Infant morbidity, mortality, and breast milk immunologic profiles among breast-feeding HIV-infected and HIV-uninfected women in Botswana

BACKGROUND: Infants of human immunodeficiency virus (HIV)-infected women have high mortality, but the immunologic integrity and protection afforded by the breast milk of HIV-infected women is unknown. METHODS: We determined morbidity and mortality by 24 months among breast-fed infants of 588 HIV-infected and 137 HIV-uninfected women followed-up in a clinical trial in Botswana. A matched case-control study compared clinical, behavioral, and breast milk immunologic parameters among 120 HIV-infected women by infant outcome. Breast milk factors were also compared between HIV-infected and HIV-uninfected women. RESULTS: Twenty-four-month mortality was 29.5% among HIV-infected infants, 6.7% among HIV-exposed uninfected infants, and 1.6% among HIV-unexposed infants. No differences were detected in breast milk immunologic profiles of HIV-infected women whose infants were either ill or well. Discontinuation of breast-feeding was the strongest predictor of illness (P<.001). Levels in breast milk of pathogen-specific immunoglobulin (Ig) G and IgA to Haemophilus influenzae, Campylobacter jejuni, Helicobacter pylori, Streptococcus pneumoniae, and innate immune factors were not lower among HIV-infected women than among HIV-uninfected women. CONCLUSIONS: Mortality was higher among HIV-infected and HIV-exposed infants than among HIV-unexposed infants. However, the immunologic profiles of breast milk among HIV-infected women were intact, and discontinuation of breast-feeding was the primary risk for infant morbidity. Thus, the breast milk of HIV-infected women may confer protection against common infant pathogens. TRIAL REGISTRATION: (ClinicalTrials.Gov) identifiers: NCT00197691 and NCT00197652.     

Early growth of infants of HIV-infected and uninfected Zambian women

OBJECTIVE: Parental HIV infection may affect even those exposed children who remain uninfected. We investigated early growth, an indicator of overall health, of infants born to Zambian mothers recruited for a study of breastfeeding and postpartum health. METHODS: HIV-infected and uninfected women in Lusaka were followed regularly from late pregnancy to 16 weeks postpartum. Infant weight and length were measured at birth, 6 and 16 weeks. Infant HIV status could not be specifically determined in this cohort so comparisons were between all infants of HIV-uninfected mothers (n = 184) and those infants of HIV-infected mothers who were known to be alive and showed no clinical evidence of HIV infection at age 2-4 years (n = 85). RESULTS: Most infants were exclusively or predominantly breastfed until 16 weeks. At all time points infants of HIV-infected mothers tended to have lower weight and length standard deviation (Z) scores (significant for weight at 6 weeks; P = 0.04), even after adjustment for their lower gestational age at birth, compared with infants of uninfected mothers. In multivariate analyses the major factors affecting weight or length at 6 or 16 weeks of age were birth weight or length, and maternal subclinical mastitis, primiparity and weight during pregnancy. CONCLUSIONS: Early growth of infants of HIV-infected mothers is less than that of uninfected mothers, in part associated with subclinical mastitis, and this effect cannot be overcome with intensive support of mothers to follow international recommendations regarding exclusive breastfeeding.     

Placental abnormalities associated with human immunodeficiency virus type 1 infection and perinatal transmission in Bangkok, Thailand

The effects of human immunodeficiency virus (HIV) type 1 on the placenta and the role of the placenta in mother-to-child HIV-1 transmission are not well understood. Placentas from 78 HIV-infected and 158 HIV-uninfected women were examined as part of a prospective perinatal HIV transmission study in Bangkok. HIV-infected women were more likely than HIV-uninfected women to have chorioamnionitis (odds ratio [OR], 2.1; P=.03), placental membrane inflammation (PMI; OR, 2. 7; P=.02), and deciduitis (OR, 2.3; P=.03) and less likely to have villitis (OR, 0.3; P=.02). However, among HIV-infected women, fewer women who transmitted infection to their child had chorioamnionitis (relative risk [RR], 0.2; P=.03), funisitis (RR, 0.4; P=.1), or PMI (RR undefined; P=.03). These findings suggest that, in this population, HIV-infected women are at increased risk for placental membrane inflammatory lesions, but that placental inflammatory lesions are not associated with increased perinatal HIV transmission.     

Human immunodeficiency virus load in breast milk, mastitis, and mother-to-child transmission of human immunodeficiency virus type 1.

