Genetics of Sub-Saharan African Human Population: Implications for HIV/AIDS, Tuberculosis, and Malaria.
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ABSTRACT:
SUBMITTER: Mboowa G
PROVIDER: S-EPMC4151494 | biostudies-literature | 2014
REPOSITORIES: biostudies-literature
Publications
Genetics of Sub-Saharan African Human Population: Implications for HIV/AIDS, Tuberculosis, and Malaria.
International journal of evolutionary biology 20140818
Sub-Saharan Africa has continued leading in prevalence and incidence of major infectious disease killers such as HIV/AIDS, tuberculosis, and malaria. Epidemiological triad of infectious diseases includes susceptible host, pathogen, and environment. It is imperative that all aspects of vertices of the infectious disease triad are analysed to better understand why this is so. Studies done to address this intriguing reality though have mainly addressed pathogen and environmental components of the t ...[more]
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Project description:IntroductionExtant studies universally document a positive gradient between socioeconomic status (SES) and health. A notable exception is the apparent concentration of HIV/AIDS among wealthier individuals. This paper uses data from the Demographic Health Surveys and AIDS Indicator Surveys to examine socioeconomic inequalities in HIV/AIDS prevalence in 24 sub-Saharan African (SSA) countries, the region that accounts for two-thirds of the global HIV/AIDS burden.MethodsThe relative and generalized concentration indices (RC and GC) were used to quantify wealth-based socioeconomic inequalities in HIV/AIDS prevalence for the total adult population (aged 15-49), for men and women, and in urban and rural areas in each country. Further, we decomposed the RC and GC indices to identify the determinants of socioeconomic inequalities in HIV/AIDS prevalence in each country.ResultsOur findings demonstrated that HIV/AIDS was concentrated among higher SES individuals in the majority of SSA countries. Swaziland and Senegal were the only countries in the region where HIV/AIDS was concentrated among individuals living in poorer households. Stratified analyses by gender showed HIV/AIDS was generally concentrated among wealthier men and women. In some countries, including Kenya, Lesotho Uganda, and Zambia, HIV/AIDS was concentrated among the poor in urban areas but among wealthier adults in rural areas. Decomposition analyses indicated that, besides wealth itself (median = 49%, interquartile range [IQR] = 90%), urban residence (median = 54%, IQR = 81%) was the most important factor contributing to the concentration of HIV/AIDS among wealthier participants in SSA countries.ConclusionsFurther work is needed to understand the mechanisms explaining the concentration of HIV/AIDS among wealthier individuals and urban residents in SSA. Higher prevalence of HIV/AIDS could be indicative of better care and survival among wealthier individuals and urban adults, or reflect greater risk behaviour and incidence. Moreover, differential findings across countries suggest that effective intervention efforts for reducing the burden of HIV/AIDS in the SSA should be country specific.
| S-EPMC3930550 | biostudies-literature
Project description:BackgroundWe examined the epidemiology and transmission potential of HIV population viral load (VL) in 12 sub-Saharan African countries.MethodsWe analyzed data from Population-based HIV Impact Assessments (PHIAs), large national household-based surveys conducted between 2015 and 2019 in Cameroon, Cote d'Ivoire, Eswatini, Kenya, Lesotho, Malawi, Namibia, Rwanda, Tanzania, Uganda, Zambia, and Zimbabwe. Blood-based biomarkers included HIV serology, recency of HIV infection, and VL. We estimated the number of people living with HIV (PLHIV) with suppressed viral load (<1,000 HIV-1 RNA copies/mL) and with unsuppressed viral load (viremic), the prevalence of unsuppressed HIV (population viremia), sex-specific HIV transmission ratios (number female incident HIV-1 infections/number unsuppressed male PLHIV per 100 persons-years [PY] and vice versa) and examined correlations between a variety of VL metrics and incident HIV. Country sample sizes ranged from 10,016 (Eswatini) to 30,637 (Rwanda); estimates were weighted and restricted to participants 15 years and older.ResultsThe proportion of female PLHIV with viral suppression was higher than that among males in all countries, however, the number of unsuppressed females outnumbered that of unsuppressed males in all countries due to higher overall female HIV prevalence, with ratios ranging from 1.08 to 2.10 (median: 1.43). The spatial distribution of HIV seroprevalence, viremia prevalence, and number of unsuppressed adults often differed substantially within the same countries. The 1% and 5% of PLHIV with the highest VL on average accounted for 34% and 66%, respectively, of countries' total VL. HIV transmission ratios varied widely across countries and were higher for male-to-female (range: 2.3-28.3/100 PY) than for female-to-male transmission (range: 1.5-10.6/100 PY). In all countries mean log10 VL among unsuppressed males was higher than that among females. Correlations between VL measures and incident HIV varied, were weaker for VL metrics among females compared to males and were strongest for the number of unsuppressed PLHIV per 100 HIV-negative adults (R2 = 0.92).ConclusionsDespite higher proportions of viral suppression, female unsuppressed PLHIV outnumbered males in all countries examined. Unsuppressed male PLHIV have consistently higher VL and a higher risk of transmitting HIV than females. Just 5% of PLHIV account for almost two-thirds of countries' total VL. Population-level VL metrics help monitor the epidemic and highlight key programmatic gaps in these African countries.
