Adult HIV Incidence Research Articles

Declining HIV incidence in sub-Saharan Africa: a systematic review and meta-analysis of empiric data.

IntroductionUNAIDS models suggest HIV incidence is declining in sub‐Saharan Africa. The objective of this study was to assess whether modelled trends are supported by empirical evidence.MethodsWe conducted a systematic review and meta‐analysis of adult HIV incidence data from sub‐Saharan Africa by searching Embase, Scopus, PubMed and OVID databases and technical reports published between 1 January 2010 and 23 July 2019. We included prospective and cross‐sectional studies that directly measured incidence from blood samples. Incidence data were abstracted according to population risk group, geographic location, sex, intervention arm and calendar period. Weighted regression models were used to assess incidence trends across general population studies by sex. We also identified studies reporting greater than or equal to three incidence measurements since 2010 and assessed trends within them.ResultsTotal 291 studies, including 22 sub‐Saharan African countries, met inclusion criteria. Most studies were conducted in South Africa (n = 102), Uganda (n = 46) and Kenya (n = 41); there were 26 countries with no published incidence data, most in western and central Africa. Data were most commonly derived from prospective observational studies (n = 163; 56%) and from geographically defined populations with limited demographic or risk‐based enrolment criteria other than age (i.e., general population studies; n = 151; 52%). Across general population studies, average annual incidence declines since 2010 were 0.12/100 person‐years (95% CI: 0.06–0.18; p = 0.001) among men and 0.10/100 person‐years (95% CI: −0.02–0.22; p = 0.093) among women in eastern Africa, and 0.25/100 person‐years (95% CI: 0.17–034; p < 0.0001) among men and 0.42/100 person‐years (95% CI: 0.23–0.62; p = 0.0002) among women in southern Africa. In nine of 10 studies with multiple measurements, incidence declined over time, including in two studies of key populations. Across all population risk groups, the highest HIV incidence estimates were observed among men who have sex with men, with rates ranging from 1.0 to 15.4/100 person‐years. Within general population studies, incidence was typically higher in women than men with a median female‐to‐male incidence rate ratio of 1.47 (IQR: 1.11 to 1.83) with evidence of a growing sex disparity over time.ConclusionsEmpirical incidence data show the rate of new HIV infections is declining in eastern and southern Africa. However, recent incidence data are non‐existent or very limited for many countries and key populations.

Population-Based HIV Impact Assessments Survey Methods, Response, and Quality in Zimbabwe, Malawi, and Zambia.

The population-based HIV impact assessment (population-based HIV impact assessments) surveys are among the first to estimate national adult HIV incidence, subnational prevalence of viral load suppression, and pediatric HIV prevalence. We summarize the survey methods implemented in Zimbabwe, Malawi, and Zambia, as well as response rates and quality metrics. Each cross-sectional, household-based survey used a 2-stage cluster design. Survey preparations included sample design, questionnaire development, tablet programming for informed consent and data collection, community mobilization, establishing a network of satellite laboratories, and fieldworker training. Interviewers collected demographic, behavioral, and clinical information using tablets. Blood was collected for home-based HIV testing and counseling (HBTC) and point-of-care CD4+ T-cell enumeration with results immediately returned. HIV-positive blood samples underwent laboratory-based confirmatory testing, HIV incidence testing, RNA polymerase chain reaction (viral load), DNA polymerase chain reaction (early infant diagnosis), and serum antiretroviral drug detection. Data were weighted for survey design, and chi square automatic interaction detection-based methods were used to adjust for nonresponse. Each survey recruited a nationally representative, household-based sample of children and adults over a 6-10-month period in 2015 and 2016. Most (84%-90%) of the 12,000-14,000 eligible households in each country participated in the survey, with 77%-81% of eligible adults completing an interview and providing blood for HIV testing. Among eligible children, 59%-73% completed HIV testing. Across the 3 surveys, 97.8% of interview data were complete and had no errors. Conducting a national population-based HIV impact assessment with immediate return of HIV and other point-of-care test results was feasible, and data quality was high.

