http://globalhealthsciences.ucsf.edu/resources/tools] or directly at [http://anchoredmultiplier.ucsf.edu/].

Assessing Bias in Population Size Estimates Among Hidden Populations When Using the Service Multiplier Method Combined With Respondent-Driven Sampling Surveys: Survey Study

BACKGROUND

Population size estimates (PSEs) for hidden populations at increased risk of HIV, including female sex workers (FSWs), are important to inform public health policy and resource allocation. The service multiplier method (SMM) is commonly used to estimate the sizes of hidden populations. We used this method to obtain PSEs for FSWs at 9 sites in Zimbabwe and explored methods for assessing potential biases that could arise in using this approach.

OBJECTIVE

This study aimed to guide the assessment of biases that arise when estimating the population sizes of hidden populations using the SMM combined with respondent-driven sampling (RDS) surveys.

METHODS

We conducted RDS surveys at 9 sites in late 2013, where the Sisters with a Voice program (the program), which collects program visit data of FSWs, was also present. Using the SMM, we obtained PSEs for FSWs at each site by dividing the number of FSWs who attended the program, based on program records, by the RDS-II weighted proportion of FSWs who reported attending this program in the previous 6 months in the RDS surveys. Both the RDS weighting and SMM make a number of assumptions, potentially leading to biases if the assumptions are not met. To test these assumptions, we used convergence and bottleneck plots to assess seed dependence of RDS-II proportion estimates, chi-square tests to assess if there was an association between the characteristics of FSWs and their knowledge of program existence, and logistic regression to compare the characteristics of FSWs attending the program with those recruited to RDS surveys.

RESULTS

The PSEs ranged from 194 (95% CI 62-325) to 805 (95% CI 456-1142) across 9 sites from May to November 2013. The 95% CIs for the majority of sites were wide. In some sites, the RDS-II proportion of women who reported program use in the RDS surveys may have been influenced by the characteristics of selected seeds, and we also observed bottlenecks in some sites. There was no evidence of association between characteristics of FSWs and knowledge of program existence, and in the majority of sites, there was no evidence that the characteristics of the populations differed between RDS and program data.

CONCLUSIONS

We used a series of rigorous methods to explore potential biases in our PSEs. We were able to identify the biases and their potential direction, but we could not determine the ultimate direction of these biases in our PSEs. We have evidence that the PSEs in most sites may be biased and a suggestion that the bias is toward underestimation, and this should be considered if the PSEs are to be used. These tests for bias should be included when undertaking population size estimation using the SMM combined with RDS surveys.

The changing modes of human immunodeficiency virus transmission and spatial variations among women in a minority prefecture in southwest China: An exploratory study

Liangshan Yi Autonomous Prefecture in Southwest China has a high human immunodeficiency virus (HIV) prevalence rate. This study examined the changing modes of HIV transmission among women with new HIV infections and explored the spatial heterogeneities in the factors associated with heterosexual transmission in this minority region.The data consisting of women with new HIV infections from 2011 to 2014 were collected from multiple sources. New infections were identified by BED capture enzyme immunoassay. The Bayesian hierarchical model was used to estimate the proportion of women with new HIV infections via heterosexual transmission across all townships in the Prefecture. A geographically weighted regression (GWR) model was utilized to investigate spatial variations in the sociodemographic characteristics associated with the changing modes of HIV transmission.An analytical sample of 927 women with new HIV infections was constructed and utilized to investigate the changing mode of HIV transmission. The rate of heterosexual transmission among women with new HIV infections in 2011 was below 20%. However, by 2014 this rate dramatically increased to nearly 80%. Among sociodemographic characteristics, GWR results revealed significant ethnic differences in heterosexual HIV transmission between Yi women and women in other ethnic groups, with Yi women demonstrating a lower risk of infection through heterosexual transmission. However, such ethnic differences were observed only in 30% of the townships in the Prefecture. Moreover, having a primary education decreased the odds of heterosexual transmission, which was observed in about 56% of the townships. Also, being involved in occupations other than agriculture or animal husbandry and being single or married decreased the odds of HIV infection through heterosexual contact among women, which did not significantly vary across the Prefecture.Heterosexual transmission was the predominant mode of HIV transmission among women in the Prefecture, and this transformation was clearly marked by a fast-growing trend and a spatial diffusion pattern. Spatial variations also existed in sociodemographic factors that were associated with the changing modes of HIV transmission.

Population Size Estimation of Tramadol Misusers in Urban Population in Iran: Synthesis of Methods and Results

Background

Estimating the population who use drugs is essential for planning, monitoring, and evaluation of substance use prevention and treatment. This study aims to estimate the population who misuse tramadol in urban population in Iran.

Methods

We used the wisdom of the experts (WOTE) and network scale-up (NSU) methods to calculate the population of tramadol misusers in 10 provincial capitals of Iran, in 2016. The WOTE was conducted among pharmacists in drugstores and the personnel of traditional medicinal herbs stores. They guessed the best estimation of tramadol misusers population in their cities. The NSU method was conducted among the general population and participants were questioned about ever and daily, non-medical use of tramadol during last 12 months in their network. The median of the methods was used to calculate the proportion of the adult population (15-49 years old).

Findings

The population size of tramadol misusers in studied cities was 83300 [95% uncertainty limits (UL): 47960-256220]. This corresponded to 6.6 per 1000 (95% UL: 3.88-20.30) of the 15-49-year-old population. The projected number of tramadol misusers for all 31 provincial capitals was 118290 (95% UL: 68100-363130840) and 212440 (95% UL: 122310-653410) for all urban areas. NSU also estimated the number of people who misuse tramadol on daily basis. These numbers were 52000 (95% UL: 19940-176570) for studied cities, 73840 (95% UL: 28320-250740) for all 31 provincial capital cities, and 132610 (95% UL: 50860-450310) for all urban areas in Iran.

