Child-to-breastfeeding woman transmission (CBWT) of HIV occurs when an HIV-infected infant transmits the virus to an HIV-uninfected woman through breastfeeding. Transmission likely occurs as a result of breastfeeding contact during a period of epithelial disruption, such as maternal skin fissures and/or infant stomatitis. Despite extensive epidemiologic and phylogenetic evidence, however, CBWT of HIV continues to be overlooked.
This article summarizes the available evidence for CBWT from nosocomial outbreaks, during which nosocomially HIV-infected infants transmitted the virus to their mothers through breastfeeding. This article also explores the CBWT risk associated with HIV-infected orphans and their female caretakers, and the lack of guidance regarding CBWT prevention in infant feeding recommendations.
We searched online databases including PubMed and Science-Direct for English language articles published from January 1975 to January 2011 using the search terms “HIV,” “perinatal,” “child-to-mother” and “breastfeeding.” The citations from all selected articles were reviewed for additional studies.
We identified 5 studies documenting cases of CBWT. Two studies contained data on the number of HIV-infected women, as well as the proportion breastfeeding. Rates of CBWT ranged from 40% to 60% among women reporting breastfeeding after their infants were infected.
Poor infection control practices, especially in areas of high HIV prevalence, have resulted in pediatric HIV infections and put breast-feeding women at risk for CBWT. Current infant feeding guidelines and HIV prevention messages do not address CBWT, and fail to provide strategies to help women reduce their risk of acquiring HIV during breastfeeding.
Transmission of HIV from HIV-infected children to their uninfected mothers has been documented on several occasions during hospital-based HIV outbreaks among pediatric patients.
References for this review were located through searches of PubMed for English language articles published from January 1975 to January 2011, by use of the terms “HIV,” “perinatal,” “child to mother” and “breastfeeding,” Additional relevant articles published during this period were identified through searches of Google Scholar and ScienceDirect. Reference sections from selected articles were examined for relevant material, and all identified studies were reviewed.
For the 2 studies including information on the number of HIV-infected and uninfected mothers, as well as the proportion of women reporting breastfeeding, odds ratios (ORs) were calculated to determine the odds of HIV infection among mothers who breastfed their infants.
The first documented cases of child-to-breastfeeding woman transmission (CBWT) were reported in 1988 after nosocomial HIV outbreaks at pediatric hospitals in 3 Soviet cities. A total of 152 children and 12 mothers (8%) were found to be HIV-infected.
An additional study including 123 of the mothers of infected infants discovered that 11 of 18 (61%) women who breastfed their children after their child’s admittance to the hospital tested positive for HIV (
A molecular epidemiologic study comparing the HIV-1 strains from infants infected during the outbreak with nonoutbreak strains from individuals infected sexually concluded that individuals infected during the outbreak had a common source. Analysis of nucleotide sequences from 1 infant/mother pair found the strains to be closely related to one another and to those strains obtained from other nosocomially infected infants.
In 1998, 402 children at the Benghazi Children’s Hospital were found to be infected with HIV.
Epidemiologic investigations found that the mothers were likely infected by their infants.
The presence of nipple fissures was also statistically associated with HIV infection in breastfeeding women (OR: 83.0; 95% CI: 8.9–3676.9).
From 2006 to 2007, an outbreak of HIV was identified at 3 children’s hospitals in Shymkent, Kazakhstan. One hundred forty-three cases of HIV were identified in previously hospitalized children between the ages of 1 month and 3 years.
At least 13 (9.1%) of the mothers of these infants were also infected with HIV during the course of the outbreak.
Between 2006 and 2007, 86 cases of HIV infection were identified at pediatric hospitals in southern Kyrgyzstan.
By the end of 1990, the Romanian Ministry of Health had reported 1168 cases of AIDS, mostly from hospitals and orphanages. Thirty-three percent of cases occurred in children ≤ 1 year of age, and 94% in children under the age of 13. Although the majority of these children were wards of the state, approximately 38% of cases occurred among nonorphans. A number of cases were believed to have been infected nosocomially, although 57% of children had no known risk factors.
After locating and testing 493 (45%) of the mothers of infected children, 37 women (8%) were found to be infected with HIV. Eighteen of 30 women (60%) questioned had no known risk factors for HIV infection, including clotting disorders, receipt of a blood transfusion, a history of injection drug use or a sexual contact with an individual infected with HIV/AIDS.
Although no studies were performed to determine the direction of transmission, only 30 of the 74 adult cases of AIDS that had been reported in Romania at this time occurred in women, compared with 1094 pediatric cases.
Although published examples of CBWT occurred after pediatric nosocomial HIV outbreaks, transmission is possible in any instance where an HIV-infected child is breastfed by an uninfected woman, including occasions when an HIV-infected child is orphaned and later breastfed by an uninfected female caretaker.