Large age shifts in HIV-1 incidence patterns in KwaZulu-Natal, South Africa

Recent declines in adult HIV-1 incidence have followed the large-scale expansion of antiretroviral therapy and primary HIV prevention across high-burden communities of sub-Saharan Africa. Mathematical modeling suggests that HIV risk will decline disproportionately in younger adult age-groups as interventions scale, concentrating new HIV infections in those >age 25 over time. Yet, no empirical data exist to support these projections. We conducted a population-based cohort study over a 16-y period (2004 to 2019), spanning the early scale-up of antiretroviral therapy and voluntary medical male circumcision, to estimate changes in the age distribution of HIV incidence in a hyperepidemic region of KwaZulu-Natal, South Africa, where adult HIV incidence has recently declined. Median age of HIV seroconversion increased by 5.5 y in men and 3.0 y in women, and the age of peak HIV incidence increased by 5.0 y in men and 2.0 y in women. Incidence declined disproportionately among young men (64% in men 15 to 19, 68% in men 20 to 24, and 46% in men 25 to 29) and young women (44% in women 15 to 19, 24% in women 20 to 24) comparing periods pre- versus post-universal test and treat. Incidence was stable (<20% change) in women aged 30 to 39 and men aged 30 to 34. Age shifts in incidence occurred after 2012 and were observed earlier in men than in women. These results provide direct epidemiological evidence of the changing demographics of HIV risk in sub-Saharan Africa in the era of large-scale treatment and prevention. More attention is needed to address lagging incidence decline among older individuals.

The effect of 90-90-90 on HIV-1 incidence and mortality in eSwatini: a mathematical modelling study

SummaryBackgroundThe rapid scale-up of antiretroviral therapy (ART) towards the UNAIDS 90-90-90 goals over the last decade has sparked considerable debate as to whether universal test and treat can end the HIV-1 epidemic in sub-Saharan Africa. We aimed to develop a network transmission model, calibrated to capture age-specific and sex-specific gaps in the scale-up of ART, to estimate the historical and future effect of attaining and surpassing the UNAIDS 90-90-90 treatment targets on HIV-1 incidence and mortality, and to assess whether these interventions will be enough to achieve epidemic control (incidence of 1 infection per 1000 person-years) by 2030.MethodsWe used eSwatini (formerly Swaziland) as a case study to develop our model. We used data on HIV prevalence by 5-year age bins, sex, and year from the 2007 Swaziland Demographic Health Survey (SDHS), the 2011 Swaziland HIV Incidence Measurement Survey, and the 2016 Swaziland Population Health Impact Assessment (PHIA) survey. We estimated the point prevalence of ART coverage among all HIV-infected individuals by age, sex, and year. Age-specific data on the prevalence of male circumcision from the SDHS and PHIA surveys were used as model inputs for traditional male circumcision and scale-up of voluntary medical male circumcision (VMMC). We calibrated our model using publicly available data on demographics; HIV prevalence by 5-year age bins, sex, and year; and ART coverage by age, sex, and year. We modelled the effects of five scenarios (historical scale-up of ART and VMMC [status quo], no ART or VMMC, no ART, age-targeted 90-90-90, and 100% ART initiation) to quantify the contribution of ART scale-up to declines in HIV incidence and mortality in individuals aged 15–49 by 2016, 2030, and 2050.FindingsBetween 2010 and 2016, status-quo ART scale-up among adults (aged 15–49 years) in eSwatini (from 34·0% in 2010 to 74·1% in 2016) reduced HIV incidence by 43·57% (95% credible interval 39·71 to 46·36) and HIV mortality by 56·17% (54·06 to 58·92) among individuals aged 15–49 years, with larger reductions in incidence among men and mortality among women. Holding 2016 ART coverage levels by age and sex into the future, by 2030 adult HIV incidence would fall to 1·09 (0·87 to 1·29) per 100 person-years, 1·42 (1·13 to 1·71) per 100 person-years among women and 0·79 (0·63 to 0·94) per 100 person-years among men. Achieving the 90-90-90 targets evenly by age and sex would further reduce incidence beyond status-quo ART, primarily among individuals aged 15–24 years (an additional 17·37% [7·33 to 26·12] reduction between 2016 and 2030), with only modest additional incidence reductions in adults aged 35–49 years (1·99% [–5·09 to 7·74]). Achieving 100% ART initiation among all people living with HIV within an average of 6 months from infection—an upper bound of plausible treatment effect—would reduce adult HIV incidence to 0·73 infections (0·55 to 0·92) per 100 person-years by 2030 and 0·46 (0·33 to 0·59) per 100 person-years by 2050.InterpretationScale-up of ART over the last decade has already contributed to substantial reductions in HIV-1 incidence and mortality in eSwatini. Focused ART targeting would further reduce incidence, especially in younger individuals, but even the most aggressive treatment campaigns would be insufficient to end the epidemic in high-burden settings without a renewed focus on expanding preventive measures.FundingGlobal Good Fund and the Bill & Melinda Gates Foundation.

