Breast-feeding during primary maternal human immunodeficiency virus infection and risk of transmission from mother to infant

Infant Feeding for Persons Living With and at Risk for HIV in the United States: Clinical Report

Pediatricians and pediatric health care professionals caring for infants born to people living with and at risk for HIV infection are likely to be involved in providing guidance on recommended infant feeding practices. Care team members need to be aware of the HIV transmission risk from breastfeeding and the recommendations for feeding infants with perinatal HIV exposure in the United States. The risk of HIV transmission via breastfeeding from a parent with HIV who is receiving antiretroviral treatment (ART) and is virally suppressed is estimated to be less than 1%. The American Academy of Pediatrics recommends that for people with HIV in the United States, avoidance of breastfeeding is the only infant feeding option with 0% risk of HIV transmission. However, people with HIV may express a desire to breastfeed, and pediatricians should be prepared to offer a family-centered, nonjudgmental, harm reduction approach to support people with HIV on ART with sustained viral suppression below 50 copies per mL who desire to breastfeed. Pediatric health care professionals who counsel people with HIV who are not on ART or who are on ART but without viral suppression should recommend against breastfeeding. Pediatric health care professionals should recommend HIV testing for all pregnant persons and HIV preexposure prophylaxis to pregnant or breastfeeding persons who test negative for HIV but are at high risk of HIV acquisition.

Pregnancy Among HIV-Serodiscordant Couples: Case Report of Vertical Transmission and Retrospective Case Series

BACKGROUND

HIV transmission during pregnancy and breastfeeding among serodiscordant heterosexual couples represents an ongoing barrier to the elimination of vertical transmission of HIV-1 infection in Canada.

OBJECTIVE

To report a case of vertical HIV transmission during breastfeeding and examine the prevalence of risk factors for HIV transmission in the pregnancy and postpartum periods among serodiscordant couples where the male partner is HIV positive and female partner HIV negative.

METHODS

Case report and retrospective chart review of HIV-serodiscordant pregnant couples over an eight-year period in Edmonton, Canada.

RESULTS

We report a case of maternal primary HIV infection during the postpartum period and vertical transmission to a nursing infant that went undetected until the infant presented with AIDS. We also report a series of 41 serodiscordant pregnant couples identified by our public health nurse between 2008 and 2016. Among HIV-infected male partners, 20 (49%) had a detectable viral load (VL) during their partner's pregnancy and during breastfeeding, with median peak VL 4,700 copies/mL (range 49-120,000) and 5,100 copies/mL (range 40-120,000) during pregnancy and breastfeeding, respectively. None of the female partners seroconverted during pregnancy, but three seroconverted at 1.8, 2.4, and 6.9 years after delivery. No vertical transmission occurred.

CONCLUSION

Despite concerted attempts to minimize HIV transmission during pregnancy and breastfeeding in our well-resourced setting, residual transmission risk remains due to non-suppressed viral load within many HIV-serodiscordant pregnant couples.

Timing of HIV testing among pregnant and breastfeeding women and risk of mother-to-child HIV transmission in Malawi: a sampling-based cohort study

INTRODUCTION

Pregnant women living with HIV can achieve viral suppression and prevent HIV mother-to-child transmission (MTCT) with timely HIV testing and early ART initiation and maintenance. Although it is recommended that pregnant women undergo HIV testing early in antenatal care in Malawi, many women test positive during breastfeeding because they did not have their HIV status ascertained during pregnancy, or they tested negative during pregnancy but seroconverted postpartum. We sought to estimate the association between the timing of last positive HIV test (during pregnancy vs. breastfeeding) and outcomes of maternal viral suppression and MTCT in Malawi's PMTCT programme.

METHODS

We conducted a two-stage cohort study among mother-infant pairs in 30 randomly selected high-volume health facilities across five nationally representative districts of Malawi between 1 July 2016 and 30 June 2017. Log-binomial regression was used to estimate prevalence ratios (PR) and risk ratios (RR) for associations between timing of last positive HIV test (i.e. breastfeeding vs. pregnancy) and maternal viral suppression and MTCT, controlling for confounding using inverse probability weighting.

RESULTS

Of 822 mother-infant pairs who had available information on the timing of the last positive HIV test, 102 mothers (12.4%) had their last positive test during breastfeeding. Women who lived one to two hours (PR = 2.15; 95% CI: 1.29 to 3.58) or >2 hours (PR = 2.36; 95% CI: 1.37 to 4.10) travel time to the nearest health facility were more likely to have had their last positive HIV test during breastfeeding compared to women living <1 hour travel time to the nearest health facility. The risk of unsuppressed VL did not differ between women who had their last positive HIV test during breastfeeding versus pregnancy (adjusted RR [aRR] = 0.87; 95% CI: 0.48 to 1.57). MTCT risk was higher among women who had their last positive HIV test during breastfeeding compared to women who had it during pregnancy (aRR = 6.57; 95% CI: 3.37 to 12.81).

CONCLUSIONS

MTCT in Malawi occurred disproportionately among women with a last positive HIV test during breastfeeding. Testing delayed until the postpartum period may lead to higher MTCT. To optimize maternal and child health outcomes, PMTCT programmes should focus on early ART initiation and providing targeted testing, prevention, treatment and support to breastfeeding women.

A Missed Opportunity for U.S. Perinatal Human Immunodeficiency Virus Elimination: Pre-exposure Prophylaxis During Pregnancy

OBJECTIVE

To estimate the proportion of women at increased risk of sexual human immunodeficiency virus (HIV) acquisition during pregnancy in a high HIV incidence urban setting to identify those who may be eligible for pre-exposure prophylaxis.

METHODS

We conducted a retrospective cohort study of women who received prenatal care at a large academic center in 2012. Univariable analyses and multiple logistic regression models were built to identify correlates for pre-exposure prophylaxis eligibility.

RESULTS

Among 1,637 pregnant women, mean age was 27.6 years (SD 6.3), 59.7% were African American, and 56.0% were single. Based on the Centers for Disease Control and Prevention's guidelines, more than 10% of women were at increased risk for HIV acquisition during pregnancy and eligible for pre-exposure prophylaxis. Younger [adjusted odds ratio (OR) 0.9/1-year increase, 95% CI 0.8-0.9], single (adjusted OR 2.4, 95% CI 1.2-4.8), African American women (adjusted OR 3.3, 95% CI 1.6-6.7) with higher parity (adjusted OR 1.3/one-child increase, 95% CI 1.1-1.5), and who smoked regularly during pregnancy (adjusted OR 1.8, 95% CI 1.0-3.0) had greater odds of being eligible for pre-exposure prophylaxis at any time during pregnancy.

CONCLUSIONS

Pregnancy is a vulnerable period during which some heterosexual women in urban settings have a high risk for HIV acquisition and stand to benefit from pre-exposure prophylaxis.

Outcomes of prevention of mother to child transmission of the human immunodeficiency virus-1 in rural Kenya--a cohort study

BACKGROUND

Success in prevention of mother-to-child transmission (PMTCT) raises the prospect of eliminating pediatric HIV infection. To achieve global elimination, however, strategies are needed to strengthen PMTCT interventions. This study aimed to determine PMTCT outcomes and identify challenges facing its successful implementation in a rural setting in Kenya.

