Use of polymerase chain reaction and quantitative antibody tests in children born to human immunodeficiency virus-1-infected mothers

Time to first positive HIV-1 DNA PCR may differ with antiretroviral regimen in infants infected with non-B subtype HIV-1

OBJECTIVE

To evaluate the association of type and timing of prophylactic maternal and infant antiretroviral regimen with time to first positive HIV-1 DNA PCR test, in nonbreastfed HIV-infected infants, from populations infected predominantly with HIV-1 non-B subtype virus.

DESIGN

Analysis of combined data on nonbreastfed HIV-infected infants from prospective cohorts in Botswana, Thailand, and the United Kingdom (N = 405).

METHODS

Parametric models appropriate for interval-censored outcomes estimated the time to first positive PCR according to maternal or infant antiretroviral regimen category and timing of maternal antiretroviral initiation, with adjustment for covariates.

RESULTS

Maternal antiretroviral regimens included: no antiretrovirals (n = 138), single-nucleoside analog reverse transcriptase inhibitor (n = 165), single-dose nevirapine with zidovudine (n = 66), and combination prophylaxis with 3 or more antiretrovirals [combination antiretroviral therapy (cART), n = 36]. Type of maternal/infant antiretroviral regimen and timing of maternal antiretroviral initiation were each significantly associated with time to first positive PCR (multivariate P < 0.0001). The probability of a positive test with no antiretrovirals compared with the other regimen/timing groups was significantly lower at 1 day after birth, but did not differ significantly after age 14 days. In a subgroup of 143 infants testing negative at birth, infant cART was significantly associated with longer time to first positive test (multivariate P = 0.04).

CONCLUSION

Time to first positive HIV-1 DNA PCR in HIV-1-infected nonbreastfed infants (non-B HIV subtype) may differ according to maternal/infant antiretroviral regimen and may be longer with infant cART, which may have implications for scheduling infant HIV PCR-diagnostic testing and confirming final infant HIV status.

Reduced mortality associated with breast-feeding-acquired HIV infection and breast-feeding among HIV-infected children in Zambia

OBJECTIVES

In developing countries, where mother-to-child transmission of HIV through breast-feeding is common, little is known about the impact of postpartum transmission on child survival. This study assessed whether children infected postpartum have longer survival from time of infection versus those infected during gestation or delivery.

DESIGN

We used a prospective cohort study to analyze data from 213 HIV-infected children enrolled in a breast-feeding intervention trial in Lusaka, Zambia (2001 to 2004).

METHODS

We compared mortality 1 year after HIV infection in children stratified by age of infection: 0 to 3 days (intrauterine [IU] group), 4 to 40 days (intrapartum/early postpartum [IP/EPP] group), and >40 days (postpartum [PP] group).

RESULTS

A total of 61, 71, and 81 children were infected in the IU, IP/EPP, and PP groups, respectively. Children with intrauterine or intrapartum/early postpartum transmission had higher mortality over the first 12 months after infection than children with postpartum transmission (P = 0.001 and P = 0.006, respectively); no differences were detected between children with intrauterine and intrapartum/early postpartum transmission. Nearly 20% of the IU and IP/EPP groups died by 100 days after infection, whereas nearly 10% of the PP group had died by this time. After adjusting for birth weight, maternal CD4 cell count, breast-feeding, and maternal death, children infected postpartum had one quarter the mortality rate (hazard ratio [HR] = 0.27, 95% confidence interval [CI]: 0.15 to 0.50) of those infected in utero. Stopping breast-feeding increased mortality in infected children (HR = 3.1, 95% CI: 1.8 to 5.3).

CONCLUSIONS

This study demonstrates a survival benefit among children infected postpartum versus children infected during pregnancy or delivery and a benefit to increased breast-feeding duration among infected children. Testing children for HIV early may provide a means to allow for earlier intervention.

Semiquantitative human immunodeficiency virus antibody tests in diagnosis of vertical infection

OBJECTIVE

This study evaluated the roles of semiquantitative anti-HIV antibody tests for early diagnosis of vertical HIV-1 infection in infants.

METHODS

The study included 0- to 18-month-old children of HIV-1-infected mothers. They were regularly followed up, and blood was obtained for semiquantitative anti-HIV tests using a particle agglutination (PA) test and a microparticle enzyme immunoassay (MEIA).

RESULTS

One hundred forty-six children of HIV-1-infected mothers, including 104 infected and 42 uninfected infants, were studied. Using anti-HIV titer of < or = 1:100 by PA and optical values of < or = -3 by MEIA for diagnosis of not being infected, approximately 69 and 53% of the uninfected cases at age 7 to 8 months, 76 and 67% at age 9 months and 100% at age 12 months could be diagnosed. By comparison with the diagnosis by qualitative tests the figures were 16%, 8 and 11%, 70 and 74% at the same ages. All asymptomatic HIV-infected cases had persistently high PA titers and MEIA values of at least 1:5000 and 6, respectively, but 7 cases with AIDS-related manifestation at the time of tests had low anti-HIV titers. One severely ill, HIV-infected infant had a transient negative anti-HIV test at the age of 7 months. Two asymptomatic infected children, who had been breast-fed, had transient decrease in anti-HIV titers after the age of 6 months, and transient seroreversion occurred in one. CONCLUSION. Semiquantitative anti-HIV tests between the age of 6 to 12 months were very useful in diagnosis of HIV-1 infection in infants born of HIV-1-infected mothers. Interpretation must be accompanied by information about AIDS-related manifestation and history of breast-feeding.