| S-EPMC10292693 | biostudies-literature
Project description:Despite improved availability of simple, relatively inexpensive, and highly effective antiretroviral treatment for HIV/AIDS, the disease remains a major public health challenge for women in sub-Saharan Africa (SSA). Given the numerous barriers in access to care for women in this region, every health issue that brings them into contact with the health system should be optimized as an opportunity to integrate HIV/AIDS prevention. Because most non-condom forms of modern contraception require a clinical appointment for use, contraception appointments could provide a confidential opportunity for access to HIV counseling, testing, and referral to care. This study sought to investigate the relationship between contraceptive methods and HIV testing among women in SSA. Data from the Demographic and Health Survey from four African countries-Congo, Mozambique, Nigeria, and Uganda-was used to examine whether modern (e.g., pills, condom) or traditional (e.g., periodic abstinence, withdrawal) forms of contraception were associated with uptake of HIV testing. Data for the current analyses were restricted to 35,748 women with complete information on the variables of interest. Chi-square tests and logistic regression models were used to assess the relationship between uptake of HIV testing and respondents' baseline characteristics and contraceptive methods. In the total sample and in Mozambique, women who used modern forms of contraception were more likely to be tested for HIV compared to those who did not use contraception. This positive association was not demonstrated in Congo, Nigeria, or Uganda. That many women who access modern contraception are not tested for HIV in high HIV burden areas highlights a missed opportunity to deliver an important intervention to promote maternal and child health. Given the increasing popularity of hormonal contraception methods in low-income countries, there is an urgent need to integrate HIV counseling, testing, and treatment into family planning programs. Women on hormonal contraceptives should be encouraged to continue to use condoms for HIV-prevention.
| S-EPMC4844155 | biostudies-other
Project description:BACKGROUND:Anopheles funestus is among the major malaria vectors in Kenya and sub-Saharan Africa and has been recently implicated in persistent malaria transmission. However, its ecology and genetic diversity remain poorly understood in Kenya. METHODS:Using 16 microsatellite loci, we examined the genetic structure of An. funestus sampled from 11 locations (n = 426 individuals) across a wide geographical range in Kenya spanning coastal, western and Rift Valley areas. RESULTS:Kenyan An. funestus resolved as three genetically distinct clusters. The largest cluster (FUN1) broadly included samples from western and Rift Valley areas of Kenya with two clusters identified from coastal Kenya (FUN2 and FUN3), not previously reported. Geographical distance had no effect on population differentiation of An. funestus. We found a significant variation in the mean Plasmodium infectivity between the clusters (?2 = 12.1, df = 2, P = 0.002) and proportional to the malaria prevalence in the different risk zones of Kenya. Notably, there was variation in estimated effective population sizes between the clusters, suggesting possible differential impact of anti-vector interventions in represented areas. CONCLUSIONS:Heterogeneity among Kenyan populations of An. funestus will impact malaria vector control with practical implications for the development of gene-drive technologies. The difference in Plasmodium infectivity and effective population size between the clusters could suggest potential variation in phenotypic characteristics relating to competence or insecticide resistance. This is worth examining in future studies.
| S-EPMC6323828 | biostudies-other
Project description:Within sub-Saharan Africa, women are disproportionately at risk for acquiring and having human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). It is important to clarify whether gender inequalities in HIV prevalence in this region are explained by differences in the distributions of HIV risk factors, differences in the effects of these risk factors or some combination of both. We used an extension of the Blinder-Oaxaca decomposition approach to explain gender inequalities in HIV/AIDS in Kenya, Lesotho and Tanzania using data from the demographic and health and AIDS indicator surveys. After adjusting for covariates using Poisson regression models, female gender was associated with a higher prevalence of HIV/AIDS in Kenya [prevalence ratio (PR) = 1.73, 95% confidence interval (CI) = 1.33, 2.23 in 2003] and Lesotho (PR = 1.39, 95% CI = 1.20, 1.62 in 2004/05), but not in Tanzania. Decomposition analyses demonstrated two distinct patterns over time. In Tanzania, the gender inequality in HIV/AIDS was explained by differences in the distributions of HIV risk factors between men and women. In contrast, in Kenya and Lesotho, this inequality was partly explained by differences in the effects across men and women of measured HIV/AIDS risk factors, including socio-demographic characteristics (age and marital status) and sexual behaviours (age at first sex); these results imply that gender inequalities in HIV/AIDS would persist in Kenya and Lesotho even if men and women had similar distributions of HIV risk factors. The production of gender inequalities may vary across countries, with inequalities attributable to the unequal distribution of risk factors among men and women in some countries and the differential effect of these factors between groups in others. These different patterns have important implications for policies to reduce gender inequalities in HIV/AIDS.
