Predictors of TB disease in HIV-exposed children from Southern Africa

BACKGROUND: P1041 was a randomised, placebo-controlled isoniazid prophylaxis trial in South Africa. We studied predictors for TB in HIV-exposed children participating in the P1041 trial.METHODS: We included data from entry until Week 108. Predictors considered were type of housing, overcrowding, age, sex, ethnicity, tobacco exposure, weight-for-age percentile Z-score (WAZ), CD4%, viral load (VL), antiretroviral therapy (ART) and number of household smokers.RESULTS: Of 543 HIV-positive (HIV+) and 808 HIV-exposed uninfected (HEU) infants at entry, median age was 96 days (interquartile range: 92-105). Of 1,351 caregivers, 125 (9%) had a smoking history, and 62/1,351 reported current smoking. In 594/1,351 (44%) households, there was at least one smoker. Smoking caregivers consumed 1-5 cigarettes daily. In the HIV+ cohort, significant baseline TB predictors after adjusting covariates were as follows: WAZ (adjusted hazard ratio [aHR] 0.76, P = 0.002) and log10 HIV RNA copies/ml (aHR 1.50, P = 0.009). Higher CD4% (aHR 0.88, P = 0.002) and ART (aHR 0.50, P = 0.006) were protective. In the HEU cohort, smoking exposure was associated with reduced TB-free survival on univariate analysis, but not after adjustment in the multivariate model.CONCLUSION: Low WAZ and high VL were strong predictors of TB disease or death. Rising CD4 percentage and being on ART were protective in the HIV+ cohort.

Use of antiretrovirals in HIV-infected children in a tuberculosis prevention trial: IMPAACT P1041

SETTING

International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) P1041, a tuberculosis (TB) prevention trial conducted among children enrolled from 2004 to 2008 during South Africa's roll-out of combination antiretroviral therapy (ART).

OBJECTIVE

To estimate TB incidence and mortality and the effect of ART.

DESIGN

Children were pre-screened to exclude TB disease and exposure, actively screened 3-monthly for TB exposure and symptoms, and provided post-exposure isoniazid prophylaxis therapy (IPT). TB diagnoses were definite, probable, or possible, and mortality all-cause. Testing was at the 5% significance level.

RESULTS

In 539 children (aged 3-4 months) followed up for a median of 74 weeks (interquartile range [IQR] 48-116), incidence/100 person-years (py) was 10.67 (95%CI 8.47-13.26) for any TB and 2.89 (95%CI 1.85-4.31) for definite/probable TB. Any TB incidence was respectively 9.39, 13.59, and 9.83/100 py before, <180 days after, and 180 days after ART initiation. Adjusted analysis showed a non-significant increase in any TB (HR 1.32, 95%CI 0.71-2.52, P = 0.38) and a significant reduction in mortality (HR 0.39, 95%CI 0.17-0.82, P = 0.017) following ART initiation.

CONCLUSIONS

ART reduced mortality but not TB incidence in human immunodeficiency virus (HIV) infected children in IMPAACT P1041, possibly attributable to active screening for TB exposure and symptoms with post-exposure IPT. Research into this as a strategy for TB prevention in high HIV-TB burden settings may be warranted.

Source case identification in HIV-exposed infants and tuberculosis diagnosis in an isoniazid prevention study

BACKGROUND

Identifying source cases of children exposed to tuberculosis (TB) is challenging. We examined the time-point of obtaining contact information of TB source cases in human immunodeficiency virus (HIV) infected and HIV-exposed uninfected (HEU) children in a randomised, placebo-controlled trial of pre-exposure to isoniazid prophylaxis.

METHODS

A total of 543 HIV-infected and 808 HEU infants without TB exposure aged 3-4 months were enrolled between 2004 and 2008. At 3-monthly follow-up, infants were evaluated for TB and care givers were asked about new TB exposure.

RESULTS

In total, 128 cases of TB disease and 40 deaths were recorded among 19% (105/543) of the HIV-infected and 8% (63/808) of the HEU children; 229 TB contact occasions were reported in 205/1351 (15%) children, of which 83% (189/229) were in the household. Of the 189 household contacts, 108 (53%) underwent microbiological evaluations; 81% (87/108) were positive. HIV-infected and HEU infants had similar frequencies of TB contact: in 48% of infants with definite TB, 58% with probable TB and 43% with possible TB. Of 128 children diagnosed with TB, a TB contact was identified for 59. Of these, 29/59 (49%) were identified at or after the child's TB diagnosis.