The Effect of 90-90-90 on HIV-1 Incidence and Mortality in the Kingdom of Eswatini

Background: The rapid scale-up of antiretroviral therapy (ART) over the last decade has sparked considerable debate as to whether universal test and treat (UTT) can end the HIV epidemic in sub-Saharan Africa (SSA). Methods: Using the Kingdom of Eswatini as a case study, we developed a network transmission model, calibrated to capture age and gender-specific gaps in the scale-up of ART, to estimate the impact of attaining and surpassing the 90-90-90 treatment targets on HIV incidence and mortality. We compared different ART coverage scenarios to estimate reductions in incidence and mortality over time and to evaluate the potential to drive annual incidence below an epidemic control threshold of 0.1%. Findings: ART scale-up reduced HIV incidence by 43.5% (95% credible interval, 39.7 - 46.4%) and HIV mortality by 56.2% (95% CI, 54.1 - 58.9%) among adults 15-49 years of age between 2010 and 2016, with larger reductions in incidence among men and mortality among women. Holding 2016 ART coverage levels by age and gender, adult HIV incidence would fall to 1.1% (95% CI: 0.87 - 1.3%), 2.0% (95% CI: 1.5 - 2.5%) among women, and 0.9% (95% CI: 0.7 - 1.2%) among men by 2030. Achieving the 90-90-90 targets by age and gender would further reduce incidence in individuals 15-24 years of age, 17.4% (95% CI, 7.3 - 26.1%) additional incidence reduction between 2016 and 2013, with only modest additional reductions in adults overall. Achieving 100% ART initiation, an upper bound of treatment effect, would reduce adult HIV incidence to 0.7% (95% CI: 0.6 - 0.9%) by 2030 and 0.5% (95% CI: 0.3 - 0.6%) by 2050. Interpretation: Scale-up of ART over the last decade has already contributed to substantial reductions in HIV incidence and mortality. Focused ART targeting would further reduce incidence, especially in younger individuals, but even the most aggressive treatment campaigns would be insufficient to end the epidemic in high-burden settings without a renewed focus on expanding preventive measures. Funding Statement: Support provided from the Global Good Fund and the Bill and Melinda Gates Foundation. Declaration of Interests: All authors declare no competing interests. Ethics Approval Statement: Not required.

Towards 90-90: Findings after two years of the HPTN 071 (PopART) cluster-randomized trial of a universal testing-and-treatment intervention in Zambia.