Conclusion

This study presents information on high prevalence of tramadol misuse in urban population. We need national control measures and demand reduction programs to control tramadol misuse.

Approaches to Identify Unknown HIV-Positive Men Who Have Sex with Men in Nairobi, Kenya

Kenya has been home to one of the most severe HIV/AIDS epidemics in Sub-Saharan Africa. This persistent epidemic requires interventions tailored to affected populations, particularly men who have sex with men (MSM). Given the resource constraints of many clinics and ecological challenges of Kenya, such as the illegality of sex among MSM, interventions to address HIV must strategically engage this population. This quasi-experimental pilot study of N = 497 sought to explore differences in discovering previously unknown HIV-positive MSM in Nairobi, Kenya. The study used four clinical sites to compare a social and sexual network index testing (SSNIT) strategy compared to traditional HIV screening. Clinics using the SSNIT strategy had significantly higher incidence rates of HIV diagnoses than control clinics (IRR = 3.98, p < 0.001). This study found that building upon the social and sexual networks of MSM may be one promising strategy while discovering critical cases of HIV.

Estimation of the Population Size of Men Who Have Sex With Men in Vietnam: Social App Multiplier Method

Background

Although the prevalence of HIV among men who have sex with men (MSM) in Vietnam has been increasing in recent years, there are no estimates of the population size of MSM based on tested empirical methods.

Objective

This study aimed to estimate the size of the MSM population in 12 provinces in Vietnam and extrapolate from those areas to generate a national population estimate of MSM. A secondary aim of this study was to compare the feasibility of obtaining the number of users of a mobile social (chat and dating) app for MSM using 3 different approaches.

Methods

This study used the social app multiplier method to estimate the size of MSM populations in 12 provinces using the count of users on a social app popular with MSM in Vietnam as the first data source and a questionnaire propagated through the MSM community using respondent-driven sampling as the second data source. A national estimation of the MSM population is extrapolated from the results in the study provinces, and the percentage of MSM reachable through online social networks is clarified.

Results

The highest MSM population size among the 12 provinces is estimated in Hanoi and the lowest is estimated in Binh Dinh. On average, 37% of MSM in the provinces surveyed had used the social app Jack’d in the last 30 days (95% CI 27-48). Extrapolation of the results from the study provinces with reliable estimations results in an estimated national population of 178,000 MSM (95% CI 122,000-512,000) aged 15 to 49 years in Vietnam. The percentage of MSM among adult males aged 15 to 49 years in Vietnam is 0.68% (95% CI 0.46-1.95).

Conclusions

This study is the first attempt to empirically estimate the population of MSM in Vietnam and highlights the feasibility of reaching a large proportion of MSM through a social app. The estimation reported in this study is within the bounds suggested by the Joint United Nations Programme on HIV/AIDS. This study provides valuable information on MSM population sizes in provinces where reliable estimates were obtained, which they can begin to work with in program planning and resource allocation.

Novel Approaches for Estimating Female Sex Worker Population Size in Conflict-Affected South Sudan

Background

Limited data exist describing the population size of female sex workers (FSW) in South Sudan. A population size estimation exercise among FSW was undertaken in Juba and Nimule during the Eagle Survey.

Objective

The study aimed to estimate the number of FSW in Juba and Nimule to inform resource allocation and service provision for FSW.

Methods

We utilized service and unique object multipliers, and 3-source capture-recapture methods in conjunction with a respondent-driven sampling (RDS) survey to estimate the number of FSW in Juba and Nimule. For service multiplier, the number of FSW testing for HIV in 2015 (Juba) and 2016 (Nimule) was obtained from the LINKAGES program targeting FSW. Survey participants were asked whether they had been tested for HIV by LINKAGES during the relevant period. A total of 2 separate unique object distributions were conducted in Juba and Nimule. In Nimule, these were combined to produce a 3-source capture-recapture estimate. The exercise involved distribution of key chains and bangles to FSW, documentation of the number of those who received unique objects, and questions during RDS survey to assess whether participants received unique objects.

Results

In Juba, the service multiplier method yielded an estimate of 5800 (95% CI 4927-6673) FSW. The unique object estimate (key chain and RDS participation) yielded 5306 (95% CI 4673-5939). Another estimate using RDS participation and receipt of a bangle yielded a much lower estimate of 1863 (95% CI 1776-1951), as did a 2-source estimate of key chain and bangle (2120, 95% CI 2028-2211). A 3-source capture-recapture estimate could not be produced because aggregate rather than individual level data were collected during the third capture. The multiplier estimate using key chain and RDS participation was taken as the final population estimate for FSW in Juba, which constitutes more than 6% of the female population aged 15 to 64 years.

In Nimule, the service multiplier method yielded an estimate of 9384 (95% CI 8511-10,257). The 2-source estimates for key chain and RDS yielded 6973 (95% CI 4759-9186); bangles and RDS yielded a higher estimate of 13,104 (95% CI 7101-19,106); key chains and bangles yielded a lower estimate of 1322 (95% CI 1223-1420). The 3-source capture-recapture method using Bayesian nonparametric latent-class model-based estimate yielded a population of 2694 (95% CI 1689-6945), and this was selected as the final estimate for Nimule, which constitutes nearly 40% of female population aged 15 to 64 years.

Conclusions

The service and unique object multiplier, and 3-source capture-recapture methods were successfully used to estimate the number of FSW in Nimule, whereas service and unique object multiplier methods were successfully used in Juba. These methods yielded higher than previously estimated FSW population sizes. These estimates will inform resource allocation and advocacy efforts to support services for FSW.

