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2.
Vulnerable Child Youth Stud ; 12(4): 360-374, 2017 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-29170681

RESUMO

There is a growing interest in education as a means to reduce HIV infection in vulnerable children in sub-Saharan Africa; however, the mechanisms by which education reduces HIV infection remain uncertain. Substance use has been associated with high-risk sexual behaviour and could lie on the causal pathway between education and HIV risk. Therefore, we used multivariable regression to measure associations between: (i) orphanhood and substance use (alcohol, recreational drugs, and smoking), (ii) substance use and sexual risk behaviours, and (iii) school enrolment and substance use, in adolescents aged 15-19 years, in Eastern Zimbabwe. We found substance use to be low overall (6.4%, 3.2%, and 0.9% of males reported alcohol, drug, and cigarette use; <1% of females reported any substance use), but was more common in male maternal and double orphans than non-orphans. Substance use was positively associated with early sexual debut, number of sexual partners, and engaging in transactional sex, while school enrolment was associated with lower substance use in males. We conclude that education may reduce sexual risk behaviours and HIV infection rates among male adolescents in sub-Saharan Africa, in part, by reducing substance abuse.

3.
Health Promot Int ; 29(4): 645-54, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23503291

RESUMO

Little research has been conducted on how pre-existing indigenous community resources, especially social networks, affect the success of externally imposed HIV interventions. Antiretroviral treatment (ART), an externally initiated biomedical intervention, is being rolled out across sub-Saharan Africa. Understanding the ways in which community networks are working to facilitate optimal ART access and adherence will enable policymakers to better engage with and bolster these pre-existing resources. We conducted 67 interviews and eight focus group discussions with 127 people from three key population groups in Manicaland, eastern Zimbabwe: healthcare workers, adults on ART and carers of children on ART. We also observed over 100 h of HIV treatment sites at local clinics and hospitals. Our research sought to determine how indigenous resources were enabling people to achieve optimal ART access and adherence. We analysed data transcripts using thematic network technique, coding references to supportive community networks that enable local people to achieve ART access and adherence. People on ART or carers of children on ART in Zimbabwe report drawing support from a variety of social networks that enable them to overcome many obstacles to adherence. Key support networks include: HIV groups; food and income support networks; home-based care, church and women's groups; family networks; and relationships with healthcare providers. More attention to the community context in which HIV initiatives occur will help ensure that interventions work with and benefit from pre-existing social capital.


Assuntos
Antirretrovirais/uso terapêutico , Infecções por HIV/tratamento farmacológico , Adesão à Medicação/psicologia , Pobreza , Capital Social , Antirretrovirais/administração & dosagem , Agentes Comunitários de Saúde/organização & administração , Feminino , Educação em Saúde/organização & administração , Promoção da Saúde/organização & administração , Acesso aos Serviços de Saúde , Serviços de Assistência Domiciliar/organização & administração , Humanos , Entrevistas como Assunto , Masculino , Relações Profissional-Paciente , Religião , Grupos de Autoajuda , Estigma Social , Apoio Social , Zimbábue
4.
AIDS Care ; 25 Suppl 1: S88-96, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23745635

RESUMO

Membership of indigenous local community groups was protective against HIV for women, but not for men, in eastern Zimbabwe during the period of greatest risk reduction (1999-2004). We use four rounds of data from a population cohort to investigate: (1) the effects of membership of multiple community groups during this period; (2) the effects of group membership in the following five years; and (3) the effects of characteristics of groups hypothesised to determine their effect on HIV risk. HIV incidence from 1998 to 2003 was 1.18% (95% CI: 0.78-1.79%), 0.48% (0.20-1.16%) and 1.13% (0.57-2.27%), in women participating in one, two and three or more community groups at baseline versus 2.19% (1.75-2.75%) in other women. In 2003-2005, 36.5% (versus 43% in 1998-2000) of women were members of community groups, 50% and 56% of which discussed HIV prevention and met with other groups, respectively; the corresponding figures for men were 24% (versus 28% in 1998-2000), 51% and 58%. From 2003 to 2008, prior membership of community groups was no longer protective against HIV for women (1.13% versus 1.29%, aIRR = 1.25; p = 0.23). However, membership of groups that provided social spaces for dialogue about HIV prevention (0.62% versus 1.01%, aIRR = 0.54; p = 0.28) and groups that interacted with other groups (0.65% versus 1.01%, aIRR = 0.51; p = 0.19) showed non-significant protective effects. For women, membership of a group with external sponsorship showed a non-significant increase in HIV risk compared to membership of unsponsored groups (adjusted odds ratio = 1.63, p = 0.48). Between 2003 and 2008, membership of community groups showed a non-significant tendency towards higher HIV risk for men (1.47% versus 0.94%, p = 0.23). Community responses contributed to HIV decline in eastern Zimbabwe. Sensitive engagement and support for local groups (including non-AIDS groups) to encourage dialogue on positive local responses to HIV and to challenge harmful social norms and incorrect information could enhance HIV prevention.


