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Background:The approach to national and global estimates of HIV/AIDS used by UNAIDS starts with estimates of adult HIV prevalence prepared from surveillance data using either the Estimation and Projection Package (EPP) or the Workbook. Time trends of prevalence are transferred to Spectrum to estimate the consequences of the HIV/AIDS epidemic, including the number of people living with HIV, new infections, AIDS deaths, AIDS orphans, treatment needs and the impact of treatment on survival.Methods:The UNAIDS Reference Group on Estimates, Modelling and Projections regularly reviews new data and information needs and recommends updates to the methodology and assumptions used in Spectrum. The latest update to Spectrum was used in the 2007 round of global estimates.Results:Several new features have been added to Spectrum in the past two years. The structure of the population was reorganised to track populations by HIV status and treatment status. Mortality estimates were improved by the adoption of new approaches to estimating non-AIDS mortality by single age, and the use of new information on survival with HIV in non-treated cohorts and on the survival of patients on antiretroviral treatment (ART). A more detailed treatment of mother-to-child transmission of HIV now provides more prophylaxis and infant feeding options. New procedures were implemented to estimate the uncertainty around each of the key outputs.Conclusions: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.

BackgroundThe number of HIV-positive pregnant women receiving antiretroviral drugs (ARVs) to prevent mother-to-child transmission (MTCT) of HIV has increased rapidly.ObjectiveTo estimate the reduction in new child HIV infections resulting from prevention of MTCT (PMTCT) over the past decade. To project the potential impact of implementing the new WHO PMTCT guidelines between 2010 and 2015 and consider the efforts required to virtually eliminate MTCT, defined as <5% transmission of HIV from mother to child, or 90% reduction of infections among young children by 2015.MethodsData from 25 countries with the largest numbers of HIV-positive pregnant women were used to create five scenarios to evaluate different PMTCT interventions. A demographic model, Spectrum, was used to estimate new child HIV infections as a measure of the impact of interventions.ResultsBetween 2000 and 2009 there was a 24% reduction in the estimated annual number of new child infections in the 25 countries, of which about one-third occurred in 2009 alone. If these countries implement the new WHO PMTCT recommendations between 2010 and 2015, and provide more effective ARV prophylaxis or treatment to 90% of HIV-positive pregnant women, 1 million new child infections could be averted by 2015. Reducing HIV incidence in reproductive age women, eliminating the current unmet need for family planning and limiting the duration of breastfeeding to 12 months (with ARV prophylaxis) could avert an additional 264 000 infections, resulting in a total reduction of 79% of annual new child infections between 2009 and 2015, approaching but still missing the goal of virtual elimination of MTCT.DiscussionTo achieve virtual elimination of new child infections PMTCT programmes must achieve high coverage of more effective ARV interventions and safer infant feeding practices. In addition, a comprehensive approach including meeting unmet family planning needs and reducing new HIV infections among reproductive age women will be required.

BackgroundThere is a significant increase in survival for HIV-infected children who have early access to diagnosis and treatment. The goal of this multi-country review was to examine when and where HIV-exposed infants and children are being diagnosed, and whether the EID service is being maximally utilized to improve health outcomes for HIV-exposed children.MethodsIn four countries across Africa and Asia existing documents and data were reviewed and key informant interviews were conducted. EID testing data was gathered from the central testing laboratories and was then complemented by health facility level data extraction which took place using a standardized and validated questionnaireResultsIn the four countries reviewed from 2006 to 2009 EID sample volumes rose dramatically to an average of >100 samples per quarter in Cambodia and Senegal, >7,000 samples per quarter in Uganda, and >2,000 samples per quarter in Namibia. Geographic coverage of sites also rapidly expanded to 525 sites in Uganda, 205 in Namibia, 48 in Senegal, and 26 in Cambodia in 2009. However, only a small proportion of testing was done at lower-level health facilities: in Uganda Health Center IIs and IIIs comprised 47% of the EID collection sites, but only 11% of the total tests, and in Namibia 15% of EID sites collected >93% of all samples. In all countries except for Namibia, more than 50% of the EID testing was done after 2 months of age. Few sites had robust referral mechanisms between EID and ART. In a sub-sample of children, we noted significant attrition of infants along the continuum of care post testing. Only 22% (Senegal), 37% (Uganda), and 38% (Cambodia) of infants testing positive by PCR were subsequently initiated onto treatment. In Namibia, which had almost universal EID coverage, more than 70% of PCR-positive infants initiated ART in 2008.ConclusionsWhile EID testing has expanded dramatically, a large proportion of PCR- positive infants are initiated on treatment. As EID services continue to scale-up, more programmatic attention and support is needed to retain HIV-exposed infants in care and ensure that those testing positive initiate treatment in a timely manner. Namibia's experience demonstrates that it is feasible for a rural, low-income country to achieve high national coverage of infant testing and treatment.

Breast-feeding substantially increases the risk of HIV-1 transmission from mother to child, and although peripartum antiretroviral therapy prophylaxis significantly decreases the risk of mother-to-child transmission around the time of delivery, this approach does not affect breast-feeding transmission. Increased maternal RNA viral load in plasma and breast milk is strongly associated with increased risk of transmission through breast-feeding, as is breast health, and it has been suggested that exclusive breast-feeding could be associated with lower rates of breast-feeding transmission than mixed feeding of both breast- and other milk or feeds. Transmission through breast-feeding can take place at any point during lactation, and the cumulative probability of acquisition of infection increases with duration of breast-feeding. HIV-1 has been detected in breast milk in cell-free and cellular compartments; infant gut mucosal surfaces are the most likely site at which transmission occurs. Innate and acquired immune factors may act most effectively in combination to prevent primary HIV-1 infection by breast milk.

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