Estimating the Population Size of Female Sex Workers in Namibia Using a Respondent-Driven Sampling Adjustment to the Reverse Tracking Method: A Novel Approach

BACKGROUND

Key populations, including female sex workers (FSWs), are at a disproportionately high risk for HIV infection. Estimates of the size of these populations serve as denominator data to inform HIV prevention and treatment programming and are necessary for the equitable allocation of limited public health resources.

OBJECTIVE

This study aimed to present the respondent-driven sampling (RDS) adjusted reverse tracking method (RTM; RadR), a novel population size estimation approach that combines venue mapping data with RDS data to estimate the population size, adjusted for double counting and nonattendance biases.

METHODS

We used data from a 2014 RDS survey of FSWs in Windhoek and Katima Mulilo, Namibia, to demonstrate the RadR method. Information from venue mapping and enumeration from the survey formative assessment phase were combined with survey-based venue-inquiry questions to estimate population size, adjusting for double counting, and FSWs who do not attend venues. RadR estimates were compared with the official population size estimates, published by the Namibian Ministry of Health and Social Services (MoHSS), and with the unadjusted RTM.

RESULTS

Using the RadR method, we estimated 1552 (95% simulation interval, SI, 1101-2387) FSWs in Windhoek and 453 (95% SI: 336-656) FSWs in Katima Mulilo. These estimates were slightly more conservative than the MoHSS estimates-Windhoek: 3000 (1800-3400); Katima Mulilo: 800 (380-2000)-though not statistically different. We also found 75 additional venues in Windhoek and 59 additional venues in Katima Mulilo identified by RDS participants' responses that were not detected during the initial mapping exercise.

CONCLUSIONS

The RadR estimates were comparable with official estimates from the MoHSS. The RadR method is easily integrated into RDS studies, producing plausible population size estimates, and can also validate and update key population maps for outreach and venue-based sampling.

Violence, abuse and discrimination: key factors militating against control of HIV/AIDS among the LGBTI sector

The Lesbian, Gay, Bisexual, Transgender and Intersex (LGBTI) South Africans continue to face considerable challenges, including societal stigma, homophobic violence (particularly corrective rape), and high rates of sexually transmitted diseases and infections (particularly Human Immunodeficiency Virus (HIV)/AIDS) even when discrimination based on sexual orientation was outlawed by South African’s post-apartheid constitution. This study was conducted to ascertain violence, abuse and discrimination against the LGBTI sector as key factors that hinder the smooth implementation of HIV/AIDS programme among sexually minority (LGBTI) group in Walter Sisulu University, South Africa. The self-structured questionnaire was used to collect data. The study involved 3048 purposively selected participants (1285 male and 1763 female) aged 17–38 years. About 70.5% of the participants witnessed physical attack as a form of violence against people in same-gender relationship; 47.7% disagreed that violent targeted at this sexually minority group is justified. The LGBTI face challenges which include verbal insults (937, 32.4%), bullying (532, 18.4%) and name-calling (1389, 48%). Discrimination against members of the LGBTI sector was witnessed in various forms: non-acceptance (981, 33.9%), disapproval of act of homosexuals (1308, 45.2) and denial of rights (327, 11.3). Violence, abuse and discrimination which constitute stigmatisation among the LGBTI sector are received with mix feeling. Some respondents justified the use of one or more of these key elements of stigmatisation against the LGBTI (6.6%, supports violence), others condemned these acts of stigmatisation (28.8%), against discrimination). Social stigma which resulted from violence, abuse and discrimination exist in this institution and is responsible for the unwillingness of disclosure of sexual orientation among the LGBTI members. An enabling environment should be created where the LGBTI members could come out freely to access programmes targeted at the prevention and control of HIV/AIDS.

Biometrics and public health surveillance in criminalised and key populations: policy, ethics, and human rights considerations

Widespread public health surveillance efforts focused on key populations (men who have sex with men, sex workers, people who inject drugs, and others) gather data on population sizes, HIV prevalence, and other information for planning and resource allocation. Biometric identification might improve this data gathering. However, in the context of extensive criminalisation of these populations, the use of biometrics such as fingerprints raises concerns that are insufficiently addressed in current policies. These concerns include infringing privacy, exposing participants to risks of legal action or violence, biasing surveillance results, and undermining trust in the health system. We set out key ethics and human rights considerations regarding the use of biometrics in HIV surveillance among these populations, and outline a typology of jurisdictions wherein such methods might be considered, based on data about legal, political, and social environments. In this Review, we suggest that the biometrics approach is not currently likely to be appropriate in many jurisdictions.

Estimating the Size of the MSM Population in Metro Vancouver, Canada, Using Multiple Methods and Diverse Data Sources

Men who have sex with men (MSM) are disproportionately affected by HIV globally, regionally in Canada, and locally in Vancouver. Lack of reliable population size estimates of MSM impedes effective implementation of health care services and limits our understanding of the HIV epidemic. We estimated the population size of MSM residing in Metro Vancouver drawing on four data sources: the Canadian Community Health Survey (CCHS), a cross-sectional bio-behavioural MSM survey, HIV testing services data from sexually transmitted infection (STI) clinics serving MSM, and online social networking site Facebook. Estimates were calculated using (1) direct estimates from the CCHS, (2) "Wisdom of the Crowds" (WOTC), and (3) the multiplier method using data from a bio-behavioural MSM survey, clinic-based HIV testing, and online social media network site Facebook. Data sources requiring greater public disclosure of sexual orientation resulted in our mid-range population estimates (Facebook 23,760, CCHS 30,605). The WOTC method produced the lowest estimate, 10,000. The multiplier method using STI clinic HIV testing data produced the largest estimate, 41,777. The median of all estimates was 27,183, representing 2.9% of the Metro Vancouver census male adult population, with an interquartile range of 1.1-4.5%. Using multiple data sources, our estimates of the MSM population in Metro Vancouver are similar to population prevalence estimates based on population data from other industrialized nations. These findings will support understanding of the HIV burden among MSM and corresponding public health and health services planning for this key population.