Human immunodeficiency virus (HIV) type 1 load in breast milk and mastitis were examined as risk factors for vertical transmission of HIV-1. Six weeks after delivery, HIV-1 load and sodium (an indicator of mastitis) were measured in breast milk from 334 HIV-1-infected women in Malawi. Median breast milk HIV-1 load was 700 copies/mL among women with HIV-1-infected infants versus undetectable (<200 copies/mL) among those with uninfected infants, respectively (P<. 0001). Elevated breast milk sodium levels consistent with mastitis occurred in 16.4% of HIV-1-infected women and were associated with increased vertical transmission of HIV-1 (P<.0001). Median breast milk HIV-1 load was 920 copies/mL among women with versus undetectable among those without elevated breast milk sodium levels, respectively (P<.0001). Mastitis and breast milk HIV-1 load may increase the risk of vertical transmission of HIV-1 through breast-feeding.     

Prevalence of sexually transmitted infections among women attending antenatal clinics in Tanga, north eastern Tanzania

This study aimed to determine the prevalence of sexually transmitted infections (STIs) among HIV-infected and uninfected pregnant women in Tanga, Tanzania. Retrospective data on syphilis and HIV status during 2008-2010 were collected from antenatal clinic (ANC) records. Prospective data were collected from HIV-infected (n = 105) and HIV-uninfected pregnant women (n = 100) attending ANCs between April 2009 and August 2010. Syphilis prevalence showed a declining trend (3.1%, 1.4% and 1.3%), while HIV prevalence was stable (6.1%, 6.4% and 5.4%) during 2008-2010. HIV-infected women had significantly higher prevalence of trichomoniasis (18.8% versus 5.0%; P < 0.003) and candidiasis (16.5% versus 2.0%; P < 0.001) while the higher rate of gonorrhoea (3.5% versus 0%; P = 0.095) was not statistically significant when compared with HIV-uninfected women. There were no statistically significant differences in prevalence of chlamydial infection (0% versus 3.0%; P = 0.156) or syphilis (2.4% versus 3.0%; P = 1) between HIV-infected and uninfected women. Other STIs were common in both HIV-infected and uninfected pregnant women.     

T-helper cell responses to HIV envelope peptides in cord blood: protection against intrapartum and breast-feeding transmission

BACKGROUND: Acquired HIV-specific cell-mediated immune responses have been observed in exposed-uninfected individuals, and it has been inferred, but not demonstrated, that these responses constitute a part of natural protective immunity to HIV. This inference was tested prospectively in the natural exposure setting of maternal-infant HIV transmission in a predominantly breast-fed population. METHODS: Cord blood from infants of HIV-seropositive women in Durban, South Africa, were tested for in vitro reactivity to a cocktail of HIV envelope peptides (Env) using a bioassay measuring interleukin-2 production in a murine cell line. Infants were followed with repeat HIV RNA tests up to 18 months of age to establish which ones acquired HIV-infection. RESULTS: T-helper cell responses to Env were detected in 33 out of 86 (38%) cord blood samples from infants of HIV-seropositive women and in none of nine samples from seronegative women (P = 0.02). Among infants of HIV-seropositive mothers, three out of 33 with T-helper responses to Env were already infected before delivery (HIV RNA positive on the day of birth), two were lost to follow-up, and none of the others (out of 28) were found to be HIV infected on subsequent tests. In comparison, six out of 53 infants unresponsive to Env were infected before delivery, and eight out of 47 (17%) of the others were found to have acquired HIV infection intrapartum or post-partum through breast-feeding (P = 0.02). CONCLUSIONS: T-helper cell responses to HIV envelope peptides were detected in more than one-third of newborns of HIV-infected women; no new infections were acquired by these infants at the time of delivery or post-natally through breast-feeding if these T-helper cell responses were detected in cord blood.     