BackgroundHPTN071(PopART) is a 3-arm community-randomised study in 21 peri-urban/urban communities in Zambia and the Western Cape of South Africa, with high HIV prevalence and high mobility especially among young adults. In Arm A communities, from November 2013 community HIV care providers (CHiPs) have delivered the “PopART” universal-test-and-treat (UTT) package in annual rounds, during which they visit all households and offer HIV testing. CHiPs refer HIV-positive (HIV+) individuals to routine HIV clinic services, where universal ART (irrespective of CD4 count) is offered, with re-visits to support linkage to care. The overall goal is to reduce population-level adult HIV incidence, through achieving high HIV testing and treatment coverage.Methods and findingsThe second annual round was June 2015-October 2016. Included in analysis are all individuals aged ≥15 years who consented to participate, with extrapolation to the total population. Our three main outcomes are (1) knowledge of HIV+ status (2) ART coverage, by the end of Round 2 (R2) and compared with the start of R2, and (3) retention on ART on the day of consenting to participate in R2. We used “time-to-event” methods to estimate the median time to start ART after referral to care. CHiPs visited 45,631 households during R2, ~98% of the estimated total across the four communities, and for 94% (43,022/45,631) consent was given for all household members to be listed on the CHiPs’ electronic register; 120,272 individuals aged ≥15 years were listed, among whom 64% of men (37,265/57,901) and 86% (53,516/62,371) of women consented to participate in R2. We estimated there were 6,521 HIV+ men and 10,690 HIV+ women in the total population of visited households; and that ~80% and ~90% of HIV+ men and women respectively knew their HIV+ status by the end of R2, fairly similar across age groups but lower among those who did not participate in Round 1 (R1). Among those who knew their HIV+ status, ~80% of both men and women were on ART by the end of R2, close to 90% among men aged ≥45 and women aged ≥35 years, but lower among younger adults, those who were resident in R1 but did not participate in R1, and those who were newly resident in the area of the community in which they were living in R2. Overall ART coverage was ~65% among HIV+ men and ~75% among HIV+ women, compared with the cumulative 90–90 target of 81%. Among those who reported ever taking ART, 93% of men and 95% of women self-reported they were on ART and missed 0 pills in the last 3 days. The median time to start ART after referral to care was ~6 months in R2, similar across the age range 25–54 years, compared with ~9.5 months in R1. The two main limitations to our findings were that a comparison with control-arm communities cannot be made until the end of the study; and that to extrapolate to the total population, assumptions were required about individuals who were resident, but did not participate, in R2.ConclusionsOverall coverage against the 90–90 targets was high after two years of intervention, but was lower among men, individuals aged 18–34 years, and those who did not participate in R1. Our findings reflect the relative difficulties for CHiPs to contact men at home, compared with women, and that it is challenging to reach high levels of testing and treatment coverage in communities with substantial mobility and in-migration. The shortened time to start ART after referral to care in R2, compared with R1, was likely attributable to multiple factors including an increased focus of the CHiPs on linkage to care; increasing community acceptance and understanding of the CHiPs, and of ART and UTT, with time; increased coordination with the clinics to facilitate linkage; and clinic improvements.