METHODS

A retrospective cohort design was used. Routine demographic and clinical data for infants and mothers enrolling for PMTCT care at a rural hospital in Kenya were analysed. Cox and logistic regression were used to determine factors associated with retention and vertical transmission respectively.

RESULTS

Between 2006 and 2012, 1338 infants were enrolled and followed up for PMTCT care with earlier age of enrollment and improved retention observed over time. Mother to child transmission of HIV declined from 19.4 % in 2006 to 8.9 % in 2012 (non-parametric test for trend p = 0.024). From 2009 to 2012, enrolling for care after 6 months of age, adjusted Odds Ratio [aOR]: 23.3 [95 % confidence interval (CI): 8.3-65.4], presence of malnutrition ([aOR]: 2.3 [95 % CI: 1.1-5.2]) and lack of maternal use of highly active antiretroviral therapy (HAART) (aOR: 6.5 [95 % CI: 1.4-29.4]) was associated with increased risk of HIV infection. Infant's older age at enrollment, malnutrition and maternal HAART status, were also associated with drop out from care. Infants who were not actively followed up were more likely to drop out from care (adjusted Hazard Ratio: 6.6 [95 % CI: 2.9-14.6]).

DISCUSSION

We report a temporal increase in the proportion of infants enrolling for PMTCT care before 3 months of age, improved retention in PMTCT and a significant reduction in the proportion of infants enrolled who became HIV-infected, emphasizing the benefits of PMTCT.

CONCLUSION

A simple set of risk factors at enrollment can identify mother-infant pairs most at risk of infection or drop out for targeted intervention.

HIV transmission through breastfeeding: still possible in developed countries

We describe here the case of a 13-month-old boy who acquired HIV infection postnatally through breastfeeding in a developed country in 2012. His mother had regular pregnancy follow-up and was found to be seronegative for HIV on 2 consecutive screening tests (during pregnancy and just after delivery). However, 1 year later, diagnosis of HIV infection arose in both of them after a pediatric emergency department visit for bronchitis when unexplained hepatosplenomegaly and inflammatory syndrome were noted. The negative maternal viral load found just after delivery confirmed that the mother's seroconversion occurred postnatally, which allowed for active HIV transmission during lactation and lack of the efficient preventive measures that have implemented in Belgium for years. We discuss this uncommon but still existing mode of HIV transmission in industrialized countries and highlight the importance of implementing new targeted health education interventions in addition to constant clinicians' awareness.

Incident HIV during pregnancy and postpartum and risk of mother-to-child HIV transmission: a systematic review and meta-analysis

BACKGROUND

Women may have persistent risk of HIV acquisition during pregnancy and postpartum. Estimating risk of HIV during these periods is important to inform optimal prevention approaches. We performed a systematic review and meta-analysis to estimate maternal HIV incidence during pregnancy/postpartum and to compare mother-to-child HIV transmission (MTCT) risk among women with incident versus chronic infection.

METHODS AND FINDINGS

We searched PubMed, Embase, and AIDS-related conference abstracts between January 1, 1980, and October 31, 2013, for articles and abstracts describing HIV acquisition during pregnancy/postpartum. The inclusion criterion was studies with data on recent HIV during pregnancy/postpartum. Random effects models were constructed to pool HIV incidence rates, cumulative HIV incidence, hazard ratios (HRs), or odds ratios (ORs) summarizing the association between pregnancy/postpartum status and HIV incidence, and MTCT risk and rates. Overall, 1,176 studies met the search criteria, of which 78 met the inclusion criterion, and 47 contributed data. Using data from 19 cohorts representing 22,803 total person-years, the pooled HIV incidence rate during pregnancy/postpartum was 3.8/100 person-years (95% CI 3.0-4.6): 4.7/100 person-years during pregnancy and 2.9/100 person-years postpartum (p = 0.18). Pooled cumulative HIV incidence was significantly higher in African than non-African countries (3.6% versus 0.3%, respectively; p<0.001). Risk of HIV was not significantly higher among pregnant (HR 1.3, 95% CI 0.5-2.1) or postpartum women (HR 1.1, 95% CI 0.6-1.6) than among non-pregnant/non-postpartum women in five studies with available data. In African cohorts, MTCT risk was significantly higher among women with incident versus chronic HIV infection in the postpartum period (OR 2.9, 95% CI 2.2-3.9) or in pregnancy/postpartum periods combined (OR 2.3, 95% CI 1.2-4.4). However, the small number of studies limited power to detect associations and sources of heterogeneity.

CONCLUSIONS

Pregnancy and the postpartum period are times of persistent HIV risk, at rates similar to "high risk" cohorts. MTCT risk was elevated among women with incident infections. Detection and prevention of incident HIV in pregnancy/postpartum should be prioritized, and is critical to decrease MTCT.

Estimates of peripartum and postnatal mother-to-child transmission probabilities of HIV for use in Spectrum and other population-based models

BACKGROUND

The Global Plan Towards the Elimination of New HIV Infections among Children and Keeping Their Mothers Alive aims to reduce by 2015 the number of new infections in children, in 22 priority countries, by at least 90% from 2009 levels. Mathematical models, such as Spectrum, are used to estimate national and global trends of the number of infants infected through mother-to-child transmission (MTCT). However, other modelling exercises have also examined MTCT under different settings. MTCT probabilities applied in models to populations that are assumed to receive antiretroviral interventions need to reflect the most current risk estimates.

METHODS

The UNAIDS Reference Group on Estimates, Modelling and Projections held a consultation to review data on MTCT probabilities. Published literature, recent conferences and data from personal communications with principle investigators were reviewed. Based on available data, peripartum and postnatal transmission probabilities were estimated for different antiretroviral drug regimens and maternal CD4 levels including for women with incident infection.

RESULTS

Incident infections occurring during pregnancy are estimated to be associated with a 30% probability of MTCT; incident infections during breast feeding lead to a 28% probability of postnatal MTCT. The 2010 WHO recommended regimens (Options A or B) are estimated to be associated with a 2% peripartum transmission probability and 0.2% transmission probability per month of breast feeding. Peripartum and postnatal transmission probabilities were lowest for women who were taking antiretroviral therapy before the pregnancy namely 0.5% peripartum and 0.16% per month of breast feeding, respectively.

DISCUSSION

These updated probabilities of HIV transmission (applied to Spectrum in April 2011) will be used to estimate new child HIV infections and track progress towards the 2015 targets of the Global Plan.

Care of the HIV-exposed child--to breast feed or not?

Breast milk is the best form of nutrition for infants. However, it places infants born to HIV infected women at risk of acquiring HIV infection. Total avoidance of breastfeeding is the only way of completely avoiding HIV transmission through breast milk. However, this strategy has not proved to be viable in resource constrained nations. A high infection related mortality and morbidity, and a high prevalence of malnutrition have been observed in HIV exposed infants on replacement feeding. Exclusive breastfeeding for the first six months followed by rapid weaning has also not proved to be a good strategy, with a surge in infection related morbidity and malnutrition reported after weaning. Current evidence indicates that continued use of ARV prophylaxis to mother/infant starting during pregnancy and continued to cover the entire duration of breastfeeding offers the infant best chance of HIV free survival, combining the benefits of breast milk with safety induced by ARV prophylaxis.