Postnatal care utilization and local understandings of contagion among HIV-infected and uninfected women in rural,southern Zambia

Postnatal care is essential for ensuring the optimal health of newborns and necessary for the prevention of maternal-to-child human immunodeficiency virus (HIV) transmission as well as the early diagnosis and treatment of HIV-infected infants. However, coverage of postnatal care is low in many rural areas of sub-Saharan Africa. We examined women’s experiences of accessing formal postnatal care for their HIV-exposed newborns, comparing reports of HIV-infected and uninfected women in an HIV-endemic area of rural southern Zambia. We conducted 24 qualitative in-depth interviews with recently delivered women in a rural region of southern Zambia, including 8 with women who were willing to disclose their HIV infection status and answer additional questions. Data were transcribed, coded and analyzed using thematic analysis techniques. HIV-infected women identified more disincentives and reported more negative experiences accessing postnatal care than HIV-uninfected women. A local notion of contagion holds that healthy infants may become sick with chibele, a fatal, febrile illness, if exposed to another infant who is taking “strong medicine”, such as antiretroviral drugs. Thus, HIV-uninfected women expressed objections to sharing clinics with women and infants who were presumed to be under treatment. Additionally, women reported receiving better treatment from staff at HIV clinics compared to general pediatric clinics. Due to these tensions, HIV-infected women were less likely to visit a clinic for newborn care if the clinic or waiting area was a common space used by HIV-uninfected women and their children. When integrating programs for HIV with maternal and child health care, these nuanced tensions between groups of patients must be recognized and resolved.     

Effect of HIV status on fertility desire and knowledge of long-acting reversible contraception of postpartum Malawian women

The objectives of this study were to describe the most recent pregnancy intentions and family planning preferences of HIV-infected and HIV-uninfected postpartum Malawian women, and to assess whether HIV status is associated with fertility desire and knowledge of intrauterine contraception (IUC) and the subdermal contraceptive implant. We conducted a cross-sectional analysis of the baseline characteristics of Malawian women enrolled in a prospective cohort study assessing postpartum contraceptive uptake and continuation. Women at a government hospital completed a baseline survey assessing reproductive history, family planning preferences, and knowledge of IUC and the implant. We used Pearson's chi-square tests to compare these parameters between HIV-infected and HIV-uninfected women. Modified Poisson regression was performed to assess the association between HIV status and fertility desire and knowledge about IUC and the implant. Of 634 postpartum women surveyed, HIV-infected women were more likely to report their most recent pregnancy was unintended (49% vs. 37%, p = 0.004). Nearly all women (97%) did not want a child in the next 2 years, but HIV-infected women were more likely to desire no more children (adjusted prevalence ratio [PR]: 1.59; 95% confidence interval [CI]: 1.33, 1.89). HIV-infected women were also less likely to know that IUC (adjusted PR: 0.72; 95% CI: 0.61, 0.84) and the implant (adjusted PR: 0.83; 95% CI: 0.75, 0.92) are safe during breast-feeding. Postpartum women strongly desire family spacing and many HIV-infected postpartum women desire no more children, suggesting an important role for these long-acting methods. Education about the efficacy and safety of IUC and the implant particularly during breast-feeding may facilitate postpartum use.     

Relationship between smoking and human papillomavirus infections in HIV-infected and -uninfected women

Background. Smoking may increase the risk of cervical cancer, a disease that is related to human papillomavirus (HPV) infection. However, the effects of smoking on the natural history of HPV are poorly understood, especially in women coinfected with human immunodeficiency virus (HIV).Methods. HIV-infected (n=1797) and HIV-uninfected (n=496) women were assessed every 6 months for type-specific HPV DNA. Smoking status was self-reported. Covariates included age, parity, sexual behavior, HIV load, CD4(+) T cell count, and antiretroviral therapy.Results. Smoking was positively associated with HPV prevalence at baseline in HIV-infected women (P=.002) and was significantly associated with type-specific HPV detection (e.g., type 18, odds ratio [OR], 2.45; 95% confidence interval [CI], 1.86-3.22). In Cox models, detection of HPV was significantly associated with smoking in HIV-infected women (relative hazard [RH], 1.33; 95% CI, 1.10-1.60; P=.003), but HPV persistence was not (RH, 0.97; 95% CI, 80-1.16; P=.72). The overall likelihood of acquiring persistent HPV was higher in smokers (OR, 1.39; 95% CI, 1.05-1.86; P=.023) because of greater incidence.Conclusions. Among HIV-infected women, smoking is associated with a significantly higher prevalence and incidence of HPV infection. Smoking during HIV infection may alter the natural history of HPV infection and increase the risk of cervical disease.     