Diagnosing HIV Infection in Adult Patients in the Intensive Care Unit

HIV-infected adults admitted to hospitals for critical care services have unique needs the provider must recognize to deliver optimal care. Unfortunately, many of these patients are unaware of their HIV serostatus on admission to the intensive care unit (ICU), resulting in the need for more specific and tailored screening and diagnostic procedures in the ICU environment. Intensive care nurse practitioners, physicians, and physician assistants who are responsible for diagnosing and directing care in the ICU should have a solid understanding of the procedures involved in screening patients for HIV, diagnosing HIV-related diseases, and recognizing the diagnostic parameters associated with classifying HIV infection and AIDS. However, the literature on this topic is scant. We explore the procedures associated with HIV screening and diagnosis in the ICU and describe clinical procedures associated with informed consent, disclosure of serostatus to patients and families, and the classification of HIV infection and AIDS using Centers for Disease Control and Prevention (CDC) guidelines. HIV Infection in the United States HIV infection continues to be a prevalent national health problem. Most recent estimates have indicated that 1.2 million persons ages 13 years or older were living with HIV in the United States (CDC, 2012). In addition, 156,300 (12.8%) of these persons were undiagnosed (CDC, 2012). Adult HIV incidence data have shown that new infections remained higher in African Americans (49.4%), Hispanics (18.4%), and for persons of multiple races (10.6%; CDC, 2015a). Males continued to constitute the majority of diagnoses (81%; CDC, 2015a). Men who have sex with men (MSM) had a rising incidence of infection (up to 70% when including injecting drug-using MSM), while heterosexual contact was attributed to 24% of new infections (CDC, 2015a). The southern region of the United States had the highest incidence rate of infections (18.5%), with rates in the Northeast (14.2%), West (11/2%), and Midwest (8.2%) being lower. Persons ages 20 to 29 years had the highest incidence of infection (70.1%; CDC, 2015a). While specific numeric data regarding diagnoses of AIDS (Stage 3) are not reported here, they trended downward overall but were comparable in regard to race/ethnicity, sex, mode of transmission, region, and age. Similar to new diagnoses of AIDS, deaths in those with HIValso decreased in the last reporting period. However, these data included individuals whose deaths may not have been attributable to HIV. Deaths in individuals with a prior diagnosis of AIDS also decreased, with death rates in MSM, Whites, and Asians remaining stable (CDC, 2015a).

Prospects for HIV control in South Africa: a model-based analysis

BackgroundThe goal of virtual elimination of horizontal and mother-to-child HIV transmission in South Africa (SA) has been proposed, but there have been few systematic investigations of which interventions are likely to be most critical to reducing HIV incidence.ObjectiveThis study aims to evaluate SA's potential to achieve virtual elimination targets and to identify which interventions will be most critical to achieving HIV incidence reductions.DesignA mathematical model was developed to simulate the population-level impact of different HIV interventions in SA. Probability distributions were specified to represent uncertainty around 32 epidemiological parameters that could be influenced by interventions, and correlation coefficients (r) were calculated to assess the sensitivity of the adult HIV incidence rates and mother-to-child transmission rates (2015–2035) to each epidemiological parameter.ResultsHIV incidence in SA adults (ages 15–49) is expected to decline from 1.4% in 2011–2012 to 0.29% by 2035 (95% CI: 0.10–0.62%). The parameters most strongly correlated with future adult HIV incidence are the rate of viral suppression after initiating antiretroviral treatment (ART) (r=−0.56), the level of condom use in non-marital relationships (r=−0.40), the phase-in of intensified risk-reduction counselling for HIV-positive adults (r=0.29), the uptake of medical male circumcision (r=−0.24) and the phase-in of universal ART eligibility (r=0.22). The paediatric HIV parameters most strongly associated with mother-to-child transmission rates are the relative risk of transmission through breastfeeding when the mother is receiving ART (r=0.70) and the rate of ART initiation during pregnancy (r=−0.16).ConclusionsThe virtual elimination target of a 0.1% incidence rate in adults will be difficult to achieve. Interventions that address the infectiousness of patients after ART initiation will be particularly critical to achieving long-term HIV incidence declines in South Africa.

Estimating the impact of universal antiretroviral therapy for HIV serodiscordant couples through home HIV testing: insights from mathematical models.