The contribution of maternal HIV seroconversion during late pregnancy and breastfeeding to mother-to-child transmission of HIV

BACKGROUND

The prevention of mother-to-child transmission (PMTCT) of HIV has been focused mainly on women who are HIV positive at their first antenatal visit, but there is uncertainty regarding the contribution to overall transmission from mothers who seroconvert after their first antenatal visit and before weaning.

METHOD

A mathematical model was developed to simulate changes in mother-to-child transmission of HIV over time, in South Africa. The model allows for changes in infant feeding practices as infants age, temporal changes in the provision of antiretroviral prophylaxis and counseling on infant feeding, as well as temporal changes in maternal HIV prevalence and incidence.

RESULTS

The proportion of mother-to-child transmission (MTCT) from mothers who seroconverted after their first antenatal visit was 26% [95% confidence interval (CI): 22% to 30%] in 2008, or 15,000 of 57,000 infections. It is estimated that by 2014, total MTCT will reduce to 39,000 per annum, and transmission from mothers seroconverting after their first antenatal visit will reduce to 13,000 per annum, accounting for 34% (95% CI: 29% to 39%) of MTCT. If maternal HIV incidence during late pregnancy and breastfeeding were reduced by 50% after 2010, and HIV screening were repeated in late pregnancy and at 6-week immunization visits after 2010, the average annual number of MTCT cases over the 2010-2015 period would reduce by 28% (95% CI: 25% to 31%), from 39,000 to 28,000 per annum.

CONCLUSION

Maternal seroconversion during late pregnancy and breastfeeding contributes significantly to the pediatric HIV burden and needs greater attention in the planning of prevention of MTCT programs.

Mother to child transmission of HIV among Zimbabwean women who seroconverted postnatally: prospective cohort study

OBJECTIVES

To estimate the rates and timing of mother to infant transmission of HIV associated with breast feeding in mothers who seroconvert postnatally, and their breast milk and plasma HIV loads during and following seroconversion, compared with women who tested HIV positive at delivery.

DESIGN

Prospective cohort study.

SETTING

Urban Zimbabwe.

PARTICIPANTS

14 110 women and infants enrolled in the Zimbabwe Vitamin A for Mothers and Babies (ZVITAMBO) trial (1997-2001).

MAIN OUTCOME MEASURES

Mother to child transmission of HIV, and breast milk and maternal plasma HIV load during the postpartum period.

RESULTS

Among mothers who tested HIV positive at baseline and whose infant tested HIV negative with polymerase chain reaction (PCR) at six weeks (n=2870), breastfeeding associated transmission was responsible for an average of 8.96 infant infections per 100 child years of breast feeding (95% CI 7.92 to 10.14) and varied little over the breastfeeding period. Breastfeeding associated transmission for mothers who seroconverted postnatally (n=334) averaged 34.56 infant infections per 100 child years (95% CI 26.60 to 44.91) during the first nine months after maternal infection, declined to 9.50 (95% CI 3.07 to 29.47) during the next three months, and was zero thereafter. Among women who seroconverted postnatally and in whom the precise timing of infection was known (≤90 days between last negative and first positive test; n=51), 62% (8/13) of transmissions occurred in the first three months after maternal infection and breastfeeding associated transmission was 4.6 times higher than in mothers who tested HIV positive at baseline and whose infant tested HIV negative with PCR at six weeks. Median plasma HIV concentration in all mothers who seroconverted postnatally declined from 5.0 log(10) copies/mL at the last negative enzyme linked immunosorbent assay (ELISA) to 4.1 log(10) copies/mL at 9-12 months after infection. Breast milk HIV load in this group was 4.3 log(10) copies/mL 0-30 days after infection, but rapidly declined to 2.0 log(10) copies/mL and <1.5 log(10) copies/mL by 31-90 days and more than 90 days, respectively. Among women whose plasma sample collected soon after delivery tested negative for HIV with ELISA but positive with PCR (n=17), 75% of their infants were infected or had died by 12 months. An estimated 18.6% to 20.4% of all breastfeeding associated transmission observed in the ZVITAMBO trial occurred among mothers who seroconverted postnatally.

CONCLUSIONS

Breastfeeding associated transmission is high during primary maternal HIV infection and is mirrored by a high but transient peak in breast milk HIV load. Around two thirds of breastfeeding associated transmission by women who seroconvert postnatally may occur while the mother is still in the "window period" of an antibody based test, when she would test HIV negative using one of these tests. Trial registration Clinical trials.gov NCT00198718.

Operational effectiveness of guidelines on complete breast-feeding cessation to reduce mother-to-child transmission of HIV: results from a prospective observational cohort study at routine prevention of mother-to-child transmission sites, South Africa

OBJECTIVE

Until 2006, HIV-positive women who chose to exclusively breast-feed were advised to completely stop breast-feeding by 6 months. We investigated operational feasibility and predictors of complete breast-feeding cessation (CBC).

DESIGN

A prospective observational cohort study at 3 routine prevention of mother-to-child transmission sites, South Africa.

METHODS

Data on "complete breast-feeding cessation at 24 weeks" and "not breast-feeding (NBF) for 4 days before the last follow-up visit at or before 24 weeks" were gathered during home visits (3, 5, 7, 9, 12, 16, 20, and 24 weeks). The main subgroup of interest for this analysis was women practicing exclusive breast-feeding/predominant breast-feeding at 3 weeks. Univariate analysis, logistic regression, Kaplan-Meier Survival analysis, and Cox regression were performed.

RESULTS

Eighty-eight women (43.6%) reported CBC. "Health staff suggesting formula use: [OR(a) 4.39 (1.76-10.97)] and "infant hospitalization" [OR(a) 3.27 (1.37-7.79)] were the only significant predictors of CBC. The probability of NBF at 5, 7, 9, 12, 16, 20, and 24 weeks was 2.8% [95% confidence interval (CI) 1.8% to 3.8%], 4.3% (3.0% to 5.6%), 5.9% (4.4% to 7.4%, 9.8% (7.9% to 11.7%), 16.1 (13.8% to 18.4%), 23.1% (20.5% to 25.7%), and 37.6% (34.6% to 40.6%), respectively. Infant HIV status [hazard ratio 5.5 95% CI 2.4 to 12.5] was the only predictor of infant death. NBF was not protective against 9-month infant HIV or death in univariate and multivariable analysis.

CONCLUSIONS

At programmatic level, CBC by 24 weeks is uncommon, and success seems unrelated to predetermined social, economic, and environmental (acceptable, feasible, affordable, sustainable, and safe AFASS) criteria. Thus at this level, activities that encourage CBC (amongst women meeting AFASS criteria) need to be identified and tested.