Assuntos
Redes Comunitárias/estatística & dados numéricos , Participação da Comunidade/tendências , Infecções por HIV/prevenção & controle , Comportamento Sexual , Adulto , Redes Comunitárias/organização & administração , Pesquisa Participativa Baseada na Comunidade , Feminino , Infecções por HIV/epidemiologia , Humanos , Incidência , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Organizações sem Fins Lucrativos , Distribuição de Poisson , Estudos Prospectivos , Comportamento de Redução do Risco , Fatores de Tempo , Adulto Jovem , Zimbábue/epidemiologia
5.
Eur Phys J C Part Fields ; 73(5): 2431, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-25814859

RESUMO

The LHCb experiment has been taking data at the Large Hadron Collider (LHC) at CERN since the end of 2009. One of its key detector components is the Ring-Imaging Cherenkov (RICH) system. This provides charged particle identification over a wide momentum range, from 2-100 GeV/c. The operation and control, software, and online monitoring of the RICH system are described. The particle identification performance is presented, as measured using data from the LHC. Excellent separation of hadronic particle types (π, K, p) is achieved.

6.
Child Care Health Dev ; 38(5): 732-42, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21985490

RESUMO

OBJECTIVE: We use children's drawings to investigate social stigmatization of AIDS-affected and poverty-affected children by their peers, in the light of suggestions that the stigmatization of AIDS-affected children might derive more from the poverty experienced by these children than from their association with AIDS. METHODS: A qualitative study, in rural Zimbabwe, used draw-and-write techniques to elicit children's (10-12 years) representations of AIDS-affected children (n= 30) and poverty-affected children (n= 33) in 2009 and 2010 respectively. RESULTS: Representations of children affected by AIDS and by poverty differed significantly. The main problems facing AIDS-affected children were said to be the psychosocial humiliations of AIDS stigma and children's distress about sick relatives. Contrastingly, poverty-affected children were depicted as suffering from physical and material neglect and deprivation. Children affected by AIDS were described as caregivers of parents whom illness prevented from working. This translated into admiration and respect for children's active contribution to household survival. Poverty-affected children were often portrayed as more passive victims of their guardians' inability or unwillingness to work or to prioritize their children's needs, with these children having fewer opportunities to exercise agency in response to their plight. CONCLUSIONS: The nature of children's stigmatization of their AIDS-affected peers may often be quite distinct from poverty stigma, in relation to the nature of suffering (primarily psychosocial and material respectively), the opportunities for agency offered by each affliction, and the opportunities each condition offers for affected children to earn the respect of their peers and community. We conclude that the particular nature of AIDS stigma offers greater opportunities for stigma reduction than poverty stigma.