| S-EPMC4186212 | biostudies-literature
Project description:BackgroundThe antiretroviral nevirapine is associated with hypersensitivity reactions in 6%-10% of patients, including hepatotoxicity, maculopapular exanthema, Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).ObjectivesTo undertake a genome-wide association study (GWAS) to identify genetic predisposing factors for the different clinical phenotypes associated with nevirapine hypersensitivity.MethodsA GWAS was undertaken in a discovery cohort of 151 nevirapine-hypersensitive and 182 tolerant, HIV-infected Malawian adults. Replication of signals was determined in a cohort of 116 cases and 68 controls obtained from Malawi, Uganda and Mozambique. Interaction with ERAP genes was determined in patients positive for HLA-C*04:01 . In silico docking studies were also performed for HLA-C*04:01 .ResultsFifteen SNPs demonstrated nominal significance ( P < 1 × 10 -5 ) with one or more of the hypersensitivity phenotypes. The most promising signal was seen in SJS/TEN, where rs5010528 ( HLA-C locus) approached genome-wide significance ( P < 8.5 × 10 -8 ) and was below HLA -wide significance ( P < 2.5 × 10 -4 ) in the meta-analysis of discovery and replication cohorts [OR 4.84 (95% CI 2.71-8.61)]. rs5010528 is a strong proxy for HLA-C*04:01 carriage: in silico docking showed that two residues (33 and 123) in the B pocket were the most likely nevirapine interactors. There was no interaction between HLA-C*04:01 and ERAP1 , but there is a potential protective effect with ERAP2 [ P = 0.019, OR 0.43 (95% CI 0.21-0.87)].ConclusionsHLA-C*04:01 predisposes to nevirapine-induced SJS/TEN in sub-Saharan Africans, but not to other hypersensitivity phenotypes. This is likely to be mediated via binding to the B pocket of the HLA-C peptide. Whether this risk is modulated by ERAP2 variants requires further study.
| S-EPMC5400091 | biostudies-literature
Project description:Youth living with HIV (YLWHIV) have an increased cancer risk. Our objective is to describe the prevalence of medical record (MR) reported suspected cancers in a contemporary cohort of YLWHIV in Uganda that was assembled through MR reviews of patients 10 to 24 years old across 35 Ugandan HIV care health facilities. Clinical data were abstracted to identify suspected cancer cases and information about HIV care. Among 3728 YLWHIV, we identified eight suspected cancer cases. The most common suspected types were Kaposi sarcoma (n=4) followed by lymphoma (n=3). Challenges encountered in data abstraction were missing data for several variables and confirmatory cancer diagnostic information. In follow-up of suspected cases referred for diagnosis at the Uganda Cancer Institute (UCI), none had diagnosis records in UCI files. In addition, ∼18% of patients (n=686) were lost-to-follow-up (LTF) defined as not having returned to the clinic in ≥183 days and three patients died from presumed Kaposi sarcoma. Although our results suggest that cancer is rare in YLWHIV, the possibility that the cancer burden is higher cannot be excluded due to incomplete information in MRs and high LTF rates. Further, our study raises concern that patients referred for diagnosis are not accessing potential life-saving care.
| S-EPMC9021330 | biostudies-literature
Project description:Given the dual epidemics of HIV and tuberculosis in sub-Saharan Africa and evidence suggesting a disproportionate burden of these diseases among detainees in the region, we aimed to investigate the epidemiology of HIV and tuberculosis in prison populations, describe services available and challenges to service delivery, and identify priority areas for programmatically relevant research in sub-Saharan African prisons. To this end, we reviewed literature on HIV and tuberculosis in sub-Saharan African prisons published between 2011 and 2015, and identified data from only 24 of the 49 countries in the region. Where data were available, they were frequently of poor quality and rarely nationally representative. Prevalence of HIV infection ranged from 2·3% to 34·9%, and of tuberculosis from 0·4 to 16·3%; detainees nearly always had a higher prevalence of both diseases than did the non-incarcerated population in the same country. We identified barriers to prevention, treatment, and care services in published work and through five case studies of prison health policies and services in Zambia, South Africa, Malawi, Nigeria, and Benin. These barriers included severe financial and human-resource limitations and fragmented referral systems that prevent continuity of care when detainees cycle into and out of prison, or move between prisons. These challenges are set against the backdrop of weak health and criminal-justice systems, high rates of pre-trial detention, and overcrowding. A few examples of promising practices exist, including routine voluntary testing for HIV and screening for tuberculosis upon entry to South African and the largest Zambian prisons, reforms to pre-trial detention in South Africa, integration of mental health services into a health package in selected Malawian prisons, and task sharing to include detainees in care provision through peer-educator programmes in Rwanda, Zimbabwe, Zambia, and South Africa. However, substantial additional investments are required throughout sub-Saharan Africa to develop country-level policy guidance, build human-resource capacity, and strengthen prison health systems to ensure universal access to HIV and tuberculsosis prevention, treatment, and care of a standard that meets international goals and human rights obligations.