Ecologies of security: On the everyday security tactics of female sex workers in Nairobi, Kenya

This paper highlights important environmental dimensions of HIV vulnerability by describing how the sex trade operates in Nairobi, Kenya. Although sex workers there encounter various forms of violence and harassment, as do sex workers globally, we highlight how they do not merely fall victim to a set of environmental risks but also act upon their social environment, thereby remaking it, as they strive to protect their health and financial interests. In so doing, we illustrate the mutual constitution of 'agency' and 'structure' in social network formations that take shape in everyday lived spaces. Our findings point to the need to expand the focus of interventions to consider local ecologies of security in order to place the local knowledges, tactics, and capacities that communities might already possess on centre stage in interventions. Planning, implementing, and monitoring interventions with a consideration of these ecologies would tie interventions not only to the risk reduction goals of global public health policy, but also to the very real and grounded financial priorities of what it means to try to safely earn a living through sex work.

Population size estimation of female sex workers in Iran: Synthesis of methods and results

INTRODUCTION

Estimating the number of key populations at risk of HIV is essential for planning, monitoring, and evaluating prevention, care, and treatment programmes. We conducted this study to estimate the number of female sex workers (FSW) in major cities of Iran.

METHODS

We used three population size estimation methods (i.e., wisdom of the crowds, multiplier method, and network scale-up) to calculate the number of FSW in 13 cities in Iran. The wisdom of the crowds and multiplier methods were integrated into a nationwide bio-behavioural surveillance survey in 2015, and the network scale-up method was included in a national survey of the general population in 2014. The median of the three methods was used to calculate the proportion of the adult female population who practice sex work in the 13 cities. These figures were then extrapolated to provide a national population size estimation of FSW across urban areas.

RESULTS

The population size of FSW was 91,500 (95% Uncertainty Intervals [UIs] 61,400-117,700), corresponding to 1.43% (95% UIs 0.96-1.84) of the adult (i.e., 15-49 year-old) female population living in these 13 cities. The projected numbers of FSW for all 31 provincial capital cities were 130,800 (95% UIs 87,800-168,200) and 228,700 (95% UIs 153,500-294,300) for all urban settings in Iran.

CONCLUSIONS

Using methods of comparable rigor, our study provided a data-driven national estimate of the population size of FSW in urban areas of Iran. Our findings provide vital information for enhancing HIV programme planning and lay a foundation for assessing the impact of harm reduction efforts within this marginalized population.

Estimating the number of female sex workers in Côte d'Ivoire: results and lessons learned

OBJECTIVE

To report on the results of three size estimations of the populations of female sex workers (FSW) in five cities in Côte d'Ivoire and on operational lessons learned, which may be relevant for key population programmes in other parts of the world.

METHODS

We applied three methods: mapping and census, capture-recapture and service multiplier. All were applied between 2008 and 2009 in Abidjan, San Pedro, Bouaké, Yamoussoukro and Abengourou.

RESULTS

Abidjan was the city with the highest number of FSW by far, with estimations between 7880 (census) and 13 714 (service multiplier). The estimations in San Pedro, Bouaké and Yamoussoukro were very similar, with figures ranging from 1160 (Yamoussoukro, census) to 1916 (San Pedro, capture-recapture). Important operational lessons were learned, including strategies for mapping, the importance of involving peer sex workers for implementing the capture-recapture and the identification of the right question for the multiplier method.

CONCLUSIONS

Successful application of three methods to estimate the population size of FSW in five cities in Côte d'Ivoire enabled us to make recommendations for size estimations of key population in low-income countries.

Theoretical and Empirical Comparisons of Methods to Estimate the Size of Hard-to-Reach Populations: A Systematic Review

Worldwide, the HIV epidemic is concentrated among hidden populations (i.e., female sex workers, men who have sex with men, and people who inject drugs). To understand the true scope and scale of the HIV epidemic, estimates of the sizes of these populations are needed. Various methods are available to enumerate hidden populations, but the degree of agreement between these methods has not been formally evaluated. We systematically reviewed the peer-reviewed literature to assess the extent to which different population size estimation methods provide the same estimate of a target population. Of the 341 studies identified from our search, 25 met our eligibility criteria. Twenty-one unique methods were documented. The service multiplier method was the most common in the review. Eighty target populations were estimated, covering 16 countries. We observed variable population size estimates, with little agreement between methods. We note trends in the relative performance of individual methods.

Using a programmatic mapping approach to plan for HIV prevention and harm reduction interventions for people who inject drugs in three South African cities

BACKGROUND

Stigma, criminalisation and a lack of data on drug use contribute to the "invisibility" of people who inject drugs (PWID) and make HIV prevention and treatment service delivery challenging. We aimed to confirm locations where PWID congregate in Cape Town, eThekwini and Tshwane (South Africa) and to estimate PWID population sizes within selected electoral wards in these areas to inform South Africa's first multi-site HIV prevention project for PWID.

METHODS

Field workers (including PWID peers) interviewed community informants to identify suspected injecting locations in selected electoral wards in each city and then visited these locations and interviewed PWID. Interviews were used to gather information about the accessibility of sterile injecting equipment, location coordinates and movement patterns. We used the Delphi method to obtain final population size estimates for the mapped wards based on estimates from wisdom of the crowd methods, the literature and programmatic data.

RESULTS

Between January and April 2015, we mapped 45 wards. Tshwane teams interviewed 39 PWID in 12 wards, resulting in an estimated number of accessible PWID ranging from 568 to 1431. In eThekwini, teams interviewed 40 PWID in 15 wards with an estimated number of accessible PWID ranging from 184 to 350. The Cape Town team interviewed 61 PWID in 18 wards with an estimated number of accessible PWID ranging between 398 and 503. Sterile needles were only available at one location. Almost all needles were bought from pharmacies. Between 80 and 86% of PWID frequented more than one location per day. PWID who reported movement visited a median of three locations a day.