CONCLUSION

TB source cases are often identified at or after a child's TB diagnosis. More effort is required for earlier detection.

Loss to follow-up among infants in a study of isoniazid prophylaxis (P1041) in South Africa

OBJECTIVE

To assess risk factors for loss to follow-up (LFU) from the IMPAACT P1041 study, an isoniazid (INH) prophylaxis study conducted in southern Africa.

DESIGN

Infants in two cohorts, human immunodeficiency virus-infected (HIV+) and HIV-exposed but non-infected (HIV-), were randomized to INH or placebo for 96 weeks. LFU was evaluated at week 96.

RESULTS

Of 1351 infants, 12.9% were LFU (10.4% HIV+, 14.7% HIV-); 65% of the HIV+ cohort was asymptomatic. Among HIV+ infants, large household size (>6 vs. <4 members, P = 0.035) and presence of an elder (≥55 years, P = 0.05) were associated with better retention. Although attenuated in adjusted analysis, these associations held among HIV- infants. Among HIV- infants, having a younger mother increased the risk (P = 0.008) and maternal history of TB reduced the risk of LFU, the latter by nearly 70% (P = 0.048 univariate, 0.09 adjusted). LFU was largely due to inability to contact the participant (58% HIV+, 30% HIV-), and inability to attend the clinic and withdrawal of consent (HIV-).

CONCLUSIONS

Household support was an important factor in participant retention, particularly for the non-HIV-infected cohort, as young maternal age was a risk factor for LFU. Retaining study participants from this mobile population can be challenging and may warrant additional support.

Expression of HLA-G1 at the placental interface of HIV-1 infected pregnant women and vertical transmission of HIV

OBJECTIVES

The ability of Human Leucocyte Antigen-G (HLA-G) to inhibit the cytolytic effect to immunocompetent cell types, suggests that HLA-G has an immunomodulatory role. In view of this concept the objective of the study was to assess whether the Major Histocompatibility Complex -coded molecule HLA-G mRNA is a risk factor at the placental barrier in HIV-1 positive pregnant women.

DESIGN

Placental HLA-G1 levels in HIV-1 infected mothers and viral loads in both mothers and their babies were performed on fifty-five participants.

METHODS

Synthesis of complementary deoxyribose nucleic acid (cDNA) was performed using ribose nucleic acid (RNA) extracted from placental tissue samples. Amplification of cDNA using specifically designed primers complementary to the full length HLA-G1 isoform was quantified using real time-polymerase chain reaction (RT-PCR). Viral load assays (Amplicor Version 1.5, Roche Diagnostics) were performed on all plasma samples.

RESULTS

HLA-G1 primers detected the full length isoform HLA-G1 PCR product at 86.5 °C. Logistic regression calculations indicated that the risk of babies becoming infected increased by 1.3 with every 1 unit increase in HLA-G1 expression. Female babies were 3.7 times more likely to become infected than male. There was a positive correlation between mothers' log viral load and transmission of infection to the baby (p = 0.047; 95%CI 1.029-11.499).

CONCLUSION

Maternal viral load was a strong predictor of viral transmission. Placental HLA-G1 expression was up-regulated 3.95 times more in placentas of HIV-1 infected mothers with infected babies when compared to uninfected babies.

The impact of human immunodeficency virus 1 on largyngeal airway obstruction in children

Children with laryngeal airway obstruction (LAO) require admission to the intensive care unit (ICU). The unresolved ethical dilemma of ICU access for HIV infected children in resource poor settings requires further scientific data to help guide triaging. Of 38 children with LAO, 19 had HIV infection. The mortality, need for supportive management, duration of intubation, intermittent positive pressure ventilation, and ICU and hospitalisation stay were similar in the HIV infected group compared to the HIV uninfected group. Episodes of laryngotracheobronchitis were equally distributed between both groups (31.6% v 31.3%), while oropharyngeal/laryngeal candidiasis (26.3%), tuberculosis (15.8%), and benign lymphoid hyperplasia (15.8%) were commonly seen in the HIV infected group.