Assuntos
Síndrome de Imunodeficiência Adquirida/psicologia , Pobreza , Estigma Social , Atividades Cotidianas , Arte , Atitude Frente a Saúde , Criança , Emoções , Feminino , Trabalho Doméstico , Humanos , Masculino , Papel (figurativo) , Saúde da População Rural , Responsabilidade Social , Apoio Social , Saúde da População Urbana , Zimbábue
7.
Sex Transm Infect ; 87(7): 621-8, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21636615

RESUMO

OBJECTIVES: To develop projections of the resources required (person-years of drug supply and healthcare worker time) for universal access to antiretroviral treatment (ART) in Zimbabwe. METHODS: A stochastic mathematical model of disease progression, diagnosis, clinical monitoring and survival in HIV infected individuals. FINDINGS: The number of patients receiving ART is determined by many factors, including the strategy of the ART programme (method of initiation, frequency of patient monitoring, ability to include patients diagnosed before ART became available), other healthcare services (referral rates from antenatal clinics, uptake of HIV testing), demographic and epidemiological conditions (past and future trends in incidence rates and population growth) as well as the medical impact of ART (average survival and the relationship with CD4 count when initiated). The variations in these factors lead to substantial differences in long-term projections; with universal access by 2010 and no further prevention interventions, between 370 000 and almost 2 million patients could be receiving treatment in 2030-a fivefold difference. Under universal access, by 2010 each doctor will initiate ART for up to two patients every day and the case-load for nurses will at least triple as more patients enter care and start treatment. CONCLUSIONS: The resources required by ART programmes are great and depend on the healthcare systems and the demographic/epidemiological context. This leads to considerable uncertainty in long-term projections and large variation in the resources required in different countries and over time. Understanding how current practices relate to future resource requirements can help optimise ART programmes and inform long-term public health planning.


Assuntos
Fármacos Anti-HIV/administração & dosagem , Fármacos Anti-HIV/economia , Infecções por HIV/diagnóstico , Infecções por HIV/tratamento farmacológico , Instalações de Saúde , Recursos em Saúde/estatística & dados numéricos , Acesso aos Serviços de Saúde/economia , Infecções por HIV/epidemiologia , Humanos , Modelos Teóricos , Análise de Sobrevida , Recursos Humanos , Zimbábue/epidemiologia
8.
AIDS Care ; 23(8): 957-64, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21400306

RESUMO

Grandparents throughout sub-Saharan Africa have shown immense courage and fortitude in providing care and support for AIDS-affected children. However, growing old comes with a number of challenges which can compromise the quality of care and support they are able to provide, particularly for children infected by HIV and enrolled on antiretroviral therapy (ART) programmes. For ART to be effective, and for infected children not to develop drug-resistance, a complex treatment regimen must be followed. Drawing on the perspectives of 25 nurses and eight grandparents of HIV-infected children in Manicaland, eastern Zimbabwe, we explore some of the challenges faced by grandparents in sustaining children's adherence to ART. These challenges, serving as barriers to paediatric ART, are poverty, immobility, deteriorating memory and poor comprehension of complex treatments. Although older HIV-infected children were found to play an active role in sustaining the adherence to their programme of treatment by contributing to income and food generating activities and reminding their guardians about check-ups and drug administration, such contribution was not available from younger children. There is therefore an urgent need to develop ART services that both take into consideration the needs of elderly guardians and acknowledge and enhance the agency of older children as active and responsible contributors to ART adherence.


Assuntos
Antirretrovirais/uso terapêutico , Cuidadores/psicologia , Infecções por HIV/tratamento farmacológico , Infecções por HIV/psicologia , Adesão à Medicação/psicologia , África Subsaariana , Fatores Etários , Idoso , Cuidadores/educação , Criança , Proteção da Criança , Pré-Escolar , Feminino , Acesso aos Serviços de Saúde , Humanos , Lactente , Relação entre Gerações , Masculino , Pessoa de Meia-Idade , Pobreza , Apoio Social , Zimbábue
9.
AIDS Care ; 23(7): 797-802, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21400319