CONCLUSIONS

Programmatic mapping led by PWID peers can be used effectively to identify and reach PWID and build relationships where access to HIV prevention commodities for PWID is limited. PWID reported limited access to sterile injecting equipment, highlighting an important HIV prevention need. Programmatic mapping data show that outreach programmes should be flexible and account for the mobile nature of PWID populations. The PWID population size estimates can be used to develop service delivery targets and as baseline measures.

PrEP for key populations in combination HIV prevention in Nairobi: a mathematical modelling study

BACKGROUND

The HIV epidemic in the population of Nairobi as a whole is in decline, but a concentrated sub-epidemic persists in key populations. We aimed to identify an optimal portfolio of interventions to reduce HIV incidence for a given budget and to identify the circumstances in which pre-exposure prophylaxis (PrEP) could be used in Nairobi, Kenya.

METHODS

A mathematical model was developed to represent HIV transmission in specific key populations (female sex workers, male sex workers, and men who have sex with men [MSM]) and among the wider population of Nairobi. The scale-up of existing interventions (condom promotion, antiretroviral therapy, and male circumcision) for key populations and the wider population as have occurred in Nairobi is represented. The model includes a detailed representation of a PrEP intervention and is calibrated to prevalence and incidence estimates specific to key populations and the wider population.

FINDINGS

In the context of a declining epidemic overall but with a large sub-epidemic in MSM and male sex workers, an optimal prevention portfolio for Nairobi should focus on condom promotion for male sex workers and MSM in particular, followed by improved antiretroviral therapy retention, earlier antiretroviral therapy, and male circumcision as the budget allows. PrEP for male sex workers could enter an optimal portfolio at similar levels of spending to when earlier antiretroviral therapy is included; however, PrEP for MSM and female sex workers would be included only at much higher budgets. If PrEP for male sex workers cost as much as US$500, average annual spending on the interventions modelled would need to be less than $3·27 million for PrEP for male sex workers to be excluded from an optimal portfolio. Estimated costs per infection averted when providing PrEP to all female sex workers regardless of their risk of infection, and to high-risk female sex workers only, are $65 160 (95% credible interval [CrI] $43 520-$90 250) and $10 920 (95% CrI $4700-$51 560), respectively.

INTERPRETATION

PrEP could be a useful contribution to combination prevention, especially for under-served key populations in Nairobi. An ongoing demonstration project will provide important information regarding practical aspects of implementing PrEP for key populations in this setting.

FUNDING

The Bill & Melinda Gates Foundation.

Using Population-Size Estimation and Cross-sectional Survey Methods to Evaluate HIV Service Coverage Among Key Populations in Burkina Faso and Togo

OBJECTIVES

The objective of our study was to measure progress toward the UNAIDS 90-90-90 HIV care targets among key populations in urban areas of 2 countries in West Africa: Burkina Faso and Togo.

METHODS

We recruited female sex workers (FSWs) and men who have sex with men (MSM) through respondent-driven sampling. From January to July 2013, 2738 participants were enrolled, tested for HIV, and completed interviewer-administered surveys. We used population-size estimation methods to calculate the number of people who were engaged in the HIV continuum of care.

RESULTS

HIV prevalence ranged from 0.6% (2 of 329) of MSM in Kara, Togo, to 32.9% (115 of 350) of FSWs in Bobo Dioulasso, Burkina Faso. Of those confirmed to be HIV infected, a range of 0.0% (0 of 2) of MSM in Kara to 55.7% (64 of 115) of FSWs in Bobo Dioulasso were using ART. Based on population estimates, the percentage gap between HIV-infected people who should be using ART (per the 90-90-90 targets) and those who reported using ART ranged from 31.5% among FSWs in Bobo Dioulasso to 100.0% among MSM in Kara.

CONCLUSIONS

HIV service coverage among MSM and FSWs in Burkina Faso and Togo was low in 2013. Interventions for improving engagement of these at-risk populations in the HIV continuum of care should include frequent, routine HIV testing and linkage to evidence-based HIV treatment services. Population-size estimates can be used to inform governments, policy makers, and funding agencies about where elements of HIV service coverage are most needed.

Impact of Opioid Substitution Therapy on Antiretroviral Therapy Outcomes: A Systematic Review and Meta-Analysis

This meta-analysis provides strong evidence that opioid substitution therapy improves several key outcomes of the HIV care continuum among people who inject drugs, including recruitment onto antiretroviral therapy, retention in care, adherence, and viral suppression.

Background. Human immunodeficiency virus (HIV)–infected people who inject drugs (PWID) frequently encounter barriers accessing and remaining on antiretroviral therapy (ART). Some studies have suggested that opioid substitution therapy (OST) could facilitate PWID's engagement with HIV services. We conducted a systematic review and meta-analysis to evaluate the impact of concurrent OST use on ART-related outcomes among HIV-infected PWID.

Methods. We searched Medline, PsycInfo, Embase, Global Health, Cochrane, Web of Science, and Social Policy and Practice databases for studies between 1996 to November 2014 documenting the impact of OST, compared to no OST, on ART outcomes. Outcomes considered were coverage and recruitment onto ART, adherence, viral suppression, attrition from ART, and mortality. Meta-analyses were conducted using random-effects modeling, and heterogeneity assessed using Cochran Q test and I² statistic.