Dilation of the aortic root in children infected with human immunodeficiency virus type 1: The Prospective P2C2 HIV Multicenter Study

BACKGROUND: Vascular lesions have become more evident in human immunodeficiency virus type 1 (HIV)-infected patients as the result of earlier diagnosis, improved treatment, and longer survival. Aortic root dilation in HIV-infected children has not previously been described. This study was undertaken to determine the prevalence of aortic root dilation in HIV-infected children and to evaluate some of the potential pathogenic mechanisms. METHODS: Aortic root measurements were incorporated into the routine echocardiographic surveillance of 280 children of HIV-infected women: an older cohort of 86 HIV-infected children and a neonatal cohort of 50 HIV-infected and 144 HIV-uninfected children. RESULTS: By repeated-measures analyses, mean aortic root measurements were significantly increased in HIV-infected children versus HIV-uninfected children (P values of < or =.04 and < or =.005 at 2 and 5 years of age, respectively, for aortic annulus diameter, sinuses of Valsalva, and sinotubular junction). Heart rate, systolic blood pressure, stroke volume, hemoglobin, and hematocrit were not significantly associated with aortic root size. Left ventricular dilation, increased serum HIV RNA levels, and lower CD4 cell count measurements were associated with aortic root dilation at baseline. CONCLUSIONS: Mild and nonprogressive aortic root dilation was seen in children with vertically transmitted HIV infection from 2 to 9 years of age. Aortic root size was not significantly associated with markers for stress-modulated growth; however, aortic root dilation was associated with left ventricular dilation, increased viral load, and lower CD4 cell count in HIV-infected children. As prolonged survival of HIV-infected patients becomes more prevalent, some patients may require long-term follow-up of aortic root size.     

Evidence from Zaire that breast-feeding by HIV-1-seropositive mothers is not a major route for perinatal HIV-1 transmission but does decrease morbidity

Breast-feeding as a route of HIV-1 transmission during infancy but also as a protective measure against early childhood morbidity has been investigated prospectively in children born to HIV-1-seropositive mothers and control children born to age- and parity-matched HIV-1-seronegative women. The mothers of all study children had been enrolled antenatally at a maternity hospital in Kinshasa, Zaire, which served a relatively affluent group of women who sometimes chose not to breast-feed their infants. In 106 children born to HIV-1-seropositive women, the rate of HIV-1 transmission was 21% in 28 infants exclusively breast-fed, 19% in 68 infants both breast- and bottle-fed and 0% in 10 infants who were bottle-fed only (P = 0.35). In contrast, non-HIV-1-infected children of both HIV-1-seropositive and HIV-1-seronegative mothers who were exclusively breast-fed compared with uninfected children who were not exclusively breast-fed had significantly lower incidence rates of acute diarrhea, fever and lower respiratory tract infection. The lack of a dose-response effect between breast-feeding and perinatal HIV-1 transmission and the presence of a protective effect of breast-feeding against common causes of early childhood morbidity and mortality support the current World Health Organization recommendation that breast-feeding should continue to be promoted in all developing countries, including those with high HIV-1 prevalence rates in women of childbearing age.     

Breastmilk RNA viral load in HIV-infected South African women: effects of subclinical mastitis and infant feeding

OBJECTIVE: To investigate determinants of breastmilk RNA viral load among HIV-infected South African women, with particular attention to infant feeding mode and subclinical mastitis. DESIGN: Observational, longitudinal study. METHODS: Information on current infant feeding practice and a spot milk sample from each breast were obtained from 145 HIV-infected lactating women at 1, 6 and 14 weeks postpartum. The sodium/potassium (Na+/K+) ratio in milk was taken as an indicator of subclinical mastitis. The association between milk RNA viral load and maternal and infant characteristics was investigated using uni- and multivariate models. RESULTS: Milk viral load was below the limit of detection of the HIV RNA assay (< 200 copies/ml) in 63/185 (34.1%), 73/193 (37.8%) and 68/160 (42.5%) of samples at 1, 6 and 14 weeks, respectively. Multivariate models predicted between 13 and 26% of variability in milk viral load in the first 14 weeks. Low blood CD4 cell count (< 200 x 10(6) cells/l) during pregnancy and raised milk Na+/K+ ratio were significantly associated with raised milk RNA viral load at all times, but there were no consistent associations between infant feeding mode and RNA viral load in milk. There was a non-significant trend for the six infants known to be infected postnatally, compared with the 88 infants who remained uninfected, to have been exposed to breastmilk of higher viral load at each time point. CONCLUSIONS: Breast milk HIV RNA viral load in the first 14 weeks of life varied; high levels were associated with subclinical mastitis and severe maternal immunosuppression. Multivariate models had limited predictive value for milk RNA viral load, illustrating the multiple contributors to viral load.     