IntroductionAntiretroviral therapy (ART) prevents HIV transmission within HIV serodiscordant couples (SDCs), but slow implementation and low uptake has limited its impact on population-level HIV incidence. Home HIV testing and counselling (HTC) campaigns could increase ART uptake among SDCs by incorporating couples’ testing and ART referral. We estimated the reduction in adult HIV incidence achieved by incorporating universal ART for SDCs into home HTC campaigns in KwaZulu-Natal (KZN), South Africa, and southwestern (SW) Uganda.MethodsWe constructed dynamic, stochastic, agent-based network models for each region. We compared adult HIV incidence after 10 years under three scenarios: (1) “Current Practice,” (2) “Home HTC” with linkage to ART for eligible persons (CD4 <350) and (3) “ART for SDCs” regardless of CD4, delivered alongside home HTC.ResultsART for SDCs reduced HIV incidence by 38% versus Home HTC: from 1.12 (95% CI: 0.98–1.26) to 0.68 (0.54–0.82) cases per 100 person-years (py) in KZN, and from 0.56 (0.50–0.62) to 0.35 (0.30–0.39) cases per 100 py in SW Uganda. A quarter of incident HIV infections were averted over 10 years, and the proportion of virally suppressed HIV-positive persons increased approximately 15%.ConclusionsUsing home HTC to identify SDCs and deliver universal ART could avert substantially more new HIV infections than home HTC alone, with a smaller number needed to treat to prevent new HIV infections. Scale-up of home HTC will not diminish the effectiveness of targeting SDCs for treatment. Increasing rates of couples’ testing, disclosure, and linkage to care is an efficient way to increase the impact of home HTC interventions on HIV incidence.

Estimating PMTCT's Impact on Heterosexual HIV Transmission: A Mathematical Modeling Analysis.

IntroductionPrevention of mother-to-child HIV transmission (PMTCT) strategies include combined short-course antiretrovirals during pregnancy (Option A), triple-drug antiretroviral treament (ART) during pregnancy and breastfeeding (Option B), or lifelong ART (Option B+). The WHO also recommends ART for HIV treatment and prevention of sexual transmission of HIV. The impact of PMTCT strategies on prevention of sexual HIV transmission of HIV is not known. We estimated the population-level impact of PMTCT interventions on heterosexual HIV transmission in southwestern Uganda and KwaZulu-Natal, South Africa, two regions with different HIV prevalence and fertility rates.Materials and MethodsWe constructed and validated dynamic, stochastic, network-based HIV transmission models for each region. PMTCT Options A, B, and B+ were simulated over ten years under three scenarios: 1) current ART and PMTCT coverage, 2) current ART and high PMTCT coverage, and 3) high ART and PMTCT coverage. We compared adult HIV incidence after ten years of each intervention to Option A (and current ART) at current coverage.ResultsAt current coverage, Options B and B+ reduced heterosexual HIV incidence by about 5% and 15%, respectively, in both countries. With current ART and high PMTCT coverage, Option B+ reduced HIV incidence by 35% in Uganda and 19% in South Africa, while Option B had smaller, but meaningful, reductions. The greatest reductions in HIV incidence were achieved with high ART and PMTCT coverage. In this scenario, all PMTCT strategies yielded similar results.DiscussionImplementation of Options B/B+ reduces adult HIV incidence, with greater effect (relative to Option A at current levels) in Uganda than South Africa. These results are likely driven by Uganda’s higher fertility rates.

Redefining the HIV epidemic in Nigeria

Background:Governments are increasingly recognizing the need to focus limited HIV resources on specific geographic areas and specific populations to have a greater impact. Nigeria, with the second largest HIV epidemic in the world, is an important example of where more localized programming has the potential to improve the efficiency of the HIV response.Methods:Using Spectrum software we modelled the Nigerian HIV epidemic using two methods: First, we created national HIV estimates using trends in urban and rural areas. Second, we created national HIV estimates using trends from each of the 37 states in Nigeria and aggregated these results. In both instances we used HIV surveillance data from antenatal clinics and household surveys and aggregated the trends to determine the national epidemic.Results:The state models showed divergent trends in the 37 states. Comparing the national results calculated from the two methods resulted in different conclusions. In the aggregated state files, adult HIV incidence in Nigeria was stable between 2005 and 2013 (change of −6%), whereas the urban and rural file suggested incidence was decreasing over the same time (change of −50%). This difference was also reflected in the HIV prevalence trends, although the two methods showed similar trends in AIDS-related mortality. The two models had similar adult HIV prevalence in 2013: 3.0% (2.0–4.5%) in the aggregated state files versus 3.2% (3.0–3.5%) in the urban/rural file.Conclusion:The state-level estimates provide insight into the variations of the HIV epidemic in each state and provide useful information for programme managers. However, the reliability of the results is highly dependent on the amount and quality of data available from each sub-national area.