Human milk, breastfeeding, and transmission of human immunodeficiency virus type 1 in the United States. American Academy of Pediatrics Committee on Pediatric AIDS

Transmission of human immunodeficiency virus type 1 (HIV-1) through breastfeeding has been conclusively demonstrated. The risk of such transmission has been quantified, the timing has been clarified, and certain risk factors for breastfeeding transmission have been identified. In areas where infant formula is accessible, affordable, safe, and sustainable, avoidance of breastfeeding has represented one of the main components of mother-to-child HIV-1 transmission prevention efforts for many years. In areas where affordable and safe alternatives to breastfeeding may not be available, interventions to prevent breastfeeding transmission are being investigated. Complete avoidance of breastfeeding by HIV-1-infected women has been recommended by the American Academy of Pediatrics and the Centers for Disease Control and Prevention and remains the only means by which prevention of breastfeeding transmission of HIV-1 can be absolutely ensured. This technical report summarizes the information available regarding breastfeeding transmission of HIV-1.

HIV transmission through breastfeeding: problems and prevention

The greatest burden of HIV infection in women and their children is disproportionately borne by the poorest countries, especially in sub-Saharan Africa. Breastfeeding is a major health-promoting factor for infants and children in developing countries but the risk of mother-to-child transmission (MTCT) of HIV by this route is challenging traditional practices and health policies in low-resource countries. Maternal and infant factors contributing to the risk of MTCT through breastfeeding are still poorly understood and not well researched. Factors identified include: advanced clinical stages of infection in the mother; high maternal plasma HIV-1 load; presence of mastitis; and infant oral thrush. In many developing countries, international agencies are providing support and recommendations for preventing MTCT of HIV-1 by breastfeeding. Preventive strategies supported by WHO/UNICEF and charitable agencies in some sentinel centres in sub-Saharan Africa include routine antenatal voluntary counselling and testing (VCT), PCR testing of infants of seropositive mothers at 6 weeks of age, various combinations of a shortened period (3-6 mths) of exclusive breastfeeding, perinatal administration of antiretrovirals (ARV) such as nevirapine and provision of affordable and safe infant replacement feeds (presently given free by UNICEF in some centres). Many problems, however, have hindered effective implementation of these interventions. In many poor communities, even where VCT facilities are available, acceptance of HIV testing is low because there is fear of stigmatisation by the spouse, family or community and compliance with complex drug regimens is therefore poor. Other problems include the exorbitant cost of antiretroviral drugs, inadequately resourced health care systems and unavailability or poor acceptance of safe breast-milk alternatives. The rate of mixed feeding is high and so the risk of MTCT is increased. Continued promotion of exclusive breastfeeding for at least 6 months, irrespective of HIV status, followed by a properly prepared, high energy, nutritious complementary diet, with the possibility of early weaning to an animal milk formula, still appears to be the most appropriate option for the poor in countries with high levels of MTCT not deriving any benefit from the above strategies. While a longer period of breastfeeding would probably increase the risk of MTCT in vulnerable communities, a shorter duration would certainly increase infant morbidity and mortality. Results of investigations of the efficacy of ARV for protecting the infants of HIV-infected mothers during the breastfeeding period are awaited.

Is breast not best? Feeding babies born to HIV-positive mothers: bringing balance to a complex issue

Breastfeeding prevents millions of infant deaths each year throughout the world but causes at least one-third of all pediatric HIV infections. The first randomized trial of breastfeeding versus formula feeding, reported from Nairobi in March 2000, demonstrated an improved outcome for babies of highly selected HIV-positive mothers assigned to formula feed. However, several conditions must be in place and accepted before such replacement feeding can increase HIV-free survival. The proportion of sub-Saharan African women who have access to and will accept these conditions is small. In the short term, efforts to make breastfeeding safer will probably benefit a greater number of African babies.

Use of interventions for reducing mother-to-child transmission of HIV in Australia

OBJECTIVE

To describe the extent and outcome of use of interventions for reducing the risk of HIV transmission from mother to child in Australia.

DESIGN

National surveillance for perinatal exposure to HIV.

PARTICIPANTS AND SETTING

Notified cases of HIV infection in women in Australia and their perinatally exposed children, 1982-1999.

OUTCOME MEASURES

Trends over time in use of interventions (antiretroviral therapy in pregnancy, elective caesarean delivery and avoidance of breastfeeding) and perinatally acquired HIV infection.

RESULTS

By 31 March 2000, 204 children were reported as having been born in 1982-1999 to 162 women whose HIV infection had been diagnosed by 31 December 1999. The child's HIV infection status was established for 182 (89.2%); the mother's HIV infection was diagnosed antenatally in 91 of these cases (50%). Among women diagnosed antenatally, use of elective caesarean delivery and antiretroviral therapy in pregnancy increased significantly, from 3% and 14% by women whose children were born in 1982-1993, to 21% (P=0.01) and 88% (P<0.001), respectively, by women whose children were born in 1994-1999. Most women (95%) diagnosed antenatally avoided breastfeeding their children. The percentage of infected children born to women diagnosed antenatally declined from 26% among children born in 1982-1993 to 19% among those born in 1994-1999. The percentage of infected children was significantly lower among those whose mothers used antiretroviral therapy in pregnancy (11% versus 36%; P=0.03).

CONCLUSION

Antiretroviral use in pregnancy, elective caesarean delivery and avoidance of breastfeeding have been effective interventions for reducing the risk of mother-to-child HIV transmission in Australia. While the rate of perinatal HIV transmission has declined, it remains high in comparison with rates reported from other industrialised countries.

[Breastfeeding and hepatitis C virus (HCV): the need for a careful appraisal]

We review the available data on the possible role of breast-feeding in hepatitis C virus (HCV) transmission to infants of HCV-RNA-positive mothers. Current knowledge about HCV excretion through breast milk, HCV infection of breast-fed infants by mothers contaminated after delivery, and vertical transmission risk to infants breast-fed by chronic HCV viremic mothers are presented. Vertical transmission risk by breast-feeding HCV-RNA-positive mothers is unclear: no study has been performed with the aim and the required methodology to evaluate HCV transmission risk related to breast-feeding duration. Recommendations to HCV-RNA-positive mothers who wish to breast-feed their infant are discussed in light of present knowledge about HCV secretion in breast milk, mother-to-infant HCV transmission, and historical records on vertical transmission of other viruses to infants breast-fed by their viremic mothers.

Clinical care issues for women living with HIV and AIDS in the United States

As the number of women infected with HIV in the United States continues to increase, the medical community is faced with the challenge of providing adequate and appropriate care to them. This paper reviews key questions concerning the state of knowledge on the epidemiology, biology, and clinical care of women living with HIV and AIDS in the United States. Because heterosexual transmission accounts for a growing number of cases among women, biological factors and cofactors that may enhance women's susceptibility to HIV infection are also reviewed. HIV-related gynecological issues are presented separately to evaluate whether gynecological complications are distinct in HIV-uninfected and HIV-infected women. Questions of whether there are sex-specific differences in the efficacy and adverse effects of new antiviral agents are discussed. In addition, significant gaps are highlighted that still exist in our understanding of both the effects of HIV and HIV-related drugs upon pregnancy. Finally, the psychiatric stresses and complications that affect women living with HIV and AIDS are also discussed. In each section of this review, gaps in our knowledge of these issues are identified. To properly address these disparities in knowledge, not only do efforts to gather sex-specific biomedical data need to be more exacting, but there is a distinct need to conduct more sex-specific research concerning HIV.