RESUMO

The roll-out of accessible and affordable antiretroviral (ARV) drugs for people living with HIV in low-income countries is drastically changing the nature of HIV-related healthcare. The Zimbabwean Ministry of Health has renewed efforts to make antiretroviral treatment (ART) for HIV free and publically available across the country. This paper describes the findings from a multi-method qualitative study including interviews and a focus group with healthcare workers (mostly nurses), totalling 25 participants, and field notes from over 100 hours of ethnographic observation in three rural Zimbabwean health centres. These health centres began providing free ARV drugs to HIV-positive people over one year prior to the research period. We examined sources of motivation and frustration among nurses administering ART in these resource-poor health centres. The findings suggest that healthcare workers administering ART in challenging circumstances are adept at drawing strength from the dramatic physical and emotional recoveries made possible by ART and from their personal memories of the suffering caused by HIV/AIDS among close friends or family. However, healthcare staff grappled with extreme resource shortages, which led to exhaustion and frustration. Surprisingly, only one year into ART provision, healthcare workers did not reference the professional challenges of their HIV work before ART became available, suggesting that medical breakthroughs such as ART rapidly come to be seen as a standard element of nursing. Our findings provide a basis for optimism that medical breakthroughs such as ART can reinvigorate healthcare workers in the short term. However, we caution that the daily challenges of nursing in poor environments, especially administering an ongoing and resource-intensive regime such as ART, must be addressed to enable nurses to continue delivering high-quality ART in sub-Saharan Africa.


Assuntos
Fármacos Anti-HIV/uso terapêutico , Infecções por HIV/tratamento farmacológico , Pessoal de Saúde/psicologia , Grupos Focais , Frustração , Infecções por HIV/enfermagem , Acesso aos Serviços de Saúde , Necessidades e Demandas de Serviços de Saúde , Humanos , Motivação , Pesquisa Qualitativa , Saúde da População Rural , Zimbábue
10.
AIDS Care ; 22(8): 988-96, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20552465

RESUMO

Substantial resources are invested in psychological support for children orphaned or otherwise made vulnerable in the context of HIV/AIDS (OVC). However, there is still only limited scientific evidence for greater psychological distress amongst orphans and even less evidence for the effectiveness of current support strategies. Furthermore, programmes that address established mechanisms through which orphanhood can lead to greater psychological distress should be more effective. We use quantitative and qualitative data from Eastern Zimbabwe to measure the effects of orphanhood on psychological distress and to test mechanisms for greater distress amongst orphans suggested in a recently published theoretical framework. Orphans were found to suffer greater psychological distress than non-orphans (sex- and age-adjusted co-efficient: 0.15; 95% CI 0.03-0.26; P=0.013). Effects of orphanhood contributing to their increased levels of distress included trauma, being out-of-school, being cared for by a non-parent, inadequate care, child labour, physical abuse, and stigma and discrimination. Increased mobility and separation from siblings did not contribute to greater psychological distress in this study. Over 40% of orphaned children in the sample lived in households receiving external assistance. However, receipt of assistance was not associated with reduced psychological distress. These findings and the ideas put forward by children and caregivers in the focus group discussions suggest that community-based programmes that aim to improve caregiver selection, increase support for caregivers, and provide training in parenting responsibilities and skills might help to reduce psychological distress. These programmes should be under-pinned by further efforts to reduce poverty, increase school attendance and support out-of-school youth.


Assuntos
Crianças Órfãs/psicologia , Infecções por HIV/psicologia , Estresse Psicológico/psicologia , Adolescente , Criança , Pré-Escolar , Feminino , Infecções por HIV/epidemiologia , Infecções por HIV/mortalidade , Humanos , Lactente , Masculino , Modelos Psicológicos , Fatores Socioeconômicos , Estresse Psicológico/etiologia , Zimbábue/epidemiologia
11.
J Epidemiol Community Health ; 64(4): 330-4, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19854751

RESUMO

BACKGROUND: Verbal autopsy is currently the only option for obtaining cause of death information in most populations with a widespread HIV/AIDS epidemic. METHODS: With the use of a data-driven algorithm, a set of criteria for classifying AIDS mortality was trained. Data from two longitudinal community studies in Tanzania and Zimbabwe were used, both of which have collected information on the HIV status of the population over a prolonged period and maintained a demographic surveillance system that collects information on cause of death through verbal autopsy. The algorithm was then tested in different times (two phases of the Zimbabwe study) and different places (Tanzania and Zimbabwe). RESULTS: The trained algorithm, including nine signs and symptoms, performed consistently based on sensitivity and specificity on verbal autopsy data for deaths in 15-44-year-olds from Zimbabwe phase I (sensitivity 79%; specificity 79%), phase II (sensitivity 83%; specificity 75%) and Tanzania (sensitivity 75%; specificity 74%) studies. The sensitivity dropped markedly for classifying deaths in 45-59-year-olds. CONCLUSIONS: Verbal autopsy can consistently measure AIDS mortality with a set of nine criteria. Surveillance should focus on deaths that occur in the 15-44-year age group for which the method performs reliably. Addition of a handful of questions related to opportunistic infections would enable other widely used verbal autopsy tools to apply this validated method in areas for which HIV testing and hospital records are unavailable or incomplete.