Structural barriers to antiretroviral treatment: a study using population-based CD4 cell count and linked antiretroviral treatment programme data

BackgroundThe promise of an AIDS-free generation rests on treatment as prevention to reduce HIV incidence. Treatment as prevention depends critically on high antiretroviral treatment (ART) coverage. However, even under current national ART guidelines coverage remains far from universal in sub-Saharan Africa. We examined structural barriers to ART access in a community in rural South Africa, which has a very high adult HIV prevalence (28%) and incidence (approximately three new infections per 100 person-years). MethodsWe did a population-based survey of CD4 cell count among 5000 randomly selected participants in the 2010 round of a longitudinal, population-based HIV surveillance study. The study was carried out by the Africa Centre for Health and Population Studies in the Hlabisa subdistrict of KwaZula-Natal. We identified the people needing ART among the HIV-infected surveillance participants as those who were either enrolled in the local ART programme (ie, people needing and receiving ART) or people who were not enrolled in the programme but had a CD4 cell count below a certain threshold (ie, people needing ART but not yet receiving it). We applied two different CD4 cell count thresholds (≤200 and ≤350 cells per μL), leading to two different samples of people needing ART (n=376 and n=610). We then used logistic regression to explore the effect of socioeconomic factors (sex, age, education, wealth, distance to the nearest ART clinic, urban/rural residence, and migration status) on the binary outcome of ART enrolment in relation to ART need. FindingsART coverage was 72% in the 376 individuals who were either on ART or had a CD4 count of 200 cells per μL or fewer, and 45% in the 610 individuals who were either on ART or had a CD4 count of 350 cells per μL or fewer. Women who needed ART were significantly more likely to receive treatment than were men who needed it (48% vs 34%; p=0·003 for the ≤350 cells per μL threshold). The age pattern of ART coverage increased from approximately 20% at age 20 years to 60% at age 45 years, declining to 40% at age 70 years for the 350 cells per μL or fewer threshold. Controlling for other factors, among those needing ART, women were more than twice as likely to be taking ART than were men (adjusted odds ratio 2·43, 95% CI 1·36–4·33; p=0·003) and every additional km distance from the nearest clinic decreased the likelihood of ART used by approximately 20% (adjusted odds ratio 0·79, 95% CI 0·67–0·94; p=0·007). Education, wealth, and migration did not affect ART access. When we separated women into those who had not been pregnant since inception of the ART programme in 2004, and those who had been pregnant, pregnancy was a significant determinant of ART access, but explained only a small fraction (<10%) of the difference in ART access between women and men. When we used the second sample of 610 individuals, the findings remained essentially the same. InterpretationWorking towards universal coverage goals, ART programmes need to improve access for men, young and old people, and remote populations. Interventions improving geographical accessibility of ART programmes, such as subsidised transport or the opening of more ART clinics in remote areas, are likely to help to overcome important structural barriers to access. FundingThe Africa Centre for Health and Population Studies demographic and HIV surveillance is funded by the Wellcome Trust. TB and FT received financial support from the Wellcome Trust and through 1R01-HD058482-01 from the National Institute of Child Health and Human Development, National Institutes of Health.

Trends in HIV prevalence among young people in generalised epidemics: implications for monitoring the HIV epidemic

BackgroundCountries measure trends in HIV incidence to assess the impact of HIV prevention and treatment programmes. Most countries have approximated trends in HIV incidence through modelled estimates or through trends...

