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Sexually transmitted infections 08/2008; 84 Suppl 1:i1-4. · 2.18 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Sexually transmitted infections 08/2008; 84 Suppl 1:i57-i62. · 2.18 Impact Factor
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ABSTRACT: To quantify the proportion of people living with HIV who are being affected by emergencies.
Emergencies were defined as conflict, natural disaster and/or displacement. Country-specific estimates of populations affected by emergencies were developed based on eight publicly available databases and sources. These estimates were calculated as proportions and then combined with updated country-level HIV estimates for the years 2003, 2005 and 2006 to obtain estimates of the number of men, women and children living with HIV who were also affected by emergencies.
In 2006, 1.8 (range 1.3-2.5) million people living with HIV (PLHIV) were also affected by conflict, disaster or displacement, representing 5.4% (range 4.0-7.6%) of the global number of PLHIV. In the same year, an estimated 930 000 (range 660 000-1.3 million) women and 150 000 (range 110 000-230 000) children under 15 years living with HIV were affected by emergencies. In emergency settings, the estimated numbers of PLHIV in 2003 and 2005 were 2.6 million (range 2.0-3.4 million) and 1.7 million (range 1.4-2.1 million), respectively, representing 7.9% and 5.1% of the global number of PLHIV).
These estimates provide a rationale to ensure that HIV interventions are integrated into rapid assessment of all emergency and preparedness and response plans to prevent HIV infections and address excess suffering, morbidity and mortality among these often overlooked vulnerable groups.
Sexually transmitted infections 08/2008; 84 Suppl 1:i42-i48. · 2.18 Impact Factor
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Vulnerable Children and Youth Studies 03/2007; April 2007; Vol. 2(1: pp. 40–59):40-59.
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Sexually Transmitted Infections 07/2006; 82 Suppl 3:iii1-2. · 2.85 Impact Factor
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ABSTRACT: In the Joint United Nations Programme on HIV/AIDS (UNAIDS) approach to HIV and AIDS estimates, estimates of adult prevalence produced by the Estimation and Projection Package (EPP) or the Workbook are transferred to Spectrum to estimate the consequences of the HIV/AIDS epidemic, including the number of people living with HIV by age and sex, new infections, AIDS deaths, AIDS orphans, treatment needs, and the impact of treatment on survival.
The UNAIDS Reference Group on Estimates, Models and Projections recommends updates to the methodology and assumptions based on the latest research findings and international policy and programme guidelines. The latest update to Spectrum has been used in the 2005 round of global estimates.
Several new features have been added to Spectrum in the past two years. New patterns of the age distribution of prevalence over time are based on the latest survey data. A more detailed treatment of mother to child transmission of HIV is now based on information about current breastfeeding practices, treatment options offered to prevent mother to child transmission (PMTCT), infant feeding options, and the percentage or number of pregnant women accessing PMTCT services. A new section on child survival includes the effects of cotrimoxazole and ART on child survival. Projections can now be calibrated with national survey data. A new set of outputs is provided for all adults over the age of 15 in addition to the traditional 15-49 age group. New outputs are now available to show plausibility bounds and regional estimates for key indicators.
The latest update to the Spectrum program is intended to incorporate the latest research findings and provide new outputs needed by national and international planners.
Sexually Transmitted Infections 07/2006; 82 Suppl 3:iii45-50. · 2.85 Impact Factor
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ABSTRACT: Since 1998 the Joint United Nations Programme on HIV/AIDS and the World Health Organization has provided estimates on the magnitude of the HIV epidemic for individual countries. Starting with the 2003 estimates, plausibility bounds about the estimates were also reported. The bounds are intended to serve as a guide as to what reasonable or plausible ranges are for the uncertainty in HIV incidence, prevalence, and mortality.
Plausibility bounds were developed for three situations: for countries with generalised epidemics, for countries with low level or concentrated epidemics (LLC), and for regions. The techniques used build on those developed for the previous reporting round. However the current bounds are based on the available surveillance and survey data from each individual country rather than on data from a few prototypical countries.