Assuntos
Síndrome de Imunodeficiência Adquirida/mortalidade , Algoritmos , Autopsia/estatística & dados numéricos , Adolescente , Adulto , Distribuição por Idade , Autopsia/métodos , Causas de Morte , Humanos , Estudos Longitudinais , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Tanzânia/epidemiologia , Adulto Jovem , Zimbábue/epidemiologia
12.
Sex Transm Infect ; 85 Suppl 1: i34-40, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19307339

RESUMO

OBJECTIVE: To identify reporting biases and to determine the influence of inconsistent reporting on observed trends in the timing of age at first sex and age at marriage. METHODS: Longitudinal data from three rounds of a population-based cohort in eastern Zimbabwe were analysed. Reports of age at first sex and age at marriage from 6837 individuals attending multiple rounds were classified according to consistency. Survival analysis was used to identify trends in the timing of first sex and marriage. RESULTS: In this population, women initiate sex and enter marriage at younger ages than men but spend much less time between first sex and marriage. Among those surveyed between 1998 and 2005, median ages at first sex and first marriage were 18.5 years and 21.4 years for men and 18.2 years and 18.5 years, respectively, for women aged 15-54 years. High levels of reports of both age at first sex and age at marriage among those attending multiple surveys were found to be unreliable. Excluding reports identified as unreliable from these analyses did not alter the observed trends in either age at first sex or age at marriage. Tracing birth cohorts as they aged revealed reporting biases, particularly among the youngest cohorts. Comparisons by birth cohorts, which span a period of >40 years, indicate that median age at first sex has remained constant over time for women but has declined gradually for men. CONCLUSIONS: Although many reports of age at first sex and age at marriage were found to be unreliable, inclusion of such reports did not result in artificial generation or suppression of trends.


Assuntos
Coito/psicologia , Infecções por HIV/epidemiologia , Casamento/psicologia , Adolescente , Adulto , Fatores Etários , Estudos de Coortes , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Casamento/estatística & dados numéricos , Pessoa de Meia-Idade , Fatores de Risco , Saúde da População Rural , Fatores Sexuais , Adulto Jovem , Zimbábue/epidemiologia
13.
Sex Transm Infect ; 85 Suppl 1: i41-8, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19307340

RESUMO

BACKGROUND: AIDS is the main driver of young widowhood in southern Africa. METHODS: The demographic characteristics of widows, their reported risk behaviours and the prevalence of HIV were examined by analysing a longitudinal population-based cohort of men and women aged 15-54 years in Manicaland, eastern Zimbabwe. The results from statistical analyses were used to construct a mathematical simulation model with the aim of estimating the contribution of widow behaviour to heterosexual HIV transmission. RESULTS: 413 (11.4%) sexually experienced women and 31 (1.2%) sexually experienced men were reported to be widowed at the time of follow-up. The prevalence of HIV was exceptionally high among both widows (61%) and widowers (male widows) (54%). Widows were more likely to have high rates of partner change and engage in a pattern of transactional sex than married women. Widowers took partners who were a median of 10 years younger than themselves. Mathematical model simulations of different scenarios of sexual behaviour of widows suggested that the sexual activity of widow(er)s may underlie 8-17% of new HIV infections over a 20-year period. CONCLUSIONS: This combined statistical analysis and model simulation suggest that widowhood plays an important role in the transmission of HIV in this rural Zimbabwean population. High-risk partnerships may be formed when widowed men and women reconnect to the sexual network.