Growth in early childhood in a cohort of children born to HIV-1-infected women from Durban, South Africa

This study describes growth in a cohort of black South African children born to HIV-1-infected women in Durban. Children born to HIV-1-seropositive women were followed up from birth to early childhood. At birth and at each visit, growth parameters were measured. Mean Z-scores were calculated for weight-for-length, weight-for-age and length-for-age and, if they were low, the children were regarded as wasted, malnourished or stunted, respectively. At the end of the study, there were 48 infected and 93 uninfected children. There were no significant differences between the two groups at birth. Thereafter, the infected group was found to have early and sustained low mean Z-scores for length-for-age and weight-for-age but not for weight-for-length. The means reached significance at ages 3, 6 and 12 months for length and at 3, 6 and 9 months for weight. Infected children who died early had more severe stunting, wasting and malnutrition than infected children who survived. Infected children born to HIV-positive women have early and sustained stunting and are malnourished but not wasted. Children with rapidly progressive disease have both stunting and wasting and are more severely affected. Early nutritional intervention might help prevent early progression or death in HIV-infected children, particularly in developing countries without access to anti-retroviral therapy in state hospitals.

Mortality in a cohort of children born to HIV-1 infected women from Durban, South Africa

OBJECTIVES

To describe mortality in a cohort of infants with vertically transmitted HIV-1 infection.

PATIENTS AND METHODS

Children of HIV-1 infected women were followed up from birth and a record was made at each visit of growth, development and all illnesses. Details surrounding death were obtained from hospital records.

RESULTS

The final cohort comprised 48 infected and 93 uninfected children; there were 25 deaths, 17 of which (35%) were regarded as being HIV-related. The mean age at death of HIV-related cases was 10.1 months (range 1-48 months), with 83% of HIV-related deaths occurring before the age of 10 months. The commonest diagnoses at the time of death were diarrhoea, pneumonia, failure to thrive and severe thrush. These findings, together with neurological abnormalities, often presaged rapid deterioration and death.

CONCLUSIONS

Mortality among children with vertically acquired HIV infection is high in the first year of life. Death in these subjects was due to the common causes of morbidity and mortality among all children in developing countries. A combination of diarrhoea, pneumonia, failure to thrive, and neurological abnormalities should alert one to the possibility of rapidly progressive disease and death.

The early natural history of vertically transmitted HIV-1 infection in African children from Durban, South Africa

Forty-eight children with vertically transmitted HIV-1 infection and 93 uninfected infants were followed up at regular intervals from birth for a mean of 26 months. They were examined physically, growth and development were assessed and illnesses recorded. Seventy per cent of infected infants were symptomatic by 6 months. Relative risks in the infected infants were highest for lymphadenopathy (4.56; CI 2.7-7.7), failure to thrive (4.48; 2.57-7.81), and neurological abnormalities (3.32; 1.9-5.58). The most frequent findings were diarrhoea (78%), pneumonia (76%) and lymphadenopathy (70%). Thrush and pneumonia occurred early but declined over time, whereas diarrhoea and neurological abnormalities occurred later and increased in frequency. A diagnosis of AIDS was made in 44% of infected infants by 12 months of age. Mortality in infected infants was 35.4%, and 76% of deaths occurred within the 1st year. About two-thirds of HIV-infected infants survived into early childhood. In South African children with vertically acquired HIV-1 infection the onset of disease is early and deterioration to AIDS and death are rapid. Infected infants can be easily recognized clinically, the majority by 6 months of age.

Breastfeeding by HIV-1-infected women and outcome in their infants: a cohort study from Durban, South Africa

BACKGROUND

Women in developing countries have the difficult choice of balancing the risk of transmitting HIV through breast milk against the substantial benefits of breastfeeding. It is not known, however, whether the benefits of breastfeeding are the same when the mother is HIV-infected. Therefore, we examined the impact of breastfeeding on infections, growth and mortality in the infants of HIV-1-infected women.

METHODS

Infants of HIV-1-positive women were followed from birth and at each visit they were examined, growth parameters were recorded and notes were made of feeding method, and of current and interim illnesses.