Risk factors for postnatal mother-child transmission of HIV-1

OBJECTIVE

To identify factors affecting HIV-1 breastfeeding transmission.

DESIGN

Longitudinal observational cohort study.

METHODS

HIV-1 seropositive pregnant women and seronegative controls were enrolled at a maternity hospital in Nairobi. Women and their children were followed from birth, and data on HIV-1 transmission, breastfeeding, clinical illness, and growth were collected. Specimens for HIV-1 serology and/or polymerase chain reaction were obtained at birth, 2, 6, and 14 weeks, 6, 9, 12, and 18 months, and every 6 months thereafter. Children were classified as HIV-1 uninfected, perinatally, or postnatally infected. Potentially breastfeeding transmission related risk factors were compared between postnatally infected and uninfected children.

RESULTS

Among children born to seropositive or seroconverting mothers, 317 were uninfected, 51 infected perinatally and 42 infected postnatally. Identified risk factors for postnatal transmission were maternal nipple lesions (OR = 2.3, CI 95% 1.1-5.0), mastitis (OR = 2.7, CI 95% 1.1-6.7), maternal CD4 cell count < 400 mm3 (OR = 4.4, CI 95% 1.9-9.9), maternal seroconversion while breastfeeding (OR = 6.0, CI 95% 1.8-19.8), infant oral thrush at < 6 months of age (OR = 2.8, CI 95% 1.3-6.2) and breastfeeding longer than 15 months (OR = 2.4, CI 95% 1.2-5.1). All factors, except maternal seroconversion due to its rarity, were independently associated with an increased postnatal transmission risk by multivariate logistic regression analysis.

CONCLUSION

In addition perinatal antiretroviral therapies, public health strategies should address: (i) prevention of maternal nipple lesions, mastitis and infant thrush; (ii) reduction of breastfeeding duration by all HIV-1-infected mothers; (iii) absolute avoidance of breastfeeding by those at high risk, and (iv) prevention of HIV-1 transmission to breastfeeding mothers.

The dilemma of postnatal mother-to-child transmission of HIV: to breastfeed or not?

The promotion of nearly universal breastfeeding has played an important role in improving child health by providing optimum nutrition and protection against common childhood infections, and by promoting child spacing. Unfortunately, it has become clear that breastfeeding is responsible also for much of the increasing burden of worldwide pediatric human immunodeficiency virus (HIV) infection, especially in the developing nations (12-14% additional risk of HIV infection transmitted by breastfeeding; 35% total proportion of all HIV-infected children in an area infected through breastfeeding). Several factors influence the transmission of HIV by breastfeeding, including whether a woman acquires her infection during breastfeeding (29% risk of transmission) or before pregnancy (7-10% risk of breastfeeding transmission),the degree of maternal plasma and breastmilk viral load, and the presence of mastitis. In areas of the world where adequate sanitary replacement feeding is not available, the decision to withhold breastfeeding so as to decrease HIV transmission may lead to increased rates of child morbidity and mortality from diarrheal and respiratory diseases, and malnutrition. This review summarizes current data on the pathophysiology of breastfeeding transmission of HIV infection, the risk factors for and incidence rates of transmission, and the feasibility of possible alternatives to exclusive breastfeeding in the setting of maternal HIV infection. Clearly, women must be fully informed about the risks of breastfeeding transmission of HIV, the risks of morbidity and mortality among nonbreastfed infants, and the expense and availability of procuring adequate replacement formula. If an uninterrupted access to a nutritionally adequate breastmilk substitute that can be safely prepared is ensured (as is possible in industrialized countries), HIV-infected women should be counseled not to breastfeed their infants.

Impact of infant feeding practices on the risk of mother to child transmission of HIV-1 in Zimbabwe

OBJECTIVE

To determine the magnitude of the contribution of infant feeding practices on the risk of mother to child transmission (MTCT) of the HIV-1 infection.

METHODOLOGY

Prospective data from birth until 24 months of age on 236 infants born to HIV-positive mothers in Harare, Zimbabwe was analysed for this study. However, because only a small proportion of infants (2.1%) were HIV-1 polymerase chain reaction (PCR) tested shortly after birth, the PCR results for infants at birth were not incorporated into our analyses. The contribution of infant feeding practices on the risk of MTCT of HIV-1 was assessed using Cox Proportional Hazards Regression Models.

RESULTS

The incidence of HIV-1 through MTCT was greatest among breastfed (8.33 per 100 child-months) and mixed fed (8.64 per 100 child-months) infants by 3 months. After adjustment for maternal age, marital status, education and infant antibody HIV-1 status, the cumulative relative risk of MTCT of HIV-1 was 4.19 (95% confidence interval (CI) 3.44, 5.09) among breastfed and 1.10 (95% CI 0.97, 1. 25) among mixed fed infants. The overall MTCT rate of HIV-1 in this study was 40.3%.

CONCLUSIONS

Breastfed infants had the greatest cumulative relative risk of MTCT of HIV-1, followed by mixed fed infants, with the highest incidences occurring within the first 3 months.

Management of HIV-infected children in the home and institutional settings. Care of children and infections control in schools, day care, hospital settings, home, foster care, and adoption

The likelihood of high-risk pediatric exposure to HIV infection, other than perinatal exposure, has been shown to be low in most cases, and HIV PEP should be considered on a case-by-case basis. Generic considerations in the management of children who have become HIV infected emphasizes the principles of inclusion, maintaining confidentiality of a child's HIV status, and notifying those who need to know about the HIV status to care properly for the child or adolescent. Although appropriate infection-control precautions are applicable for all children and for many pathogens, children especially HIV-infected children, exposed to such pathogens, must be managed in a timely fashion. In many cases, recommendations that are applicable in one setting are applicable in others. Some exceptions apply, including infection-control precautions in hospitals versus other settings. A few additional considerations have been made for special settings and activities, including adoption, foster care, athletics, summer camp, and other recreational activities.

Mother-to-child transmission of HIV-1

After reviewing the evidence on the relation of vertical transmission of HIV to stage of infection in the mother, I developed a stochastic model of transmission in which the probability of transmission per week is proportional to the virus load in the mother. The virus load in different stages of the infection is measured by viral RNA levels or tissue culture infectious virus levels in plasma. The constant of proportionality is assumed to be different for transmission during pregnancy, during parturition, and during breast-feeding. Using data on transmission from mothers who are in the primary stage of infection, I estimated the constant of proportionality and calculated the probability of transmission during pregnancy as a function of the time pregnancy starts in relation to the stage of the infection. For breast-feeding, I calculated the conditional probability of transmission by breast-feeding for 20 weeks, dependent on the infant escaping infection during pregnancy and parturition. As might be expected, the probabilities of transmission are highest if the mother is in the primary stage of infection or in late stages of the disease and is quite low when the mother is in the asymptomatic stage of the infection.