Results. We identified 4685 articles, and 32 studies conducted in North America, Europe, Indonesia, and China were included. OST was associated with a 69% increase in recruitment onto ART (hazard ratio [HR], 1.69; 95% confidence interval [CI], 1.32–2.15), a 54% increase in ART coverage (odds ratio [OR], 1.54; 95% CI, 1.17–2.03), a 2-fold increase in adherence (OR, 2.14; 95% CI, 1.41–3.26), and a 23% decrease in the odds of attrition (OR, 0.77; 95% CI, .63–.95). OST was associated with a 45% increase in odds of viral suppression (OR, 1.45; 95% CI, 1.21–1.73), but there was limited evidence from 6 studies for OST decreasing mortality for PWID on ART (HR, 0.91; 95% CI, .65–1.25).

Conclusions. These findings support the use of OST, and its integration with HIV services, to improve the HIV treatment and care continuum among HIV-infected PWID.

Availability and Quality of Size Estimations of Female Sex Workers, Men Who Have Sex with Men, People Who Inject Drugs and Transgender Women in Low- and Middle-Income Countries

Objective

To assess the availability and quality of population size estimations of female sex workers (FSW), men who have sex with men (MSM), people who inject drug (PWID) and transgender women.

Methods

Size estimation data since 2010 were retrieved from global reporting databases, Global Fund grant application documents, and the peer-reviewed and grey literature. Overall quality and availability were assessed against a defined set of criteria, including estimation methods, geographic coverage, and extrapolation approaches. Estimates were compositely categorized into ‘nationally adequate’, ‘nationally inadequate but locally adequate’, ‘documented but inadequate methods’, ‘undocumented or untimely’ and ‘no data.’

Findings

Of 140 countries assessed, 41 did not report any estimates since 2010. Among 99 countries with at least one estimate, 38 were categorized as having nationally adequate estimates and 30 as having nationally inadequate but locally adequate estimates. Multiplier, capture-recapture, census and enumeration, and programmatic mapping were the most commonly used methods. Most countries relied on only one estimate for a given population while about half of all reports included national estimates. A variety of approaches were applied to extrapolate from sites-level numbers to national estimates in two-thirds of countries.

Conclusions

Size estimates for FSW, MSM, PWID and transgender women are increasingly available but quality varies widely. The different approaches present challenges for data use in design, implementation and evaluation of programs for these populations in half of the countries assessed. Guidance should be further developed to recommend: a) applying multiple estimation methods; b) estimating size for a minimum number of sites; and, c) documenting extrapolation approaches.

Underage and underserved: reaching young women who sell sex in Zimbabwe

Young women who sell sex (YWSS) in Southern Africa are highly vulnerable to HIV, as the risks of being young and female in a high prevalence setting coalesce with those of commercial sex. YWSS are less able to negotiate safe sex, more likely to have higher risk partners, and less likely to use available health services compared to older sex workers. In Zimbabwe's national HIV programme for sex workers, fewer than 1% of clients were 15-29. We developed monthly interactive workshops for YWSS based on an Activity Pack consisting of 21 sessions organised into six modules. The aim was to encourage YWSS' interaction with each other, build their trust, confidence and skills, and encourage uptake of clinical services. We conducted a process evaluation to assess programme strengths, identify challenges, and recommend changes. This paper presents findings synthesising programme records with qualitative data and discusses feasibility, acceptability, and outputs during the pilot phase. In total, 143 YWSS attended meetings and most were from the target 15-19-year-old age group. Participants enjoyed the sessions and reported improved cooperation, willingness to negotiate with clients, and self-reflection about their futures. Staff found facilitating sessions easy and activities clear and appropriate. Challenges included identifying appropriate referrals, initial recruitment of women in some sites, and managing participants' requests for financial compensation. The number of clients aged 15-19 increased at sex worker clinics in all sites. This programme is the first to target YWSS in Zimbabwe to address their disproportionately low service use. It proved feasible to staff and acceptable to participants over a one-year period. Given enhanced vulnerability of YWSS, this programme provides one workable model for reaching this underserved group.

HIV Prevalence, Estimated Incidence, and Risk Behaviors Among People Who Inject Drugs in Kenya

OBJECTIVE

HIV infection in sub-Saharan Africa increasingly occurs among people who inject drugs (PWID). Kenya is one of the first to implement a national needle and syringe program. Our study undertook a baseline assessment as part of evaluating needle and syringe program in a seek, test, treat, and retain approach.

METHODS

Participants enrolled between May and December 2012 from 10 sites. Respondent-driven sampling was used to reach 1785 PWID for HIV-1 prevalence and viral load determination and survey data.

RESULTS

Estimated HIV prevalence, adjusted for differential network size and recruitment relationships, was 14.5% in Nairobi (95% CI: 10.8 to 18.2) and 20.5% in the Coast region (95% CI: 17.3 to 23.6). Viral load (log10 transformed) in Nairobi ranged from 1.71 to 6.12 (median: 4.41; interquartile range: 3.51-4.94) and in the Coast from 1.71 to 5.88 (median: 4.01; interquartile range: 3.44-4.72). Using log10 viral load 2.6 as a threshold for HIV viral suppression, the percentage of HIV-infected participants with viral suppression was 4.2% in Nairobi and 4.6% in the Coast. Heroin was the most commonly injected drug in both regions, used by 93% of participants in the past month, typically injecting 2-3 times/day. Receptive needle/syringe sharing at last injection was more common in Nairobi (23%) than in the Coast (4%). Estimated incidence among new injectors was 2.5/100 person-years in Nairobi and 1.6/100 person-years in the Coast.

CONCLUSIONS

The HIV epidemic is well established among PWID in both Nairobi and Coast regions. Public health scale implementation of combination HIV prevention has the potential to greatly limit the epidemic in this vulnerable and bridging population.

Population Size Estimation of Men Who Have Sex with Men in Tbilisi, Georgia; Multiple Methods and Triangulation of Findings

INTRODUCTION

An accurate estimation of the population size of men who have sex with men (MSM) is critical to the success of HIV program planning and to monitoring of the response to epidemic as a whole, but is quite often missing. In this study, our aim was to estimate the population size of MSM in Tbilisi, Georgia and compare it with other estimates in the region.