The uncertainty around the HIV estimates depends on the quality of the surveillance system in the country. Countries with population based HIV seroprevalence surveys have the tightest plausibility bounds (average relative range about the adult HIV prevalence (ARR) of -18% to +19%.) Generalised epidemic countries without a survey have the next tightest ranges (average ARR of -46% to +59%). Those LLC countries which have conducted multiple surveys over time for HIV among the populations most at risk have the bounds similar to those in generalised epidemic countries (ARR -40% to +67%). As the number and quality of the studies in LLC countries goes down, the plausibility bounds increase (ARR of -38% to +102% for countries with medium quality data and ARR of -53% to +183% for countries with poor quality data). The plausibility bounds for regions directly reflect the bounds for the countries in those regions.
Although scientific, the plausibility bounds do not represent and should not be interpreted as formal statistical confidence intervals. However in order to make the bounds as meaningful as possible the authors have tried to apply reasonable statistical approaches and assumptions to their derivation. An understanding of the uncertainty in the HIV estimates may help policy makers take better informed decisions to address the epidemic in their respective countries.
Sexually Transmitted Infections 07/2006; 82 Suppl 3:iii71-77. · 2.85 Impact Factor
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T B Hallett,
J Aberle-Grasse,
G Bello,
L-M Boulos,
M P A Cayemittes,
B Cheluget,
J Chipeta,
R Dorrington,
S Dube,
A K Ekra, [......],
S Kassim,
W Kirungi,
L Kouassi,
A Mahomva,
L Marum,
C Maurice,
M Nolan,
T Rehle,
J Stover, N Walker
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ABSTRACT: To determine whether observed changes in HIV prevalence in countries with generalised HIV epidemics are associated with changes in sexual risk behaviour.
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.
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.
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.
Sexually Transmitted Infections 05/2006; 82 Suppl 1:i1-8. · 2.85 Impact Factor
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ABSTRACT: This paper describes the Estimation and Projection Package (EPP) for estimating and projecting HIV prevalence levels in countries with generalised epidemics. The paper gives an overall summary of the software and interface. It describes the process of defining and modelling a national epidemic in terms of locally relevant sub-epidemics and the four epidemiological parameters used to fit a curve to produce the prevalence trends in the epidemic. It also provides an example of using the EPP in a country with a generalised epidemic. The paper discusses the strengths and weaknesses of the software and its envisaged future developments.
Sexually Transmitted Infections 09/2004; 80 Suppl 1:i5-9. · 2.85 Impact Factor
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ABSTRACT: This paper describes an approach to making estimates and short term projections of future scenarios of HIV/AIDS in countries with low level and concentrated epidemics. This approach focuses on identifying populations which through their behaviour are at higher risk of infection with HIV or who are exposed through the risk behaviour of their sexual partners. Estimates of the size and HIV prevalence of these populations allow the total number of HIV infected people in a country or region to be estimated. Subsequently, assumptions about the possible level and timing of saturation of HIV prevalence among each population can be used to explore future scenarios of HIV prevalence. The basic structure of the software used to make estimates and projections is described. This software includes a set of consistency and audit checks to help exclude unrealistic projections. The paper also discusses the strengths and weakness to this approach to making estimates and projections of HIV/AIDS in countries with low level and concentrated epidemics.
Sexually Transmitted Infections 09/2004; 80 Suppl 1:i10-13. · 2.85 Impact Factor
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ABSTRACT: To examine the quality of HIV sero-surveillance systems in countries by 2002, as well as trends between 1995 and 2002.
The quality of countries' surveillance systems was scored for five years: 1995, 1997, 1999, 2001, and 2002. Sero-surveillance data were compiled from the US Census Bureau's HIV/AIDS Surveillance Database, the EuroHIV database, and from countries' national HIV surveillance reports that were available to WHO/UNAIDS. The quality of systems was scored according to the level of the countries' epidemic.
There has been a large variation in the quality of HIV surveillance systems across the 132 countries by type of the epidemic and over time from 1995 to 2002. Over the 1995-2002 period the number of countries with a fully implemented system decreased from 57 (43%) in 1995 to 48 (36%) in 2002. The proportion of countries with a fully implemented system was 58%, 34%, and 10% in countries with a generalised, concentrated, and low level epidemic, respectively. In the 53 countries with generalised epidemics the number of countries with a fully implemented system increased from 24 (45%) in 2001 to 31 (58%) in 2002.
Many countries still have poor functioning HIV surveillance systems and require urgent strengthening. Countries should monitor and evaluate their own HIV surveillance systems and examine whether the systems are appropriate and adequate.