Assuntos
Infecções por HIV/transmissão , Heterossexualidade/estatística & dados numéricos , Viuvez/estatística & dados numéricos , Adolescente , Adulto , Feminino , Infecções por HIV/epidemiologia , Humanos , Incidência , Pessoa de Meia-Idade , Prevalência , Saúde da População Rural , Sexo sem Proteção/estatística & dados numéricos , Adulto Jovem , Zimbábue/epidemiologia
14.
Epidemics ; 1(2): 77-82, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21352753

RESUMO

OBJECTIVE: HIV Testing and Counselling (TC) programmes are being scaled-up as part of efforts to provide universal access to antiretroviral treatment (ART). METHODS AND FINDINGS: Mathematical modelling of TC in Zimbabwe shows that if universal access is to be sustained, TC must include prevention counselling that enables behaviour change among infected and uninfected individuals. The predicted impact TC is modest, but improved programmes could generate substantial reductions in incidence, reducing need for ART in the long-term. CONCLUSIONS: TC programmes that focus only on identifying those in need of treatment will not be sufficient to bring the epidemic under control.


Assuntos
Aconselhamento , Infecções por HIV/prevenção & controle , Infecções por HIV/psicologia , Comportamentos Relacionados com a Saúde , Adolescente , Adulto , Antirretrovirais/uso terapêutico , Simulação por Computador , Feminino , Infecções por HIV/diagnóstico , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , Acesso aos Serviços de Saúde , Humanos , Masculino , Metanálise como Assunto , Psicometria , Comportamento Sexual/etnologia , Adulto Jovem , Zimbábue/epidemiologia
15.
Sex Transm Infect ; 84 Suppl 1: i57-i62, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18647868

RESUMO

OBJECTIVES: Model-based estimates of maternal (but not paternal) orphanhood are higher than those based on data from demographic and health surveys (DHS). We investigate the consistency of reporting of parental survival status in data from Manicaland, Zimbabwe. METHODS: We compared estimates of paternal and maternal orphan prevalence in three rounds of a prospective household census in Manicaland (1998-2005) with estimates from DHS surveys and UNAIDS model projections. We investigated the consistency of reporting of parental survival status across the three rounds and compared estimates of adult mortality from the orphan data with direct estimates from concurrent follow-up of a general population cohort. Qualitative data were collected on possible reasons for misreporting. RESULTS: Paternal and maternal orphan prevalence is increasing in Zimbabwe. Mothers reported as deceased in round 1 of the Manicaland survey were more likely than fathers to be reported as alive in rounds 2 or 3 (33.3% vs 13.4%). This pattern was most apparent among younger children. The qualitative findings suggest that foster parents sometimes claim adopted children as their natural children. CONCLUSIONS: These results are consistent with misreporting of foster parents as natural parents. This appears to be particularly common among foster mothers and could partly explain the discrepancy between mathematical model and DHS estimates of maternal orphanhood.


Assuntos
Crianças Órfãs/estatística & dados numéricos , Pai/estatística & dados numéricos , Infecções por HIV/mortalidade , Mães/estatística & dados numéricos , Adolescente , Criança , Pré-Escolar , Coleta de Dados/métodos , Métodos Epidemiológicos , Feminino , Cuidados no Lar de Adoção/estatística & dados numéricos , Humanos , Lactente , Recém-Nascido , Masculino , Prevalência , Fatores Socioeconômicos , Nações Unidas , Zimbábue/epidemiologia
16.
Int J Epidemiol ; 37(1): 77-87, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18096590