Impact of breast-feeding on Giardia lamblia infections in Bilbeis, Egypt

A total of 152 infants were followed from birth to 1 year of age in a rural community of Egypt to document Giardia lamblia infection and to determine the effect of breast-feeding on enteric infections by this protozoan. Asymptomatic Giardia infections persisted as long as 4 months, with a mean duration of excretion of 7.18 weeks. The incidence of asymptomatic infection was 4.5 episodes per child-year. Exclusively breast-fed infants had lower risk for asymptomatic (odds ratio [OR] = 0.66, 95% confidence interval [CI] = 0.45-0.96, P < 0.05) and symptomatic infections (relative risk [RR] = 0.50, 95% CI = 0.27-0.90, P < 0.05). Furthermore, breast-fed infants had fewer clinical manifestations, including mucus in stool (23.8% versus 76.2%, P = 0.08), loss of appetite (17.6% versus 82.3%, P < 0.05), and abdominal tenderness (17% versus 82.9%, P < 0.05) compared with infants who were not exclusively breast-fed. Breast-feeding should be considered as an effective means to prevent Giardia infections and should be encouraged in regions where G. lambia is highly endemic.     

Women's choices regarding HIV testing,disclosure and partner involvement in infant feeding and care in a rural district of Malawi with high HIV prevalence

The influence of HIV-related stigma on women's choices with regard to HIV testing, disclosure and partner involvement in infant feeding and care is not well understood in rural Malawi but may influence the risk of vertical HIV transmission and infant health. In a study of HIV-infected and -uninfected women in 20 rural locations in Zomba District, Malawi, mothers were questioned at 18–20 months post-partum about these issues. Ten per cent of women claimed unknown HIV status in labour so HIV testing should be routinely offered in Labour & Delivery wards. HIV-infected women were somewhat less likely to disclose to their partners than HIV-uninfected women (89 and 97%, respectively; p = 0.007) or to be cohabiting with partners during pregnancy (74 and 86%, respectively; p = 0.03). Partners of women were less inclined to disclose their HIV testing or HIV status (49 and 66% of partners of HIV-infected and -uninfected women, respectively). Greater partner testing and disclosure may improve prevention of mother to child transmission of HIV (PMTCT) in this population. A majority of women were inclined to make feeding decisions on their own, whereas most felt that other health-related decisions should also involve the father. Most mothers believe that exclusive breast feeding (EBF) is the best infant feeding method (for the first six months) but it was actually practiced by a minority of women (20% of HIV-infected and 5% of HIV-uninfected mothers; p = 0.01). EBF needs systematic support in order to be practised.     

HIV-1 disease progression in breast-feeding and formula-feeding mothers: a prospective 2-year comparison of T cell subsets, HIV-1 RNA levels, and mortality

BACKGROUND: There is conflicting evidence regarding the effects of breast-feeding on maternal mortality from human immunodeficiency virus type 1 (HIV-1) infection, and little is known about the effects of breast-feeding on markers of HIV-1 disease progression. METHODS: HIV-1-seropositive women were enrolled during pregnancy and received short-course zidovudine. HIV-1 RNA levels and CD4 cell counts were determined at baseline and at months 1, 3, 6, 12, 18, and 24 postpartum and were compared between breast-feeding and formula-feeding mothers. RESULTS: Of 296 women, 98 formula fed and 198 breast-fed. At baseline, formula-feeding women had a higher education level and prevalence of HIV-1-related illness than did breast-feeding women; however, the groups did not differ with respect to CD4 cell counts and HIV-1 RNA levels. Between months 1 and 24 postpartum, CD4 cell counts decreased 3.9 cells/ microL/month (P<.001), HIV-1 RNA levels increased 0.005 log(10) copies/mL/month (P=.03), and body mass index (BMI) decreased 0.03 kg/m(2)/month (P<.001). The rate of CD4 cell count decline was higher in breast-feeding mothers (7.2 cells/ microL/month) than in mothers who never breast-fed (4.0 cells/ microL/month) (P=.01). BMI decreased more rapidly in breast-feeding women (P=.04), whereas HIV-1 RNA levels and mortality did not differ significantly between breast-feeding and formula-feeding women. CONCLUSIONS: Breast-feeding was associated with significant decreases in CD4 cell counts and BMI. HIV-1 RNA levels and mortality were not increased, suggesting a limited adverse impact of breast-feeding in mothers receiving extended care for HIV-1 infection.     

