Breastfeeding and transmission of HIV

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.

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.

Breastfeeding and HIV

Breastfeeding is a route of HIV transmission from an HIV-infected mother to her infant. However, breastfeeding is an important pillar of child survival and the ideal way of feeding an infant, as well as providing a unique biological and emotional basis for child development. This chapter will highlight the dilemma created by the risks and benefits of breastfeeding and will discuss factors which increase the risk of HIV transmission during breastfeeding, as well as strategies which could be employed to reduce these risks. The research agenda is very full as many questions still remain unanswered.

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.

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.

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.

Infant feeding and risk of mother-to-child transmission of HIV-1 in São Paulo State, Brazil. São Paulo Collaborative Study for Vertical Transmission of HIV-1

Although vertical transmission of HIV-1 can occur through breast-feeding, little is known about the effect of colostrum, duration of breast-feeding, mixing feeding, and nipple pathology. We used retrospective cohort data to examine the association between breast-feeding-related factors and transmission of HIV-1 from mother to child in São Paulo State, Brazil. Information on maternal and postnatal factors was collected by medical record review and interview. Infection status was determined for 434 children by anti-HIV-1 tests performed beyond 18 months of age or diagnosis of AIDS at any age. Among 168 breast-fed children, the risk of transmission of HIV-1 was 21%, compared with 13% (p = .01) among 264 children artificially fed. Breast-feeding was independently and significantly associated with mother-to-child transmission of HIV-1 after controlling for stage of maternal HIV-1 disease (odds ratio [OR] = 2.2; 95% confidence interval [CI], 1.3-3.8). A trend was shown toward an increased risk of transmission with longer duration of breast-feeding, a history of bleeding nipples, and introduction of other liquid food before weaning, but these associations were not statistically significant. History of colostrum intake or cracked nipples without bleeding were not associated with transmission. Most of the women who breast-fed were unaware of their HIV-1 infection status at the time of delivery. Avoidance of mixed feeding and withholding of breast-feeding in the presence of bleeding nipples should be considered in further research as strategies to reduce postnatal transmission of HIV-1 in settings in which safe and sustainable alternatives for breast-feeding are not yet available.

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.

Human immunodeficiency virus infection transmitted through breast milk

Perinatal acquisition of human immunodeficiency virus is responsible for most cases of pediatric AIDS. Breast feeding has been found to carry a higher risk of transmission of HIV and is not recommended to HIV infected mothers in the western world. In our country we have to be aware of the increasing incidence of pediatric AIDS and the varied constellation of symptoms it can present with. Also, we have to ensure that safe blood is available to avoid transfusion acquired diseases.

[Symptomatic primary human immunodeficiency virus infection]

Symptomatic primary human immunodeficiency virus (HIV) infection was originally defined as a mononucleosis-like syndrome, with or without lymphocytic meningitis, associated with seroconversion for HIV. However, other protean clinical manifestations have been reported, and diagnosis should be considered in patients with risk factors for HIV who experience acute infectious illness, requiring search for p24 antigenemia and development of HIV antibodies. The clinical presentation of symptomatic HIV infection could predict the subsequent disease progression. In several studies, it is associated with poor prognosis. Pathogenesis relies on the host immune response and on virologic parameters. Early antiretroviral therapy on acute HIV infection could modify the course of infection.

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.

Mode of delivery and gestational age influence perinatal HIV-1 transmission. Italian Register for HIV Infection in Children

Some data suggest that cesarean section reduces mother-to-child HIV-1 transmission. To assess the influence of mode of delivery and other maternal and infant factors on the rate of transmission, we analyzed the data of 1,624 children prospectively followed from birth. Of these, at the last visit 1,033 were > 18 months of age or would have been had they not died of HIV-related illness. Among the 975 first singleton children, 180 [18.5%; 95% confidence limits (CL), 16.1-20.9] acquired infection, as did 8 of 56 (14.3%; 95% CL, 5.1-23.5) second-born children. Multivariate stepwise analysis showed that vaginal delivery and development of symptoms in the mother were significantly and independently associated with a higher transmission rate (vaginal delivery; odds ratio, 1.69; 95% CL, 1.14-2.5; symptoms: odds ratio, 1.61; 95% CL, 1.12-2.3). In contrast, a history of maternal drug use, birth weight, breast-feeding (only 37 infants were breast-fed), and child's sex did not have a significant impact on viral transmission. The percentage of infected children was highest (30.7%) among very premature infants (< or = 32 weeks of gestation); this significant trend subsequently decreased to 11.9% at the week 42 (p < 0.001), suggesting a parallel reduction in peripartum transmission. The reduced rate of infection observed in infants born by cesarean section underlines the urgent need for randomized controlled trials to evaluate the protective role of surgical delivery in preventing perinatal HIV-1 transmission.

Is the risk of perinatal transmission of human immunodeficiency virus increased by the intrapartum use of spiral electrodes or fetal scalp pH sampling?

OBJECTIVE

Our aim was to determine whether the intrapartum use of fetal scalp electrodes or fetal scalp pH sampling increases the rate of perinatal transmission of human immunodeficiency virus.