RESUMO

BACKGROUND: Complicated HIV transmission dynamics make it unclear how to design and interpret results from community-randomized controlled trials (CRCT) of interventions to prevent infection. METHODS: Mathematical modelling was used to investigate the effectiveness of interventions to prevent HIV transmission aimed at high-risk groups and factors related to the chance of recording a statistically significant result. RESULTS: Behaviour change by high-risk groups can substantially reduce HIV incidence in the whole population, although its effect is sensitive to the structure of the sexual network and the phase of the epidemic. There is a delay between the behaviour change happening and its full effect being realized in the low-risk group and this can pull the measured incidence rate ratio towards one and reduce the chance of recording a statistically significant result in a CRCT. Our simulations suggest that only with unrealistically favourable study conditions would a statistically significant result be likely with 5 years follow-up or less. Small differences in the epidemiological parameters between communities can lead to misleading incidence rate ratios. Behaviour change independent of the intervention can increase the epidemiological impact of the intervention and the chance of recording a statistically significant result. CONCLUSIONS: HIV prevention interventions, especially those targeted at high-risk groups may take longer to work at the population level and need more follow-up time in a CRCT to generate statistically significant results. Mathematical modelling can be used in the design and analysis of CRCTs to understand how the impact of the intervention could develop and the implications this has for statistical power.


Assuntos
Infecções por HIV/epidemiologia , Infecções por HIV/prevenção & controle , Educação em Saúde/organização & administração , Modelos Teóricos , Prevenção Primária/organização & administração , Avaliação de Programas e Projetos de Saúde/métodos , Ensaios Clínicos Controlados Aleatórios como Assunto , Países em Desenvolvimento , Transmissão de Doença Infecciosa/prevenção & controle , Feminino , Infecções por HIV/transmissão , Humanos , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Masculino , Prevalência , Assunção de Riscos , Sensibilidade e Especificidade , Distribuição por Sexo , Infecções Sexualmente Transmissíveis/epidemiologia , Infecções Sexualmente Transmissíveis/prevenção & controle , Zimbábue/epidemiologia
17.
Sex Transm Infect ; 83 Suppl 1: i50-54, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17314125

RESUMO

BACKGROUND: Sexual behavioural change is essential to prevent HIV infections in Africa and statistical analysis of risk factors at the individual-level may be used to design interventions. The importance of reducing cross-generational sex (young women having sex with older men) and delaying age at first sex on the spread of HIV at the population-level has been presumed but not scientifically investigated and quantified. METHODS: A mathematical model of heterosexual spread of HIV was developed to predict the population-level impact of reducing cross-generational sex and delaying sexual debut. RESULTS: The impact of behaviour change on the spread of HIV is sensitive to the structure and reaction of the sexual network. Reducing cross-generational sex could have little impact on the risk of infection unless it is accompanied by a reduction in the number of risky sexual contacts. Even peer-to-peer sexual mixing can support high endemic levels of HIV. The benefit of delaying sexual debut is comparatively small and is reduced if males continue to prefer young partners or if young women spend more time unmarried. In Manicaland, Zimbabwe, if older men were to use condoms as frequently as young men, the reduction in risk of infection could exceed that generated by a two-year delay in first sex. CONCLUSIONS: At the individual-level avoiding sex with older partners and delaying sexual debut can decrease the risk of infection but at the population-level these interventions may do little to limit the spread of HIV without wider-ranging behavioural changes throughout the sexual network.


Assuntos
Surtos de Doenças/prevenção & controle , Infecções por HIV , Comportamento Sexual , Parceiros Sexuais , Adolescente , Adulto , Fatores Etários , Idade de Início , Preservativos/estatística & dados numéricos , Feminino , Infecções por HIV/prevenção & controle , Infecções por HIV/transmissão , Humanos , Masculino , Modelos Teóricos , Fatores de Risco , Sexo sem Proteção/prevenção & controle , Zimbábue/epidemiologia
18.
Sex Transm Infect ; 82 Suppl 1: i1-8, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16581753

RESUMO

OBJECTIVE: To determine whether observed changes in HIV prevalence in countries with generalised HIV epidemics are associated with changes in sexual risk behaviour. METHODS: A mathematical model was developed to explore the relation between prevalence recorded at antenatal clinics (ANCs) and the pattern of incidence of infection throughout the population. To create a null model a range of assumptions about sexual behaviour, natural history of infection, and sampling biases in ANC populations were explored to determine which factors maximised declines in prevalence in the absence of behaviour change. Modelled prevalence, where possible based on locally collected behavioural data, was compared with the observed prevalence data in urban Haiti, urban Kenya, urban Cote d'Ivoire, Malawi, Zimbabwe, Rwanda, Uganda, and urban Ethiopia. RESULTS: Recent downturns in prevalence observed in urban Kenya, Zimbabwe, and urban Haiti, like Uganda before them, could only be replicated in the model through reductions in risk associated with changes in behaviour. In contrast, prevalence trends in urban Cote d'Ivoire, Malawi, urban Ethiopia, and Rwanda show no signs of changed sexual behaviour. CONCLUSIONS: Changes in patterns of HIV prevalence in urban Kenya, Zimbabwe, and urban Haiti are quite recent and caution is required because of doubts over the accuracy and representativeness of these estimates. Nonetheless, the observed changes are consistent with behaviour change and not the natural course of the HIV epidemic.