Effects of a single large dose of vitamin A, given during the postpartum period to HIV-positive women and their infants, on child HIV infection, HIV-free survival, and mortality

BACKGROUND: Low maternal serum retinol level is a risk factor for mother-to-child transmission (MTCT) of human immunodeficiency virus (HIV). Multiple-large-dose vitamin A supplementation of HIV-positive children reduces mortality. The World Health Organization recommends single-large-dose vitamin A supplementation for postpartum women in areas of prevalent vitamin A deficiency; neonatal dosing is under consideration. We investigated the effect that single-large-dose maternal/neonatal vitamin A supplementation has on MTCT, HIV-free survival, and mortality in HIV-exposed infants. METHODS: A total of 14,110 mother-infant pairs were enrolled < or =96 h after delivery, and both mother and infant, mother only, infant only, or neither received vitamin A supplementation in a randomized, placebo-controlled trial with a 2 x 2 factorial design. All but 4 mothers initiated breast-feeding. A total of 4495 infants born to HIV-positive women were included in the present analysis. RESULTS: Neither maternal nor neonatal vitamin A supplementation significantly affected postnatal MTCT or overall mortality between baseline and 24 months. However, the timing of infant HIV infection modified the effect that supplementation had on mortality. Vitamin A supplementation had no effect in infants who were polymerase chain reaction (PCR) positive [corrected] for HIV at baseline. In infants who were PCR negative at baseline and PCR positive at 6 weeks, neonatal supplementation reduced mortality by 28% (P=.01), but maternal supplementation had no effect. In infants who were PCR negative at 6 weeks, all 3 vitamin A regimens were associated with ~2-fold higher mortality (P< or =.05). CONCLUSIONS: Targeted vitamin A supplementation of HIV-positive children prolongs their survival. However, postpartum maternal and neonatal vitamin A supplementation may hasten progression to death in breast-fed children who are PCR negative at 6 weeks. These findings raise concern about universal maternal or neonatal vitamin A supplementation in HIV-endemic areas.     

Influence of body mass index on pregnancy outcomes among HIV-infected and HIV-uninfected Zambian women

OBJECTIVES: To determine the influence of body mass index (BMI) on pregnancy outcomes of HIV-infected and HIV-uninfected Zambian women and to assess the possible role of BMI on mother-to-child transmission rate of HIV. METHODS: We analysed data from a clinical trial on nevirapine administration for the prevention of mother-to-child transmission of HIV in Lusaka, Zambia. Demographic characteristics, medical information and pregnancy outcomes were used in this secondary analysis. RESULTS: A total of 1211 women were included in this analysis and 36% were HIV-infected. Among HIV-infected women, maternal parity and prior stillbirths increased with increasing BMI in univariate analysis. Mean birth weight rose as well at 28.3 g [95% confidence interval (CI)=14.0-42.6] of infant weight per BMI unit. Transmission of HIV from mother to child appeared inversely related to BMI when compared according to BMI quartile (P for trend=0.07). In the HIV-uninfected group, infant birth weight increased with increasing BMI, at 32.7 g (95% CI=23.5-41.9) of infant weight per BMI unit. CONCLUSION: Birth weight increased alongside BMI in both HIV-infected and HIV-uninfected women. There is a suggestion that women with lower BMI have a greater risk of perinatal HIV transmission, even after adjustments for HIV viral load and CD4 count.     

Higher seroprevalence of Entamoeba histolytica infection is associated with human immunodeficiency virus type 1 infection in Taiwan

We assessed the seroprevalence of Entamoeba histolytica infection using indirect hemagglutination antibody (IHA) assay among 667 HIV-infected persons (group A), 1,311 asymptomatic HIV-uninfected persons seeking anonymous HIV testing (group B), 616 HIV-uninfected controls with gastrointestinal symptoms (diarrhea and/or liver abscess) seeking medical care (group C), and 2,500 healthy controls undergoing health check-up (group D). An IHA titer >or= 128 was detected in 7.1% of group A, 2.5% of group B, 1.8% of group C, and 0.1% of group D (P < 0.0001). The highest seroprevalence (11.2%) was noted among HIV-infected persons who were men having sex with men (MSM) 30-39 years of age. Compared with persons with gastrointestinal symptoms, the adjusted odds ratio for having high IHA titers among HIV-infected persons was 3.206 (95% confidence interval, 1.433, 7.176; P = 0.005). These findings show that HIV-infected persons, especially MSM 30-39 years of age, are at significantly higher risk of E. histolytica infection.