Sexually Transmitted Infections 09/2004; 80 Suppl 1:i25-30. · 2.85 Impact Factor
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ABSTRACT: To establish the accuracy of the country specific estimates of HIV prevalence, incidence, and AIDS mortality published every 2 years by UNAIDS and WHO.
We review sources of error in the data used to generate national HIV/AIDS and where possible estimate their statistical properties. We use numerical and approximate analytic methods to estimate the combined impact of these errors on HIV/AIDS estimates. Heuristic rules are then derived to produce plausible bounds about these estimates for countries with different types of epidemic and different qualities of surveillance system.
Although 95% confidence intervals (CIs) can be estimated for some sources of error, the sizes of other sources of error must be based on expert judgment. We therefore produce plausible bounds about HIV/AIDS estimates rather than statistical CIs. The magnitude of these bounds depends on the stage of the epidemic and the quality and coverage of the sentinel HIV surveillance system. The bounds for adult estimates are narrower than those for children, and those for prevalence are narrower than those for new infections.
This paper presents a first attempt at a rigorous description of the errors associated with estimation of global statistics of an infectious disease. The proposed methods work well in countries with generalised epidemics (>1% adult HIV prevalence) where the quality of surveillance is good. Although methods have also been derived for countries with low level or concentrated epidemics, more data on the biases in the estimation process are required.
Sexually Transmitted Infections 08/2004; 80 Suppl 1:i31-38. · 2.85 Impact Factor
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ABSTRACT: The objective of this paper was to analyse the quality of HIV/AIDS sentinel surveillance systems in countries and the resulting quality of the data used to make estimates of HIV/AIDS prevalence and mortality.
Available data on sero-surveillance of HIV/AIDS in countries were compiled in the process of making the end of 1999 estimates of HIV/AIDS. These data came primarily from the HIV/AIDS Surveillance Database developed by the United States Census Bureau, from a database maintained by the European Centre for the Epidemiological Monitoring of AIDS and all country reports on sentinel surveillance that had been provided to World Health Organization or UNAIDS. Procedures were developed to score quality of surveillance systems based on four dimensions of quality: timeliness and frequency; appropriateness of groups; consistency of sites over time; and coverage provided by the system. In total, the surveillance systems from 167 countries were analysed.
Forty-seven of the 167 countries whose surveillance systems were rated were judged to have fully implemented sentinel surveillance systems; 51 were judged to have systems that had some or most aspects of a good HIV surveillance system in place and 69 were rated as having poorly functioning or non-existent surveillance systems.
This analysis suggests that the quality of HIV surveillance varies considerably. The majority of countries most affected by HIV/AIDS have systems that are providing sufficient sero-prevalence data for tracking the epidemic and making reasonable estimates of HIV prevalence. However, many countries have poor systems and strengthening these is an urgent priority.
AIDS 09/2001; 15(12):1545-54. · 6.24 Impact Factor
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B Schwartländer,
J Stover, N Walker,
L Bollinger,
J P Gutierrez,
W McGreevey,
M Opuni,
S Forsythe,
L Kumaranayake,
C Watts,
S Bertozzi
Science 07/2001; 292(5526):2434-6. · 31.20 Impact Factor
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ABSTRACT: The scale of the human immunodeficiency virus (HIV)/AIDS epidemic has exceeded all expectations since its identification 20 years ago. Globally, an estimated 36 million people are currently living with HIV, and some 20 million people have already died, with the worst of the epidemic centred on sub-Saharan Africa. But just as the spread of HIV has been greater than predicted, so too has been its impact on social capital, population structure and economic growth. Responding to AIDS on a scale commensurate with the epidemic is a global imperative, and the tools for an effective response are known. Nothing less than a sustained social mobilization is necessary to combat one of the most serious crises facing human development.
Nature 05/2001; 410(6831):968-73. · 36.28 Impact Factor
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ABSTRACT: As we enter the new millennium the world is still facing the challenge of responding to the AIDS pandemic. A new report from the Joint United Nations Programme on HIV/AIDS presents the latest statistics on prevalence, spread, and impact of the disease. In their Perspective, Schwartländer and his colleagues discuss the newly released statistics and the strategies needed to combat the further spread of HIV/AIDS and to reduce prevalence in the most severely affected countries.
Science 08/2000; 289(5476):64-6. · 31.20 Impact Factor