METHODS

In the absence of a gold standard for estimating the population size of MSM, this study reports a range of methods, including network scale-up, mobile/web apps multiplier, service and unique object multiplier, network-based capture-recapture, Handcock RDS-based and Wisdom of Crowds methods. To apply all these methods, two surveys were conducted: first, a household survey among 1,015 adults from the general population, and second, a respondent driven sample of 210 MSM. We also conducted a literature review of MSM size estimation in Eastern European and Central Asian countries.

RESULTS

The median population size of MSM generated from all previously mentioned methods was estimated to be 5,100 (95% Confidence Interval (CI): 3,243~9,088). This corresponds to 1.42% (95%CI: 0.9%~2.53%) of the adult male population in Tbilisi.

CONCLUSION

Our size estimates of the MSM population (1.42% (95%CI: 0.9%~2.53%) of the adult male population in Tbilisi) fall within ranges reported in other Eastern European and Central Asian countries. These estimates can provide valuable information for country level HIV prevention program planning and evaluation. Furthermore, we believe, that our results will narrow the gap in data availability on the estimates of the population size of MSM in the region.

"In the fell clutch of circumstance": HIV and men who have sex with men in sub-Saharan Africa

Men who have sex with men (MSM) in sub-Saharan Africa (SSA) have been repeatedly found to have high risk of HIV infection, and in spite of the differing nature of the HIV epidemic in the general population between East and Southern Africa, and West and Central Africa, MSM are disproportionately affected by HIV across the entire region. Recent research has examined the drivers of HIV risk, and the dynamics of the MSM HIV epidemic in greater detail. However, this growing knowledge has generally not been translated into effective HIV prevention interventions. In part, this is due to the highly stigmatised and frequently criminalised nature of same-sex sexualities in much of the region. Without human-rights-based advocacy targeting governments and interventions aiming to decrease stigma and homophobia, translating research into effective HIV interventions for MSM in SSA at the scale needed to reduce HIV transmission in this population remains highly unlikely.

Risk of sexual, physical and verbal assaults on men who have sex with men and female sex workers in coastal Kenya

BACKGROUND

Violence toward MSM and female sex workers (FSW) is associated with HIV risk, and its prevention is prioritized in international HIV/AIDS policy.

METHODS

Sociodemographic and behavioural data derived from HIV risk and follow-up cohorts including MSM and FSW in coastal Kenya between 2005 and 2014 was used to estimate the risk of rape, physical assault and verbal abuse, and to assess associations between first occurrence of assault with individual and recent behavioural factors.

RESULTS

Incidence of first reported rape was similar for MSM [3.9, confidence interval (CI) 3.1-5.0 per 100 person-years (pyrs)] and FSW (4.8 CI 3.5-6.4 per 100 pyrs), P = 0.22. Incidence of first reported physical and verbal assault was higher for FSW than MSM (21.1 versus 12.9 per 100 pyrs, P = 0.14 and 51.3 versus 30.9 per 100 pyrs, P = 0.03 respectively). Recent alcohol use was associated with reporting of all forms of assault by MSM [adjusted odds ratio (AOR) 1.8, CI 0.9-3.5] and FSW (AOR 4.4, CI 1.41-14.0), as was recent sale of sex for MSM (AOR 2.0, CI 1.1-3.8). Exclusive sex with men, active sex work, and group sex were also specifically associated with reporting rape for MSM. Perpetrators of sexual and verbal assault were usually unknown, whilst perpetrators of physical violence toward FSW were usually regular sexual partners.

CONCLUSION

MSM and FSW experienced a similarly high incidence of sexual assault in coastal Kenya, in addition to physical and verbal assault. Current national policies focus heavily on gender-based violence against women and young girls, but need to be inclusive of MSM and FSW.

Application of Network Scale Up Method in the Estimation of Population Size for Men Who Have Sex with Men in Shanghai, China

BACKGROUND

Men who have sex with men (MSM) are at high risk of HIV infection. For developing proper interventions, it is important to know the size of MSM population. However, size estimation of MSM populations is still a significant public health challenge due to high cost, hard to reach and stigma associated with the population.

OBJECTIVES

We aimed to estimate the social network size (c value) in general population and the size of MSM population in Shanghai, China by using the net work scale-up method.

METHODS

A multistage random sampling was used to recruit participants aged from 18 to 60 years who had lived in Shanghai for at least 6 months. The "known population method" with adjustment of backward estimation and regression model was applied to estimate the c value. And the MSM population size was further estimated using an adjusted c value taking into account for the transmission effect through social respect level towards MSM.

RESULTS

A total of 4017 participants were contacted for an interview, and 3907 participants met the inclusion criterion. The social network size (c value) of participants was 236 after adjustment. The estimated size of MSM was 36354 (95% CI: 28489-44219) for the male Shanghaies aged 18 to 60 years, and the proportion of MSM among the total male population aged 18 to 60 years in Shanghai was 0.28%.

CONCLUSIONS

We employed the network scale-up method and used a wide range of data sources to estimate the size of MSM population in Shanghai, which is useful for HIV prevention and intervention among the target population.

Prevalence and Correlates of HIV Infection among Street Boys in Kisumu, Kenya

Introduction

Despite their perceived vulnerability to HIV, East African street youth have been neglected in HIV prevention research. We examined HIV seroprevalence and correlates of HIV infection in a sample of male street youth in Kisumu, Kenya.

Methods

We enrolled a street-recruited sample of 13–21 year old street youth. Participants completed a survey followed by voluntary HIV counseling and testing. Survey items included demographics, homelessness history, survival activities, sexual behavior and substance use. We examined the relationship between predictor variables, markers of coercion and marginalization and HIV.