HIV in the neonate

Mother-to-infant transmission of human immunodeficiency virus (HIV) is a worldwide problem. Between 7 and 40% of infants born to HIV-positive mothers become infected. The prognosis of these infants is poor, with most developing early and rapidly progressive disease. A number of advances in diagnosis and therapy offer opportunities to reduce the rate of vertical transmission and to improve the outlook of infected infants. Antiretroviral therapy during pregnancy and the neonatal period can markedly reduce the risk of mother-to-infant transmission. Recognition that 50% or more of infections are transmitted peripartum offers scope to further reduce the rate of transmission. However there is currently no consensus on the optimal management of pregnancy in HIV-infected women, and there is an urgent need for large randomized controlled trials. The development of polymerase chain reaction and p24 antigen assays has greatly facilitated the diagnosis of neonatal HIV infection, thereby enabling earlier supportive and anti-retroviral therapy. The place of zidovudine in paediatric HIV infection is now well-established, but the future will undoubtedly bring combination anti-retroviral therapy. Optimism about the prospects for developments in the prevention and treatment of paediatric acquired immunodeficiency syndrome must be tempered by the fact that the majority of cases occur in countries where patients have little or no access to medical care.

Unnatural constituents of breast milk--medication, lifestyle, pollutants, viruses

It is well recognised that although nutritionally breast milk is the optimal food for babies, there are a number of caveats to this, based on the consequences of the modern lifestyle. Here we have considered ways in which the young breast fed child may be exposed to various environmental and medical contaminants which might cause adverse reactions and to which he/she may not otherwise be exposed. These substances are divided into four different areas: (i) medication taken by the mother; (ii) exposure to possibly addictive drugs taken by the mother; (iii) exposure to pollutants mainly from the maternal diet or as the result of her occupation; (iv) viruses. The infant who consumes breast milk may be exposed to a variety of chemicals which may have untoward effects on his/her immediate health and temperament and future development. Potentially hazardous substances ingested by the breast fed infant include medicaments (or their metabolites) that may have been ingested by the mother, potentially addictive common neurotoxicants such as nicotine, caffeine and alcohol, illicit drugs such as heroin and cocaine, and pollutants such as polychlorinated biphenyls and dichlorodiphenyltrichloroethane (DDT). There is a paucity of good information on which to base reliable estimates of the harm that this may cause the child. Although breast feeding is known to protect against bacterial infection, a number of viruses are excreted in the breast milk which may infect the child asymptomatically (e.g. cytomegalovirus, Epstein-Barr virus) and which are not known to be harmful, as well as human immunodeficiency virus (HIV) excretion which, in contrast, does appear to increase the risk of the child becoming infected. Balancing the risk of infection to the child born to an HIV infected mother, results in the proposition that known HIV positive women in developing countries (where the risk of gastrointestinal infection is high) should continue to breast feed but those in the developed world (where the risk of gastrointestinal infection is lower) are better advised to bottle feed.

Late postnatal transmission of human immunodeficiency virus type 1 infection from mothers to infants in Dar es Salaam, Tanzania

OBJECTIVE

To study late postnatal transmission of human immunodeficiency virus type 1 in a cohort of children born to HIV-1-seropositive mothers who delivered at Muhimbili Medical Centre in Dar es Salaam, Tanzania.

MATERIALS AND METHODS

Since 1991 a prospective cohort study of mother-to-child transmission of HIV-1 has been conducted at Muhimbili Medical Centre in Dar es Salaam. HIV-1-seropositive mothers and age-matched seronegative controls were recruited into the cohort at delivery together with their newborns. Diagnosis of HIV-1 infection in children was based on polymerase chain reaction, HIV-1 p24 antigen tests and HIV antibody tests. Late postnatal transmission was defined as HIV-1 infection occurring after 6 months of age in a child who was uninfected at 6 months of age and who had an HIV-1-seropositive mother. Children born to HIV-seronegative mothers were used as controls. Breast-feeding was universal in this cohort. CD4 and CD8 T lymphocytes were assayed by flow cytometry in the mothers.

RESULTS

Among 139 children born to HIV-1-seropositive mothers and known to be HIV-uninfected at 6 months of age, 8 children became HIV-1-infected at the end of their first year of life or later. No conversions were observed in children younger than 11 months. The 8 conversions were observed during a follow-up covering 1555 child months between 6 and 27 months of age corresponding to a conversion rate of 6.2 per 100 child years. Among 260 children with HIV-seronegative mothers no child became HIV-infected during the follow-up. The percentage of CD4 T lymphocytes was similar in mothers with early and late transmission but was significantly lower in transmitting than in nontransmitting mothers.

CONCLUSION

Because no HIV-1 infection occurred in children with HIV-seronegative mothers, we conclude that the observed infections at the end of the first year of life or later among children born to HIV-seropositive women were caused by late transmission from mother to child, most likely through breast-feeding.

Overshoot of HIV-1 viraemia after early discontinuation of antiretroviral treatment

OBJECTIVE

To determine whether, as predicted by predator-prey dynamics, early withdrawal of antiretroviral therapy, i.e. when the number of CD4+ lymphocytes is still elevated, results in an overshoot of HIV-1 viraemia due to infection of increased numbers of available target cells at that time.

DESIGN AND METHODS

Five HIV-1-infected individuals were identified who discontinued antiretroviral therapy for various reasons after 8-19 days, and from whom stored serum samples obtained before, during, and shortly after treatment were available for measurement of HIV-1 RNA load. A mathematical model was designed to assess whether increased target cell availability could quantitatively explain the clinical observations.

RESULTS

After therapy withdrawal, increases in the HIV-1 RNA load to levels exceeding pretreatment values by log10 0.6-1.5 copies/ml were observed after 2-17 days in all four of the individuals who had treatment-induced increases in CD4+ cell counts at the time of therapy withdrawal. Increases in viraemia were maximal within a few days, and subsequently seemed to wane until the pretreatment equilibrium between virus and its target cells was attained. Mathematical modelling confirms that these transient increases in viraemia can be explained by increased availability of target cells at the time of therapy withdrawal.

CONCLUSIONS

Transient rises in HIV-1 viraemia do occur following early therapy withdrawal. These rises especially warrant consideration in short-term antiretroviral regimens for prevention of mother-to-child transmission, as are being studied in developing countries, since they could result in an increased transmission risk during the post-partum period through breast-feeding. This possibility needs to be investigated urgently.

Breast-feeding and human immunodeficiency virus

Breast-feeding provides nutritional, immunological, and psychological benefits. It protects children from mortality and morbidity associated with diarrheal diseases, pneumonia and other infections. Breast feeding has also been shown to prolong the interval between births and thereby improve child survival and maternal health. However, studies suggest that in certain populations, breast feeding may account for nearly 14% of perinatal human immunodeficiency virus type 1 (HIV-1) transmission. It is therefore important that the risk of HIV-1 infection through breast feeding be weighed against the morbidity and mortality associated with bottle feeding. This paper discusses the literature dealing with breast feeding in women with HIV-1 infection. Specifically, the review addresses the issues surrounding infant mortality in areas of different HIV-1 prevalence where breast-feeding or bottle-feeding may be employed. Analysis suggests that the benefits of breast-feeding or bottle-feeding may be employed. Analysis suggests that the benefits of breast-feeding can substantially outweigh the putative risk of HIV-1 transmission unless the prevalence of HIV-1 infection is high or the difference in mortality between breast-fed and bottle-fed infants is very low.