The role of sexually transmitted infections in the evolution of the South African HIV epidemic

To assess the extent to which sexually transmitted infections (STIs) have contributed to the spread of HIV in South Africa and to estimate the extent to which improvements in STI treatment have reduced HIV incidence. A mathematical model was used to simulate interactions between HIV and six other STIs (genital herpes, syphilis, chancroid, gonorrhoea, chlamydial infection and trichomoniasis) as well as bacterial vaginosis and vaginal candidiasis. The effects of STIs on HIV transmission probabilities were assumed to be consistent with meta-analytic reviews of observational studies, and the model was fitted to South African HIV prevalence data. The proportion of new HIV infections in adults that were attributable to curable STIs reduced from 39% (uncertainty range: 24-50%) in 1990 to 14% (8-18%) in 2010, while the proportion of new infections attributable to genital herpes increased. Syndromic management programmes are estimated to have reduced adult HIV incidence by 6.6% (3.3-10.3%) between 1994 and 2004, by which time syndromic management coverage was 52%. Had syndromic management been introduced in 1986, with immediate achievement of 100% coverage and a doubling of the rate of health seeking, HIV incidence would have reduced by 64% (36-82%) over the next decade, but had the same intervention been delayed until 2004, HIV incidence would have reduced by only 5.5% (2.8-9.0%). Sexually transmitted infections have contributed significantly to the spread of HIV in South Africa, but STI control efforts have had limited impact on HIV incidence because of their late introduction and suboptimal coverage.

The estimated burden of HIV/AIDS in Uganda, 2005–2010

To estimate the burden of HIV disease in Uganda and the effect of HIV/AIDS control programmes to mitigate it. Mathematical modelling and projecting using surveillance and census data. Using antenatal clinic surveillance (1986-2002) and a recent population-based survey (2004-2005) data, we modelled the adult national HIV prevalence over time (1981-2004), and kept prevalence constant at 6.4% for the years 2004-2010. Using Spectrum software and census data, we estimated the national burden of HIV disease and the effect of selected HIV-related prevention and treatment programmes. In 2005, we estimated that there were 135,300 new HIV infections (adult HIV incidence 0.96%), 691,900 asymptomatic prevalent infections, 88 100 AIDS cases, and 76 400 AIDS deaths. An estimated 647,000 (80%) HIV-infected adults were unaware of their infection; one third of all adult deaths were HIV related. As a result of population growth, by 2008 a similar number of people will be HIV infected (1.1 million) as during the peak of the epidemic in 1994. Although antiretroviral therapy (ART) coverage is expected to rise from 67,000 (2005) to 160,000 (2010), the number of persons needing but not receiving ART will decrease only slightly from 127,600 (2005) to 111,100 (2010). The use of single-dose in 2005 nevirapine probably averted only 4% of the estimated 20 400 vertical infections. HIV/AIDS continues to be a leading cause of adult disease and death in Uganda. Universal ART access is probably unachievable. With the absolute burden of HIV disease approaching the historic peak in the early 1990s, more effective prevention programmes are of paramount importance.

Short term estimates of adult HIV incidence by mode of transmission: Kenya and Thailand as examples

Objective: Patterns of transmission of HIV are different among different regions of the world and change over time within regions. In order to adapt prevention strategies to changing patterns of...

Type of partnership and heterosexual spread of HIV infection in rural Uganda: results from simulation modelling.

The objective was to estimate the likely percentage of HIV infections that may be attributable to one-off partnerships (such as those between female sex workers and their clients) and longer-term partnerships in rural Uganda. This was addressed by the application of a microsimulation model (SimulAIDS) of the transmission dynamics of HIV infection, drawing on data from a population cohort of 10,000 in rural Uganda. For a scenario reproducing documented characteristics of the study population in 1990, when adult HIV prevalence was 9%, and during subsequent follow up (1990-1994), when adult HIV incidence was 8 per 1000 person-years, the percentage of HIV infections in men (women) attributed to one-off partnerships decreased from 96% (26%) during 1980 to 67% (8%) in 1989 and 22% (5%) in 1994. Reducing HIV transmission between one-off partners early in an HIV epidemic may substantially limit the potential for the spread of HIV infection. At a later phase, prevention must also focus on control of transmission between longer-term HIV-discordant partners.