Timing of human immunodeficiency virus type 1 (HIV-1) transmission from mother to child: bayesian estimation using a mixture

The timing of mother-to-child HIV transmission is not directly observable but influences the infected child's viral and immune status in the neonatal period. A hierarchical model was developed in a Bayesian framework to 'back-calculate' the timing of HIV-1 transmission from mother to child from the virological and immunological kinetics in the infected infant. Joint evolution of viral markers and immune response was modelled as a continuous time Markov process. The modelling of the period from infection to birth was based on a mixture of three distributions taking into account the various mother-to-child transmission pathways: In utero (early or late in gestation) and intrapartum (during the delivery process), integrating the fact that transmission is a continuum during the pregnancy. Gibbs sampling was used to estimate the marginal posterior distributions of the transition intensities between stages of HIV infection and those of the individual times from infection to birth. We applied our model to data on 135 perinatally HIV-1-infected children included in the French Prospective Study on Pediatric HIV infection. The model suggested that transmission occurred late in utero during the last month of pregnancy and that the day of delivery was a particularly critical time in HIV-1 transmission from mother to child. The paper ends with a discussion of model assumptions and a comparison with results obtained using a non-parametric method.

Hospitalization of children born to human immunodeficiency virus-infected women in Europe. The European Collaborative Study

OBJECTIVE

To describe the pattern of inpatient hospital service use in the first 5 years of life of all children born to HIV-infected women in 10 pediatric centers of the European Collaborative Study.

BACKGROUND

Little information is available on the need for hospitalization of children born to HIV-infected women, especially those uninfected, despite the fact that they may be at risk of social deprivation and poor health because of family circumstances.

METHODS

Data on 1189 children enrolled between 1986 and 1997 and followed prospectively since birth according to a standard protocol were analyzed.

RESULTS

This analysis included 151 HIV-infected and 811 uninfected children. One hundred forty (12%) infants had delayed postnatal discharge, mainly for drug withdrawal symptoms and prematurity. Uninfected children had 0.5 admission per 5 child years compared with 2.4 for infected children. From life table analysis, an estimated 48% of infected and 17% of uninfected children will have been admitted by age 12 months. Nearly 60% (3304 of 5604) of the total inpatient days of infected children occurred after AIDS diagnosis. Infected children were 4 times more likely to be hospitalized than uninfected children of the same age, and children with symptomatic mothers were 13 times more likely to be admitted for a nonmedical reason.

CONCLUSIONS

Whereas hospitalization of infected children poses an expected burden on the health care system, the use of such services by uninfected children is largely explained by their social background and provides an argument for better support for families affected by HIV.

Paediatric HIV update

Less than half of the paediatric HIV infections recorded in Australia have resulted from perinatal transmission, but in recent years this has been the predominant mode of infection. There are 136 infants who are known to have been exposed perinatally to HIV in Australia: 49 of these are infected. Caesarean section is thought now not to reduce the risk of perinatal transmission (PNT); rather, the risk increases with duration of membrane rupture and rises rapidly after 4 h of membrane rupture. However, no data exist to show that interventions to expediate delivery after membrane rupture reduce the risk of PNT. Data such as these suggest that the majority of perinatal infections (probably about 60%) occur close to the time of delivery. While the overall risk of PNT for non-breast fed infants is approximately 20-25%, the risk of infection for the infant is considerably increased when there is evidence of increased maternal viral burden. Advanced maternal disease predicts that if the infant is infected there is more likely to be early progression of HIV than is the case for the less frequently infected infants of mothers who are asymptomatic. Bottle feeding may prevent infection of 10% of children exposed perinatally. Use of zidovudine by the mother in the third trimester and i.v. zidovudine during labour, followed by oral zidovudine for the infant for 6 weeks can reduce the PNT rate by two thirds, to about 8%. Approximately 3% of uninfected infants with perinatal HIV exposure may be found to be transiently virus positive but eventually become antibody negative and thus appear to have eliminated the virus. The risk of Pneumocystis carinii pneumonitis (PCP) cannot be predicted on the basis of CD4 count and it is recommended that all children of infected mothers commence PCP prophylaxis around the age of 6 weeks-2 months and continue that therapy until the age of 12 months or until it becomes clear that the infant is uninfected. The cumulative risk of AIDS increases rapidly during the first year of life to about 20%, then more slowly at a rate of about 2 or 3% a year. The shape of this curve reveals the bimodal progression of HIV disease in children. About 15-20% of children rapidly develop a severe immune deficiency, opportunistic infections and, in most cases, encephalopathy. There is a very high morbidity rate in this group of children, most of whom die before the age of 3 or 4 years. In contrast, 80-85% of children only become immunodeficient after a relatively long period, which is similar to or perhaps even longer than that in adults. Recent studies indicate that zidovudine antiviral monotherapy is no longer appropriate. While no clear alternative to monotherapy has emerged most would, wherever possible, commence antiretroviral therapy with a combination of two or three drugs including zidovudine plus didanosine or lamivudine. If a third drug is used it would probably be a protease inhibitor.