Prevention of mother-to-infant transmission of HIV-1

The number of children with AIDS continues to increase worldwide. Children who become infected with HIV-1 acquire the infection almost exclusively from their mothers during pregnancy or delivery, or via breast feeding. Mother-to-infant transmission has been, and continues to be, an area of active research with the goal being complete prevention. Treatment with zidovudine, an antiviral agent, has been found to decrease transmission from 25% to 8%. However, multiple obstacles impede the worldwide application of this advance.

Late postnatal mother-to-child transmission of HIV-1 in Abidjan, Côte d'Ivoire

BACKGROUND

HIV-1 can be transmitted from an infected mother to her infant through breastfeeding, although the precise risk of transmission by this route is unknown. A long-term follow-up of children born to HIV-infected women in Abidjan, Côte d'Ivoire, has enabled us to estimate this risk.

METHODS

Children born to 138 HIV-1-seropositive women, 132 HIV-2-seropositive women, 69 women seroreactive to both HIV-1 and HIV-2, and 274 HIV-seronegative women were enrolled at birth and followed up for as long as 48 months. All children were breastfed (median duration 20 months). Blood samples for either or both HIV PCR and HIV serology were obtained at 1, 2, and 3 months of age, and every 3 months thereafter. Early HIV infection was defined as a positive HIV-1 PCR result obtained in the first 6 months of life. Late postnatal transmission was diagnosed when a child had a negative PCR at 3 or 6 months of age, followed by either or both a positive HIV-1 PCR at 9 months or older, or persistently positive HIV-1 serology at 15 months or older.

FINDINGS

82 children born to HIV-1-seropositive mothers and 57 children born to mothers seropositive for both HIV-1 and HIV-2 had PCR results for samples taken within the first 6 months. By 6 months of age, 23 (28%; 95% CI 19-39) of the 82 children born to HIV-1-seropositive mothers and ten (18%; 95% CI 9-30) of the 57 children born to dually seropositive mothers were HIV-1 infected. Among children whose PCR results were negative at or before age 6 months, and who were followed up beyond 6 months, an additional four (9%) of the 45 children born to HIV-1-seropositive mothers and two (5%) of the 39 children born to dually seropositive mothers became HIV infected. The estimated rates of late postnatal transmission, with account taken of loss to follow-up and the observed pattern of weaning, were 12% (95% CI 3-23) and 6% (0-14), respectively. One of the five children whose mothers seroconverted from HIV-negative to HIV-1, and one of seven children whose mothers seroconverted from HIV-2 to dual reactivity, became HIV-1 positive. No case of late postnatal transmission occurred in children born to HIV-2-positive or persistently HIV-negative mothers.

INTERPRETATION

Breastfed children born to mothers seropositive for HIV-1 alone or seropositive for HIV-1 and HIV-2 in Abidjan are at substantial risk of late postnatal transmission. Early cessation of breastfeeding at 6 months of age should be assessed as a possible intervention to reduce postnatal transmission of HIV.

The effect of maternal viral load on the risk of perinatal transmission of HIV-1. New York City Perinatal HIV Transmission Collaborative Study Group

OBJECTIVE

To determine the effect of maternal viral load at delivery on the risk of perinatal transmission of HIV-1.

DESIGN

A nested case-control study within a prospectively followed cohort of HIV-1-infected pregnant women and their infants.

SETTING

The multicenter New York City Perinatal HIV Transmission Collaborative Study.

PARTICIPANTS

Fifty-one women who gave birth to HIV-1 infected infants were frequency-matched within CD4+ cell count quintiles with 54 non-transmitting mothers.

MAIN OUTCOME MEASURES

Maternal quantity of HIV-1 viral RNA was assayed in plasma obtained near delivery using the nucleic acid sequence-based amplification assay system.

RESULTS

Viral RNA was detected in 73 (70%) out of 105 women and the median viral load was 16,000 RNA copies/ml in transmitters and 6,600 in non-transmitters (P < 0.01). When adjusted for maternal CD4+ count near delivery, women with measurable viral load were nearly sixfold more likely to transmit HIV-1 than women with viral load below detection [adjusted odds ratio (AOR), 5.8; 95% confidence interval (CI), 2.2 15.5]. The odds ratio for perinatal transmission of log10 viral load, adjusted for CD4 count was 2.7 (95% CI, 1.5-5.1). When stratified by the stage of HIV-1 disease, the only group with significant association between log10 viral load and transmission were AIDS-free women with CD4+ count > 500 x 10(6)/l (AOR, 9.1; 95% CI, 2.6-31.5).

CONCLUSIONS

High maternal viral load increases the likelihood of perinatal transmission of HIV-1 in women without AIDS and advanced immunosuppression. HIV-1 infected pregnant women without advanced disease, shown by others to have the lowest risk of perinatal transmission, may benefit the most from efforts to identify and decrease viral load at delivery.

Thermal inactivation of bovine immunodeficiency virus

Cell-associated bovine immunodeficiency virus (BIV) and cell-free BIV were subjected to increasing temperatures, including pasteurization conditions. To determine the effect of heat treatment on BIV viability, reverse transcriptase activity and infectivity of the heat-treated virus were assessed. BIV was inactivated by heating to 47 degrees C for 30 min and by low- and high-temperature pasteurization conditions.

Pediatric human immunodeficiency virus infection

In the past decade, an increase in pediatric human immunodeficiency virus (HIV) infection has had a substantial impact on childhood morbidity and mortality worldwide. The vertical transmission of HIV from mother to infant accounts for the vast majority of these cases. Identification of HIV-infected pregnant women needs to be impoved so that appropriate therapy can be initiated for both mothers and infants. While recent data demonstrate a dramatic decrease in HIV transmission from a subset of women treated with zidovudine during pregnancy, further efforts at reducing transmission are desperately needed. This review focuses on vertically transmitted HIV infection in children, its epidemiology, diagnostic criteria, natural history, and clinical manifestations including infectious and noninfectious complications. An overview of the complex medical management of these children ensues, including the use of antiretroviral therapy. Opportunistic infection prophylaxis is reviewed, along with the important role of other supportive therapies.

Transmission of HIV-1 in the breast-feeding process

Current laboratory techniques cannot distinguish the mode of vertical transmission (intrauterine, intrapartum, or postnatal) of human immunodeficiency virus type 1 (HIV-1) from mother to infant. The ability to transmit HIV-1 via breast feeding has been established in 24 case reports, primarily involving mothers who seroconvert after delivery. Whether breast-feeding adds a notable additional risk of HIV-1 infection to the risk from pregnancy is controversial. The importance of the duration and intensity of breast-feeding in modulating the outcome of HIV transmission via breast milk also remains unclear. Factors in breast milk may play important roles in an infant's susceptibility to infection with HIV and in the expression of the virus. Pasteurization and storage enhance the intrinsic, antiviral properties of human milk. Banked human milk is pasteurized to destroy the HIV-1 virus but retains properties that may be helpful to infants of HIV-1-positive mothers in developed countries where breast-feeding is not recommended. For infants in populations where the infant mortality rate is high, the risk of death associated with HIV infection acquired via breast milk is lower than the risk associated with not being breast-fed.