| S-EPMC6182190 | biostudies-literature
Project description:Africa has the unenviable challenge of dealing with a double burden of disease: infectious diseases (IDs) such as HIV/AIDS and tuberculosis are high while non-communicable diseases (NCDs) are rapidly rising in the region. Populations with increased susceptibility to both include migrants. This review highlights the susceptibility of rural-to-urban migrants in Sub-Saharan Africa to the IDs of HIV/AIDS and tuberculosis, and to NCDs, particularly cardiovascular diseases. The disruption that occurs with migration is often accompanied by unhealthy exposures and environments. These include partaking in risky sexual practices and a subsequent greater risk for HIV infection in migrants than the general populations which contributes to the spread of the disease. Migrants frequently work and live in conditions that are poorly ventilated and overcrowded with suboptimal sanitation which increases their risk for tuberculosis. Considering that migrants have an increased risk of acquiring both HIV/AIDS and tuberculosis, and in view of the interaction between these diseases, they are likely to be at high risk for co-infection. They are also likely to facilitate the geographical spread of these infections and serve as conduits of disease dissemination to rural areas. Changes in lifestyle behaviours that accompany migration and urbanisation are exemplified primarily by shifts in physical activity and dietary patterns which promote the development of obesity, diabetes, hypertension and cardiovascular diseases. Urban living and employment is generally less physically exerting than rural routines; when migrants relocate from their rural residence they adapt to their new environment by significantly reducing their physical activity levels. Also, nutritional patterns among migrants in urban centres change rapidly with a shift to diets higher in fat, sugar and salt. Consequently, increases in weight, blood pressure and glucose levels have been reported within a year of migration. Interactions between IDs and NCDs are common; considering that migrants have an increased susceptibility to IDs and demonstrate a rapid rise in their risk for NCDs, the concurrent prevalence of both is likely in this population. There is a need for a combined strategy to combat IDs and NCDs with screening and treatment programmes geared towards this high risk group.
| S-EPMC5526364 | biostudies-literature
Project description:BackgroundScale-up of malaria interventions over the last decade have yielded a significant reduction in malaria transmission and disease burden in sub-Saharan Africa. We estimated economic gradients in the distribution of these efforts and of their impacts within and across endemic countries.MethodsUsing Demographic and Health Surveys we computed equity metrics to characterize the distribution of malaria interventions in 30 endemic countries proxying economic position with an asset-wealth index. Gradients were summarized in a concentration index, tabulated against level of coverage, and compared among interventions, across countries, and against respective trends over the period 2005-2015.ResultsThere remain broad differences in coverage of malaria interventions and their distribution by wealth within and across countries. In most, economic gradients are lacking or favor the poorest for vector control; malaria services delivered through the formal healthcare sector are much less equitable. Scale-up of interventions in many countries improved access across the wealth continuum; in some, these efforts consistently prioritized the poorest. Expansions in control programs generally narrowed coverage gaps between economic strata; gradients persist in countries where growth was slower in the poorest quintile or where baseline inequality was large. Despite progress, malaria is consistently concentrated in the poorest, with the degree of inequality in burden far surpassing that expected given gradients in the distribution of interventions.ConclusionsEconomic gradients in the distribution of interventions persist over time, limiting progress toward equity in malaria control. We found that, in countries with large baseline inequality in the distribution of interventions, even a small bias in expansion favoring the least poor yielded large gradients in intervention coverage while pro-poor growth failed to close the gap between the poorest and least poor. We demonstrated that dimensions of disadvantage compound for the poor; a lack of economic gradients in the distribution of malaria services does not translate to equity in coverage nor can it be interpreted to imply equity in distribution of risk or disease burden. Our analysis testifies to the progress made by countries in narrowing economic gradients in malaria interventions and highlights the scope for continued monitoring of programs with respect to equity.
| S-EPMC5646111 | biostudies-literature