RESULTS

Of the 43 HIV-infected and 90 non-infected infants for whom feeding data were available, 36 infants (27%) were exclusively breastfed, 76 (57%) received mixed feeding, and 21 (16%) received formula only. The HIV transmission rate was 39% in those exclusively breastfed, 24% in those fed exclusively on formula and 32% in those receiving mixed feeding [relative risk (RR), 7.39; 95% confidence interval (CI), 1.67-32.6 between the exclusive breast and formula only groups]. There was a stepwise increase in the transmission rate with duration of exclusive breastfeeding of 1, 2 and 3 months (45%, 64%, and 75%, respectively). Of the infected infants, seven (50%) exclusively breastfed, 13 (51%) of those on mixed feeds and none on formula only developed AIDS; exclusively breastfed infants had a slower rate of progression to AIDS (mean age, 7.5 months versus 5.0 months, P = 0.2242) than those on mixed feeds. Mortality (which occurred in the infected infants only) was 19% in the exclusively breastfed infants; 13% in those on mixed feeds and 0% in those exclusively formula-fed. The frequency of failure to thrive and episodes of diarrhoea and pneumonia were not significantly different between the three groups in both the infected and non-infected infants.

CONCLUSIONS

Exclusive breastfeeding by HIV-infected women does not appear to protect their infants against common childhood illnesses and failure to thrive, nor does it significantly delay progression to AIDS. The implication of the trend towards differential mortality rates according to feeding groups is uncertain and requires further investigation.

Determinants of mother-to-child transmission of human immunodeficiency virus type 1 infection in a cohort from Durban, South Africa

OBJECTIVES

To determine the vertical transmission rate of HIV-1 infection and to assess the influence of maternal risk factors on transmission in infants born to HIV-1-infected black women in Durban.

DESIGN

A prospective, hospital-based cohort study conducted at King Edward VIII hospital, Durban. HIV-1-seropositive women were enrolled into the study, and their infants were followed up at regular intervals from birth to early childhood. The infection status of the children was classified and the transmission rate was computed according to the recommendations of the workshop held in Ghent, Belgium (1992).

RESULTS

The final cohort of 181 infants were classified as 48 infected, 93 not infected and 40 indeterminate. Clearance of maternal antibodies was achieved by 12 months of age in virtually all infants who became seronegative. The intermediate transmission rate was 34% (95% confidence interval, 26 to 42). Deliveries by cesarean section had significantly lower transmission (relative risk, 0.46; 95% confidence interval 0.23 to 0.91). Women with lower hemoglobin concentrations during pregnancy (< 10 g/dl) had an increased risk of transmission (relative risk, 1.99; 95% confidence interval, 1.18 to 3.34). Advanced maternal age, multiparity, positive syphilis serology, duration of ruptured membranes, preterm delivery and breast-feeding were not associated with an increased risk of transmission.

CONCLUSIONS

This study, the first from South Africa, has confirmed that the rate of vertical transmission of HIV-1 is as high as that reported from most African cohorts. Cesarean sections were protective against transmission, whereas low hemoglobin values values were associated with an increased risk of transmission. Twelve months could be used as the cutoff age for teh diagnosis of vertical infection using antibody tests.

Cesarean deliveries and maternal-infant HIV transmission: results from a prospective study in South Africa

Data from a prospective study undertaken at an urban hospital in Durban, South Africa, were used to investigate associations between maternal-infant HIV transmission, mode of delivery, and specific circumstances of cesarean deliveries. A total of 141 children of HIV-infected women were followed until the children were 15 months of age to determine their HIV status. supplementary data were collected from obstetric records, masked to the HIV status of the children. In this African and predominantly breast-fed population, infants delivered vaginally were more likely to be infected (39.8% infected) than were infants delivered by cesarean section [22.9% infected; odds ratio (OR), 0.45; 95% confidence interval (CI), 0.20-0.99]. There were no significant differences between cesarean deliveries undertaken following prior rupture of membranes and those undertaken with membranes intact, but numbers for this comparison were small. Singleton cesarean deliveries without concurrent obstetric complications had lower rates of transmission than did vaginal deliveries (OR, 0.20; 95% CI, 0.04-0.94). These results suggest that certain intrapartum events may modify the risk of HIV transmission and highlight the importance of collecting more detailed intrapartum information in order to clarify the route by which mode of delivery may be associated with maternal-infant HIV transmission.