Human immunodeficiency virus type 1-infected cells in breast milk: association with immunosuppression and vitamin A deficiency

Breast milk samples from human immunodeficiency virus type 1 (HIV-1)-seropositive women were analyzed by polymerase chain reaction to determine the prevalence and determinants of HIV-1-infected cells in breast milk. Breast milk samples (212) were collected from 107 women, and 58% of the samples had detectable HIV-1 DNA. The proportion of HIV-1-infected cells in the milk samples ranged from 1 to 3255/10(4) cells. Breast milk samples with detectable HIV-1 DNA were more likely to be from women with absolute CD4 cell counts of < 400 (odds ratio, 3.1; 95% confidence interval [CI], 1.5-7.0). Severe vitamin A deficiency (< 20 micrograms/dL) was associated with a 20-fold increased risk of having HIV-1 DNA in breast milk among women with < 400 CD4 cells/mm3 (95% CI, 2.1-188.5). Women with CD4 cell depletion, especially those with vitamin A deficiency, may be at increased risk of transmitting HIV-1 to their infants through breast milk.

Retroviral Transmission and Breast-feeding

Transmission of animal retroviruses has been demonstrated both for oncogenic retroviruses and animal lentiviruses. In humans, breast-feeding is the major route for mother-to-child transmission of Human T-cell Leukemia/Lymphoma Virus type I (HTLV-I). HTLV-I transmission by breast milk is associated with ingestion of infected cells and can be prevented by formula-feeding. Breast-feeding transmission of the Human Immunodeficiency Virus type 1 (HIV-1) has only been recently recognized as responsible for one to two thirds of mother-to-child transmission in breast-fed populations. A primary HIV-1 infection acquired in mothers after the baby has begun breast-feeding is associated with a particularly high risk of transmission. Breast milk transmission appears to result from the coexistence of HIV-1 and an inadequate humoral response in milk. Due to the dramatic impact of formula-feeding on child morbidity and mortality, it is suggested that present recommendation continue to promote breast-feeding in women living in settings where infectious diseases and malnutrition are the primary causes of infant deaths, as in many developing countries. On the other hand, in settings where infectious diseases and malnutrition are not the primary causes of infant deaths, as in most of the developed world, mothers with a proven HIV-1 infection should be advised not to breast-feed their babies.

Simian immunodeficiency virus infection of macaque primary placental cells

We have characterized the ability of a simian immunodeficiency virus, SIVmne strain E11S, to infect macaque placental trophoblast and Hofbauer cells. These primary placental cells were permissive to SIVmne infection, regardless of gestational age. Virus production by the infected cells was determined as time-dependent viral core antigen p27 production, followed by verification of the proviral gag/LTR DNA sequences in the infected cells using a polymerase chain reaction assay. Of more than six placentas tested, SIVmne infection of placental cells at an early gestational age (i.e., days 55 or 78) produced more than 10-fold the amount of virus core antigen p27 than did placental cells infected at a late gestational age (i.e., days 135 or 165). In addition, SIVmne infection of trophoblast cells was inhibited by SIVmac neutralizing macaque serum but not by normal serum, indicating the specificity of virus infection. Furthermore, the amount of SIV core antigen p27 produced by the virus-infected trophoblast and Hofbauer cells was shown to be dependent on the multiplicity of virus infection. Collectively, our results indicate that macaque trophoblast and Hofbauer cells can be infected by SIV and that both gestational age and viral dose may play a role in the extent of viral infection.

Vertical transmission of human immunodeficiency virus type 1: autologous neutralizing antibody, virus load, and virus phenotype

OBJECTIVE

To evaluate immunologic and virologic correlates of vertical transmission of human immunodeficiency virus type 1 (HIV-1).

DESIGN

Case-control study.

PATIENTS

Women who were prospectively enrolled in a natural history study of HIV-1 infection in women and infants. Sixteen HIV-1-infected women whose infants became infected were matched by CD4+ cell percentage and use of zidovudine during pregnancy with women whose infants did not become infected.

MEASUREMENTS

Maternal autologous neutralizing antibody, virus load determined by RNA-polymerase chain reaction (RNA-PCR), and virus phenotype.

RESULTS

Most women in both groups had low titers of autologous neutralizing antibody, and no difference in neutralizing titers was observed (range, < 4 to 181 in both groups). The HIV-1 copy number in maternal plasma was not significantly different in the two groups but was inversely correlated with maternal CD4+ cell percentage (p < 0.005). Five women in the transmitting group and four in the non-transmitting group had syncytium-inducing (SI) phenotype virus. Two infected infants had SI phenotype virus. The SI phenotype virus was associated with a greater HIV-1 copy number in maternal plasma (p < 0.05) and an increase in the mortality rate for the infants (p < 0.01).

CONCLUSIONS

In women matched for CD4+ cell percentage, low titers of autologous neutralizing antibody, high virus load, and SI phenotype virus were not associated with an increased risk of transmission of HIV-1 to their infants.

Aids em crianças: considerações sobre a transmissão vertical

Trata-se de uma revisão sobre os aspectos epidemiológicos da síndrome de imunodeficiência adquirida em crianças e sobre a transmissão vertical do vírus da imunodeficiência humana (HIV). Discutem-se as diversas vias pelas quais o HIV pode transmitir-se de mãe para filho, abordando questões inerentes à fisiopatologia da infecção intra-útero, periparto e/ou pós-parto.

Mother-to-infant HIV transmission: timing, risk factors and prevention

Identifying when--during pregnancy, delivery or the postnatal period--transmission of human immunodeficiency virus (HIV) from mother to infant usually takes place is critical to the development of methods to prevent maternal-infant transmission. Evidence is reviewed in this paper as to whether transmission occurs prepartum (early or late in gestation), intrapartum, or postpartum with breast feeding. Evidence in support of the notion of prepartum transmission has come from isolation of HIV from aborted fetal organs, comparison of maternal-child viral genotypes and study of neonatal cell-mediated immune responses. Evidence against prepartum transmission is that fewer than half of the children later known to be HIV-infected can be identified by virological tests carried out close to birth. A reduced rate of transmission in infants delivered by Caesarean section, and a reduced risk of transmission to second-born twins delivered vaginally, offers support to the view that intrapartum factors influence the risk of HIV transmission. Transmission through breast feeding can occur if a mother is infected postpartum and seems to pose some additional risk if she is already infected at parturition. The risk of infection increases with the stage of maternal HIV disease, but specific immunological, clinical and viral characteristics need to be investigated further. A clinical trial of zidovudine, used during late pregnancy and delivery and given to the infant at birth, has reported a significant reduction in transmission. Primary prevention of HIV infection in women remains a principal priority.