Reducing the risk of perinatal HIV-1 transmission with zidovudine: results and implications of AIDS Clinical Trials Group protocol 076

Disparities in mother-to-child transmission in Northeast Brazil: regional failures within successful country programs

Perinatal HIV prevention has been successful in developing countries but disparities in success between rich countries and poor countries have also been observed. Access to prevention of mother-to-child transmission (PMTCT) remains a challenge in many developing countries. In 2007, the Ministry of Health launched the Plan to Reduce the Vertical Transmission of HIV and Syphilis in Brazil to address this need. A cross-sectional study of children living in families affected by HIV was conducted in Ceara State, Northeast Brazil between June 2008 and January 2009 to explore socioeconomic effects of HIV status. Proportion of children with an HIV-positive test was calculated and stratified by age to estimate the impact of PMTCT programs. Chi-square test was employed to compare those proportions. Stata™10.0 software was used for the calculation. We interviewed 437 adults who were visiting the hospital for a consultation or to pickup medication who also had a child less than 13 years of age living with them. They also provided information about other household members (n=1789). Our study showed that children infected with HIV or who live in a household with one or both parents infected with HIV or dead from AIDS live in families of low social class and educational achievement. Seroprevalence is not lower in the cohort of those children 0-2 as compared to 3-4 and 5-12 years of age. Even in Brazil, with its successful PMTCT program overall, there are great disparities among sites. Data from the sites reported here are equivalent to many poor areas in sub-Saharan Africa. This argues that global concern for targeting areas most affected by the epidemic must consider areas within some of the most prosperous countries in the world.

Twenty-five years of the AIDS epidemic in Brazil: principal epidemiological findings, 1980-2005

The Brazilian AIDS epidemic is undergoing important changes in its third decade. The present article reviews some central findings: the proportional reduction in cases related to injection drug use; the stability, in recent years, of new cases in the male homosexual/bisexual population; and the relative and absolute increment in heterosexual transmission, even though the estimates of incident rates still point to the first two categories mentioned as those most affected by the epidemic. Still should be detached the persistent increase in incidence rates among women and its stability in the younger age groups, probably the result of behavior changes (such as the consistent use among youth of condoms in sexual relations with casual partners and a reduction in cases related to injection drug use). It is well-know that HIV prevalence in the general population has stabilized at less than 1%, which characterizes Brazil as one of the countries with a concentrated epidemic. The article also emphasizes the growth of AIDS morbidity-mortality in the less favored socioeconomic strata and in women, and the stability of the mortality rate among men.

Preclinical assessment of HIV vaccines and microbicides by repeated low-dose virus challenges

BACKGROUND

Trials in macaque models play an essential role in the evaluation of biomedical interventions that aim to prevent HIV infection, such as vaccines, microbicides, and systemic chemoprophylaxis. These trials are usually conducted with very high virus challenge doses that result in infection with certainty. However, these high challenge doses do not realistically reflect the low probability of HIV transmission in humans, and thus may rule out preventive interventions that could protect against "real life" exposures. The belief that experiments involving realistically low challenge doses require large numbers of animals has so far prevented the development of alternatives to using high challenge doses.

METHODS AND FINDINGS

Using statistical power analysis, we investigate how many animals would be needed to conduct preclinical trials using low virus challenge doses. We show that experimental designs in which animals are repeatedly challenged with low doses do not require unfeasibly large numbers of animals to assess vaccine or microbicide success.

CONCLUSION

Preclinical trials using repeated low-dose challenges represent a promising alternative approach to identify potential preventive interventions.

HIV-1 fitness and macrophages

HIV-1 comprises a collection of closely related, but not identical, viruses or quasispecies. Fitness represents a selective advantage for propagation among populations of organisms competing in a particular environment and is an important characteristic of viruses because of a link between fitness and pathogenesis. Environmental differences based on the type of cell that is targeted for infection or the cell type that produces virus, impact fitness. CD4-expressing cells of lymphocyte or macrophage lineage are the principal host cells for HIV-1, although the milieu in lymphocytes is distinct from the macrophage environment from the perspective of cell half-life and activation, signal transduction and expression of coreceptors, and bioavailability of antiretroviral drugs. Multiple viral determinants, including entry via envelope glycoproteins, replication by reverse transcriptase, and virion maturation by protease activity, contribute to fitness in different cells and provide targets for current antiretroviral therapies. This review focuses on fitness of HIV-1 in macrophages and examines the impact of protease inhibitors on fitness of quasispecies and an unexplained discordance between fitness and pathogenesis.

Preventing perinatal transmission of HIV: an evidence-based update for midwives

This article presents an update on human immunodeficiency virus care in the United States, with an emphasis on care during pregnancy and strategies to prevent perinatal transmission. Common drug regimens are reviewed. Obstetric factors related to transmission, such as mode of delivery, also are discussed. Guidelines for collaboration between midwives and human immunodeficiency virus specialists are outlined.

Risk assessment

Risk assessment is the process by which clinicians screen for conditions that, if unmanaged, result in complications of pregnancy or adverse birth outcomes and for which an intervention would improve the well-being of the mother, child, and family. One of the major US health care goals is that by the year 2000, at least 90% of pregnant women will receive risk appropriate care. This article discusses the major risks to the mother and child during pregnancy, and presents tools to assess pregnancy well-being.