STUDY DESIGN

The rate of perinatal transmission of human immunodeficiency virus in 31 monitored pregnancies was determined, and those pregnancies were compared with a control group of 117 pregnancies.

RESULTS

The monitored group was comparable to the control group with respect to maternal age, race, human immunodeficiency virus risk behavior, CD4+ cell count, p24 antigen status, and stage of human immunodeficiency virus disease. The mean gestational age at delivery and the mean birth weight were similar in the monitored group and the control group. The perinatal transmission rate for the monitored group (29.0%) was not statistically different from that of the control group (25.6%).

CONCLUSIONS

If confirmed by larger studies, our findings suggest that the intrapartum use of fetal scalp electrodes or fetal scalp pH sampling does not appear to increase the perinatal transmission of human immunodeficiency virus.

Risk of human immunodeficiency virus type 1 transmission through breastfeeding

Detection of human immunodeficiency virus type 1 (HIV-1) in breast milk by culture and polymerase chain reaction does not necessarily mean that breastfeeding is a route of transmission, although evidence from several case-reports points in that direction. We undertook a systematic review of published studies meeting criteria that allowed determination of quantitative risk of transmission via breastfeeding. Based on four studies in which mothers acquired HIV-1 postnatally, the estimated risk of transmission is 29% (95% Cl 16-42%). Analysis of five studies showed that when the mother was infected prenatally, the additional risk of transmission through breastfeeding, over and above transmission in utero or during delivery, is 14% (95% Cl 7-22%). Where there are safe alternatives to breastfeeding, universal named testing of pregnant women would provide an opportunity to advise more infected women not to breastfeed and might thereby reduce the number of vertically infected children. Since breastfeeding protects against infant deaths from infectious diseases, breastfeeding is still recommended where infectious diseases are a common cause of death in childhood, despite the additional risk of HIV transmission.

Detection of HIV-1 genome in leukocytes of human colostrum from anti-HIV-1 seropositive mothers

In order to obtain more information about the presence of HIV-1 in mononuclear cells of colostrum, research was carried out on both the HIV-1 genome in the cellular fraction of colostrum and the viral antibody in cell-free colostrum of eight anti-HIV-1 seropositive asymptomatic mothers. In five cases cell fractions of the colostrum harbored HIV-1 genome by DNA-DNA and DNA-RNA in situ hybridization, whereas viral antibody were detected in all cell-free colostrum specimens. The data confirms the colostrum as a possible route of HIV-1 infection.

Modeling the impact of breast-feeding by HIV-infected women on child survival

This study models the survival outcomes of children born to HIV-infected (human immunodeficiency virus) women who are breast-fed, bottle-fed, and wet-nursed. It is estimated that, given the relative risk of alternatives to maternal milk in developing countries, the probability of HIV transmission via breast milk would need to be at least .12 in a community with an under five child mortality rate from non-HIV causes of 100/1000 live births and at least .27 in a community with a rate of 200/1000 before alternative feeding practices should be recommended even to the known HIV-infected mother who has an available feeding alternative with a relative risk of 2:1. While such a low relative risk may be achievable with wet nursing, most studies report a relative risk of at least 3:1 for bottle feeding. A sensitivity analysis is conducted around the relative risk of child mortality from non-HIV causes associated with different feeding practices. While the critical transmission rate does not vary significantly with a rate of false positives as high as 20 percent on the HIV screening test, the critical transmission rate is very sensitive to the availability of HIV screening. In communities where the HIV prevalence rate among mothers reaches 40 percent, breast-feeding should still be recommended in the absence of HIV screening unless HIV transmission via breast milk surpasses 30 percent.

Do the benefits of breastfeeding outweigh the risk of postnatal transmission of HIV via breastmilk?

Conflicting recommendations have been offered about whether HIV+ mothers should breastfeed. Since there is a strong precedent for US infant feeding practices to be imitated in developing countries, a model was constructed to estimate infant mortality if the CDC admonition for HIV+ mothers not to breastfeed were upheld in less developed settings. Estimates are given for infant mortality in the presence and absence of breastfeeding across several baseline levels of infant mortality and across several theoretical rates of transmission through breastfeeding. The infant mortality associated with HIV infection acquired through breastfeeding is estimated to be lower than the mortality associated with the diseases of infancy that would result if breastmilk were withheld. The difference in these estimates is greater in areas with high baseline levels of infant mortality.

Research on AIDS interventions in developing countries: state of the art

This paper reviews achievements of past and current research on AIDS interventions in developing countries, and identifies three major issues. (1) Several areas of research have been severely neglected, namely transmission from mother to infant, the impact of treating curable STD and transmission in health care settings. (2) AIDS intervention research is mainly concerned with behavioral changes in a very intimate part of human lives, namely sexual relationships. This makes it difficult to design studies that are at the same time ethically acceptable and scientifically sound. A more creative mix of methodologies is needed, that goes hand in hand with a close collaboration between researchers from the social sciences and health sciences field. (3) Counseling is a major aspect of any targeted AIDS intervention program. However, there is no evidence yet for the effectiveness of specific messages and particular forms of counseling. Investigation in this area is urgently needed.