Assuntos
Surtos de Doenças/estatística & dados numéricos , Infecções por HIV/epidemiologia , Comportamento Sexual/psicologia , Adolescente , Adulto , Feminino , Infecções por HIV/psicologia , Haiti/epidemiologia , Heterossexualidade , Humanos , Quênia/epidemiologia , Masculino , Prevalência , Comportamento de Redução do Risco , Distribuição por Sexo , Comportamento Sexual/estatística & dados numéricos , Uganda/epidemiologia , Saúde da População Urbana , Zimbábue/epidemiologia
19.
Sex Transm Infect ; 82 Suppl 1: i42-7, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16581759

RESUMO

BACKGROUND: This paper brings together data from a variety of reports to provide a basis for assessing future steps for responding to and monitoring the HIV epidemic in Zimbabwe. METHOD: Data reported from four antenatal clinic (ANC) surveys conducted between 2000 and 2004, two small local studies in Zimbabwe conducted from 1997 through 2003, four general population surveys from 1999 through 2003, and service statistics covering 1990 through 2004 were used to describe recent trends in HIV prevalence and incidence, behaviour change, and programme provision. RESULTS: HIV prevalence among pregnant women attending ANCs declined substantially from 32.1% in 2000 to 23.9% in 2004. The local studies confirmed the decline in prevalence. However, prevalence continued to be high. Sexual behaviour data from surveys suggests a reduction in sexual experience before age 15 years among both males and females age 15-19 years, and in the proportions of males and females aged 15-29 years reporting non-regular sexual partners in the past 12 months. Reported condom use with non-regular partners has been high since 1999. Condom distribution and HIV counseling and testing increased from 2000 to 2004. DISCUSSION: On the basis of examination of data from a variety of sources, the recent decrease in HIV prevalence may be related to recent reductions in early-age sexual activity and non-regular sexual partnerships and increases in condom use. Comparison of data from sentinel surveillance systems, population based serosurveys, local studies, and service statistics provide increased confidence that a decline in HIV prevalence in Zimbabwe is actually happening in the population.


Assuntos
Infecções por HIV/epidemiologia , Complicações Infecciosas na Gravidez/epidemiologia , Adolescente , Adulto , Preservativos/estatística & dados numéricos , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Gravidez , Cuidado Pré-Natal , Prevalência , Vigilância de Evento Sentinela , Abstinência Sexual , Comportamento Sexual/estatística & dados numéricos , Zimbábue/epidemiologia
20.
Sex Transm Infect ; 82 Suppl 1: i48-51, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16581760

RESUMO

Identification of causes of changes in prevalence and incidence of HIV at a national level is important for planning future prevention and intervention needs. However, the slow progression to disease and the sensitive and stigmatising nature of the associated behaviours can make this difficult. Changing rates of incidence are to be expected as an epidemic progresses, but separating background changes from those brought about by changes in behaviour and interventions requires careful analysis. This paper discusses the criteria required to determine whether observed changes in HIV prevalence are the result of changes in behaviour.


Assuntos
Surtos de Doenças/estatística & dados numéricos , Infecções por HIV/epidemiologia , Adulto , Distribuição por Idade , Feminino , Promoção da Saúde , Humanos , Incidência , Masculino , Prevalência , Fatores de Risco , Assunção de Riscos , Vigilância de Evento Sentinela , Distribuição por Sexo , Comportamento Sexual/psicologia , Comportamento Sexual/estatística & dados numéricos , Fatores de Tempo
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