Results

The sample included 296 males. Survival activities included garbage picking (55%), helping market vendors (55%), begging (17%), and working as porters (46%) or domestic workers (4%). Forty-nine percent of participants reported at least weekly use of alcohol and 32% marijuana. Forty-six percent of participants reported lifetime inhalation of glue and 8% fuel. Seventy-nine percent of participants reported lifetime vaginal sex, 6% reported lifetime insertive anal sex and 8% reported lifetime receptive anal sex. Twelve (4.1%; 95% CI: 2.3–7.0) participants tested positive for HIV. Of those, all had been on the street for at least one year and all had engaged in vaginal sex. Occupations placing youth at particular risk of coercion by adults, including helping market vendors (prevalence ratio (PR) = 8.8; 95% CI: 1.2–67.5) and working as domestic workers (PR = 4.6; 95% CI: 1.1–19.0), were associated with HIV infection. Both insertive anal sex (PR = 10.2; 95% CI: 3.6–29.4) and receptive anal sex (PR = 3.9; 95% CI: 1.1–13.4) were associated with HIV infection. Drug use, begging, and garbage picking were not associated with HIV infection.

Conclusions

Although HIV prevalence in our sample of street youth is comparable to that of similarly-aged male youth in Nyanza Province, our findings highlight behavioral factors associated with HIV infection that offer opportunities for targeted prevention among street youth in East Africa.

Emerging themes for sensitivity training modules of African healthcare workers attending to men who have sex with men: a systematic review

Sensitivity training of front-line African health care workers (HCWs) attending to men who have sex with men (MSM) is actively promoted through national HIV prevention programming in Kenya. Over 970 Kenyan-based HCWs have completed an eight-modular online training free of charge (http://www.marps-africa.org) since its creation in 2011. Before updating these modules, we performed a systematic review of published literature of MSM studies conducted in sub-Saharan Africa (sSA) in the period 2011-2014, to investigate if recent studies provided: important new knowledge currently not addressed in existing online modules; contested information of existing module topics; or added depth to topics covered already. We used learning objectives of the eight existing modules to categorise data from the literature. If data could not be categorised, new modules were suggested. Our review identified 142 MSM studies with data from sSA, including 34 studies requiring module updates, one study contesting current content, and 107 studies reinforcing existing module content. ART adherence and community engagement were identified as new modules. Recent MSM studies conducted in sSA provided new knowledge, contested existing information, and identified new areas of MSM service needs currently unaddressed in the online training.

Antiretroviral treatment coverage for men who have sex with men and female sex workers living with HIV in Cameroon

BACKGROUND

Men who have sex with men (MSM) and female sex workers (FSW) are more likely to be living with HIV and experience difficulty accessing HIV health services due to stigma and discrimination. Antiretroviral treatment and sustained viral suppression among individuals living with HIV is the last step in the continuum of HIV care, which has been shown to improve health outcomes and decrease the risk of onward transmission of HIV.

METHODS

To calculate the numerator and denominator for antiretroviral therapy (ART) coverage estimates among MSM and FSW living with HIV, the Priority Locations for AIDS Control Efforts methods were modified to include individual quantitative interviews, health service assessment and mapping, and size estimation in 7 cities in Cameroon. MSM and FSW were recruited using peer referral and venue-based sampling. The numerator was calculated from interviews with MSM and FSW. Population size estimation of MSM and FSW was used to determine the denominator.

RESULTS

Antiretroviral coverage varied by site from 0% to 25% among HIV infected MSM and FSW. ART provision to the general population was reported at a significantly greater proportion of HIV health centers (56.5%) than ART provision to MSM and FSW populations (13.2%).

CONCLUSIONS

The majority of MSM and FSW living with HIV and eligible for treatment in Cameroon are not connected to ART care. Additionally, ART provision for MSM and FSW at HIV health centers is insufficient. Characterizing effective strategies to reach optimal levels of engagement in the continuum of HIV care among MSM and FSW is essential for an AIDS-free generation for Cameroon.

Is the promise of methadone Kenya's solution to managing HIV and addiction? A mixed-method mathematical modelling and qualitative study

BACKGROUND AND OBJECTIVES

Promoted globally as an evidence-based intervention in the prevention of HIV and treatment of heroin addiction among people who inject drugs (PWID), opioid substitution treatment (OST) can help control emerging HIV epidemics among PWID. With implementation in December 2014, Kenya is the third Sub-Saharan African country to have introduced OST. We combine dynamic mathematical modelling with qualitative sociological research to examine the 'promise of methadone' to Kenya.

METHODS, SETTING AND PARTICIPANTS

We model the HIV prevention impact of OST in Nairobi, Kenya, at different levels of intervention coverage. We draw on thematic analyses of 109 qualitative interviews with PWID, and 43 with stakeholders, to chart their narratives of expectation in relation to the promise of methadone.

RESULTS

The modelled impact of OST shows relatively slight reductions in HIV incidence (5-10%) and prevalence (2-4%) over 5 years at coverage levels (around 10%) anticipated in the planned roll-out of OST. However, there is a higher impact with increased coverage, with 40% coverage producing a 20% reduction in HIV incidence, even when accounting for relatively high sexual transmissions. Qualitative findings emphasise a culture of 'rationed expectation' in relation to access to care and a 'poverty of drug treatment opportunity'. In this context, the promise of methadone may be narrated as a symbol of hope-both for individuals and community-in relation to addiction recovery.

CONCLUSIONS

Methadone offers HIV prevention potential, but there is a need to better model the effects of sexual HIV transmission in mediating the impact of OST among PWID in settings characterised by a combination of generalised and concentrated epidemics. We find that individual and community narratives of methadone as hope for recovery coexist with policy narratives positioning methadone primarily in relation to HIV prevention. Our analyses show the value of mixed methods approaches to investigating newly-introduced interventions.