Wet-nursing, the complete nursing of another’s infant, still occurs in many parts of the world, although its acceptability varies. Cross-nursing, the occasional nursing of another’s infant while the mother continues to nurse her own child, also remains common in many areas.
Cross-feeding typically occurs on more informal basis than wet-nursing, although research on the topic is limited.
In many African countries, where grandmothers typically bear the responsibility for childcare if a mother is ill or absent, nonpuerperal-induced lactation is sometimes practiced.
Especially in high HIV-prevalence areas, these practices may put women or infants at risk for HIV transmission. This is particularly concerning with regard to cross-nursing, which may involve multiple infants and women over long periods of time. Even when knowledge of HIV transmission through breast milk from mother to child is high, women may not be aware of their risk of HIV acquisition from an infected infant while breastfeeding. In cross-nursing situations, the direction of causation may be difficult to determine, although HIV could potentially be passed from one infected individual to multiple infants and mothers.
The risk for CBWT resulting from HIV-infected orphans is not known, and the number of HIV-infected orphans of breastfeeding age remains difficult to estimate. Worldwide, an estimated 15 million children have lost one or both parents to HIV/AIDS.
It remains unclear what proportion of female caretakers choose to breastfeed orphans, or what proportion of cross-feeding or wet-nursing involves HIV-infected orphans. Although cases of CBWT have not yet been documented in this population, the conditions necessary for HIV transmission from child to caretaker are in place.
World Health Organization guidelines on infant feeding make recommendations on breastfeeding by HIV-infected women. The World Health Organization guidelines in 2003 suggested the use of a wet nurse for HIV-infected mothers who chose not to breastfeed their infants.
These provisions were designed to protect the health of infants, and focused exclusively on the characteristics of the woman agreeing to act as wet nurse. They included guidance on monitoring her HIV status, ensuring her overall health and checking her ability to properly breastfeed the infant in her care.
The 2006 HIV and Infant Feeding Update recommended that HIV-infected women should only be counseled thoroughly on infant feeding options such as nursing, expressed milk heat treatment or milk banks if the woman specifically requested additional information on these topics.
The most recent 2010 recommendations make no mention of the practice of wet-nursing, or the risk of HIV transmission to breastfeeding mothers or caregivers from infected infants. Future recommendations should include guidance on CBWT and the risk of HIV transmission for women who may choose to breastfeed HIV-infected or HIV-status unknown infants.
New HIV infections in breastfeeding infants put seronegative women at risk of acquiring HIV. Unfortunately, when CBWT does occur, it may often be overlooked or may be wrongly attributed to mother-to-child transmission, especially in high HIV-prevalence areas. Although significant advances have been made, mother-to-child transmission remains the leading cause of pediatric HIV infection worldwide. Preventing CBWT begins with the elimination of new HIV infections in children, including vertical transmission from mother-to-child, which leads to an estimated 370,000 cases of perinatally acquired HIV each year.
Other, less common modes of pediatric HIV transmission such as healthcare-associated HIV infections are also of special concern for CBWT. Infection control, proper sterilization and sufficient supplies continue to be a challenge in many healthcare facilities, especially in low-resource settings. Current rates of unsafe injections, transfusion-transmitted infections and nosocomial infections remain unacceptably high, particularly among pediatric patients who are exposed to injections at a greater rate than adults.
Although no documented cases have been published to date, cross-feeding or wet-nursing of perinatally HIV-infected infants could put seronegative women at risk for CBWT. Although cross-nursing or wet-nursing may be an alternative feeding strategy for orphaned infants with potential benefits in terms of nutrition and protection from diarrheal diseases, evidence for CBWT demonstrates that the decision by a HIV-negative woman to breastfeed an HIV-infected infant carries substantial risk. If female caretakers are considering breastfeeding HIV-exposed orphans, counseling women on the potential for CBWT and testing both the child and woman for HIV would help make informed feeding decisions and reduce their risk. Additional research and surveillance could better determine the magnitude of risk associated with this practice, and identify instances of CBWT between HIV-infected orphans and their breastfeeding caretakers.
Transmission of an infectious agent from an infant to a breastfeeding caretaker has been documented previously. Syphilis is known to have passed from congenitally infected infants to wet nurses through breastfeeding.
Continued research is needed in countries with high rates of HIV, mother-to-child transmission, orphanhood and wet-nursing or cross-feeding to quantify the prevalence and magnitude of risk associated with CBWT. Policy analysis is needed to weigh the risks and benefits of optimal infant nutrition and the prevention of CBWT. Support should also be continued for programs working to eliminate mother-to-child HIV transmission, which reduce the number of HIV-infected, breastfeeding children and prevent opportunities for CBWT to occur.
This article is the first review of HIV transmission from infected infants to breastfeeding women. As such, it is limited by the small amount of published data, and relies heavily on retrospective studies. Case-control studies of CBWT based on mother’s self-reported infant feeding modality may be biased as a result.
Published instances of CBWT have documented rates of transmission during breastfeeding as high as 40–60%. Although this risk is substantial, we were unable to calculate the number of women who may be at risk for CBWT globally, or compare this risk with other, better known routes of transmission in women of reproductive age. Data on the transmission of resistant strains is unavailable, and the issue remains an avenue for future research. Finally, this study was limited by a lack of information on pediatric risk factors for CBWT such as viremia, CD4 counts or antiretroviral exposure.
While significant gains have been made in reducing global rates of mother-to-child HIV transmission, CBWT has rarely been addressed. The spread of HIV from an infected infant to a mother or caretaker is preventable. Programs to prevent mother-to-child transmission, elimination of unnecessary injections in children, better infection control practices in hospitals, and national blood safety guidelines and hemovigilance systems would likely reduce the number of infants infected with HIV and put fewer breastfeeding women at risk for CBWT. Improved and expanded anti-malaria programs would also reduce the prevalence of severe childhood anemia and lessen the need for pediatric transfusions. Preventing primary infections and providing appropriate, timely treatment for HIV-infected parents can also decrease the number of AIDS orphans and non-biological caretakers, which in turn reduces the opportunities for CBWT to occur. As with other forms of person-to-person HIV transmission, timely diagnoses are the key to preventing further spread. Scaling up early infant HIV testing capacity and access could prevent CBWT by identifying pediatric infections promptly, and providing critical treatment and counseling. Finally, comprehensive infant feeding recommendations and prevention programs should include information about CBWT in order to make women aware of their risks and advise them on the best feeding practices in the context of both maternal and infant HIV infection.
The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
Contributors: KML performed the literature searches, checked all full-text articles, constructed figures, interpreted data and wrote the first draft of the manuscript. PHK contributed to the writing and editing of the manuscript, data interpretation as well as revision of the figures. AWT assisted in data interpretation and figure revision, as well as manuscript editing. EDR participated in discussion of the findings, contributed subject matter expertise regarding global pediatric and perinatal HIV, and assisted in manuscript editing. SRN supervised the review and editing process, and contributed to the writing and editing of the manuscript. All authors participated in writing the final article.
The authors have no funding or conflicts of interest to disclose.
Documented Cases of Child-to-breastfeeding Woman Transmission of HIV
| Variables | Former USSR | Sensitivity Analysis | Libya | Sensitivity Analysis |
|---|---|---|---|---|
| Children included | 123 | — | 118 | — |
| Proportion of mothers included who were HIV-infected | 12/123 (9.8%) | — | 18/102 (17.6%) | — |
| HIV-infected women with no known HIV risk factors | 8/12 (66.7%) | — | 14/18 (77.8%) | — |
| Proportion of HIV-infected women reporting breastfeeding | 11/11 (100%) | 11/12 (91.7%) | 15/16 (93.8%) | 15/18 (83.3%) |
| Proportion of HIV-uninfected women reporting breastfeeding | 7/101 (6.9%) | 17/111 (15.3%) | 23/77 (29.9%) | 30/84 (35.7%) |
| Breastfeeding odds ratio (95% CI) | 289.8 (15.5–5412) | 60.8 (7.4–502.3) | 35.2 (4.4–282.5) | 9.0 (2.4–33.6) |
| Proportion of all women reporting breastfeeding who were HIV- infected | 11/18 (61.1%) | 11/28 (39.3%) | 15/38 (39.5%) | 15/45 (33.3%) |
Includes only studies that reported the proportion of HIV-infected and HIV-uninfected women reporting breastfeeding.
The sensitivity analysis assumes that the 1 HIV-infected woman with missing data on breastfeeding had not breastfed, whereas all 10 HIV-uninfected women missing infant feeding data had breastfed.
The sensitivity analysis assumes the 2 HIV-infected women missing data on breastfeeding had not breastfed, and that all 7 HIV-uninfected women with missing infant feeding data had breastfed.
Three women reported receiving injections at the same hospital as the infected children. Two women had a seropositive sexual contact.
Four HIV-infected women reported needle sticks or intravenous treatment during the outbreak.
One HIV-infected woman was missing data on breastfeeding.
Two HIV-infected women were missing data on breastfeeding.
Ten HIV-uninfected women were missing data on breastfeeding.
Seven HIV-uninfected women were missing data on breastfeeding.
— indicates data not available.