Prevalence of genotypic drug resistance among a cohort of HIV-infected newborns

Prevalence and effect of pre-treatment drug resistance on the virological response to antiretroviral treatment initiated in HIV-infected children - a EuroCoord-CHAIN-EPPICC joint project

Background

Few studies have evaluated the impact of pre-treatment drug resistance (PDR) on response to combination antiretroviral treatment (cART) in children. The objective of this joint EuroCoord-CHAIN-EPPICC/PENTA project was to assess the prevalence of PDR mutations and their association with virological outcome in the first year of cART in children.

Methods

HIV-infected children <18 years initiating cART between 1998 and 2008 were included if having at least one genotypic resistance test prior to cART initiation. We used the World Health Organization 2009 resistance mutation list and Stanford algorithm to infer resistance to prescribed drugs. Time to virological failure (VF) was defined as the first of two consecutive HIV-RNA > 500 copies/mL after 6 months cART and was assessed by Cox proportional hazards models. All models were adjusted for baseline demographic, clinical, immunology and virology characteristics and calendar period of cART start and initial cART regimen.

Results

Of 476 children, 88 % were vertically infected. At cART initiation, median (interquartile range) age was 6.6 years (2.1–10.1), CD4 cell count 297 cells/mm³ (98–639), and HIV-RNA 5.2 log₁₀copies/mL (4.7–5.7). Of 37 children (7.8 %, 95 % confidence interval (CI), 5.5–10.6) harboring a virus with ≥1 PDR mutations, 30 children had a virus resistant to ≥1 of the prescribed drugs. Overall, the cumulative Kaplan-Meier estimate for virological failure was 19.8 % (95 %CI, 16.4–23.9). Cumulative risk for VF tended to be higher among children harboring a virus with PDR and resistant to ≥1 drug prescribed than among those receiving fully active cART: 32.1 % (17.2–54.8) versus 19.4 % (15.9–23.6) (P = 0.095). In multivariable analysis, age was associated with a higher risk of VF with a 12 % reduced risk per additional year (HR 0.88; 95 %CI, 0.82–0.95; P < 0.001).

Conclusions

PDR was not significantly associated with a higher risk of VF in children in the first year of cART. The risk of VF decreased by 12 % per additional year at treatment initiation which may be due to fading of PDR mutations over time. Lack of appropriate formulations, in particular for the younger age group, may be an important determinant of virological failure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1968-2) contains supplementary material, which is available to authorized users.

The new face of the pediatric HIV epidemic in Western countries: demographic characteristics, morbidity and mortality of the pediatric HIV-infected population

The natural history of the pediatric HIV epidemic has changed since the introduction of strategies for the prevention of mother-to-child transmission and the implementation of highly active antiretroviral therapy. The demographic characteristics of the pediatric HIV-infected population and the incidence and pattern of HIV-related morbidity, as well as mortality rates, have been remarkably modified. This report gives an overview on the main changes that occurred in Western countries.

Antiretroviral treatment failure, drug resistance, and subtype diversity in the only pediatric HIV clinic in Rhode Island

BACKGROUND

Drug resistance development in the human immunodeficiency virus (HIV)-infected pediatric population in the United States can impact long-term antiretroviral therapy (ART) efficacy. Limited formularies and adherence constraints in children jeopardize lifelong-needed ART.

METHODS

We examined treatment failure, drug resistance, and their correlates in ART-naive and ART-experienced children attending the pediatric HIV clinic in Rhode Island between 1991 and 2012. Pol sequences were obtained for phylogenetic, subtype, and resistance analyses. Associations between selected covariates and virologic failure and resistance were evaluated using generalized additive models and Fisher exact tests.

RESULTS

Data were available for all 56 clinic-attending children. At diagnosis, 33% were aged <1 year, 31% aged 1-4 years, and 37% aged ≥ 5 years; 54% were male, 73% black or Hispanic, 55% US-born, 20% refugees, and 64% perinatally infected. Of 44 ART-experienced children, 57% had virologic failure, most never virologically suppressed. Failure was associated with missed appointments (P = .05) and missed doses (P < .01). Of 40 children with available genotypes, 35% were infected with non-B subtypes; 6% of ART-naive children had resistance; and 73% of ART-experienced children had ≥ 1 major mutation: (16% conferring triple-class, 47% dual-class, and 37% single-class resistance). An epidemiologically confirmed resistance transmission from a perinatally infected teenage male to a newly infected teenage female was demonstrated.

CONCLUSIONS

We report high HIV type 1 diversity, extensive drug resistance among ART-experienced children, and horizontal transmission of resistance in the Rh ode Island pediatric HIV clinic. As HIV-infected children mature into adulthood, close monitoring of ART, adherence, and diagnosis disclosure are essential to optimize patient care.

Drug resistance in the HIV-1-infected paediatric population worldwide: a systematic review

BACKGROUND

Drug resistance monitoring of the paediatric HIV-1-infected population is required to optimize treatment success and preserve future treatment options.

OBJECTIVES

To explore the current knowledge of HIV drug resistance (HIVDR) in naive and pretreated HIV-1-infected paediatric populations across diverse settings and sampling time periods.

METHODS

PubMed database screened until May 2013. We selected publications including data on transmitted (TDR) and acquired drug resistance mutation (DRM) rates and/or pol sequences for HIVDR testing in paediatric patients. We recorded the children's country, age, study period, number of children with pol sequences, presence or absence of antiretroviral treatment (ART) at sampling time, viral region sequenced, HIVDR rate to the three main drug classes (single, double or triple), the considered resistance mutation list and performed assay, specimen type, HIV-1 variants and subtyping methodology when available.

RESULTS

Forty-one selected studies showed HIVDR data from 2538 paediatric HIV-1-infected patients (558 naive and 1980 pretreated) from 30 countries in Africa (11), Asia (6), America (10) and Europe (3). Both TDR and DRM prevalence were reported in 9 studies, only TDR in 6 and only DRM in 26. HIVDR prevalence varied across countries and periods. Most studies used in-house resistance assays using plasma or infected cells. HIV-1 non-B variants were prevalent in 18 paediatric cohorts of the 24 countries with reported subtypes. Only five countries (Uganda, Spain, the UK, Brazil and Thailand) presented resistance data in ≥200 patients.

CONCLUSIONS

Systematic and periodic studies among infected children are crucial to design a more suitable first- or second-line therapy.

[Consensus statement on monitoring of HIV: pregnancy, birth, and prevention of mother-to-child transmission]

OBJECTIVE

The main objective in the management of HIV-infected pregnant women is prevention of mother-to-child transmission; therefore, it is essential to provide universal antiretroviral treatment, regardless of CD4 count. All pregnant women must receive adequate information and undergo HIV serology testing at the first visit.

METHODS

We assembled a panel of experts appointed by the Secretariat of the National AIDS Plan (SPNS) and the other participating Scientific Societies, which included internal medicine physicians with expertise in the field of HIV infection, gynecologists, pediatricians and psychologists. Four panel members acted as coordinators. Scientific information was reviewed in publications and conference reports up to November 2012. In keeping with the criteria of the Infectious Diseases Society of America, 2levels of evidence were applied to support the proposed recommendations: the strength of the recommendation according to expert opinion (A, B, C), and the level of empirical evidence (I, II, III). This approach has already been used in previous documents from SPNS.

RESULTS AND CONCLUSIONS

The aim of this paper was to review current scientific knowledge, and, accordingly, develop a set of recommendations regarding antiretroviral therapy (ART), regarding the health of the mother, and from the perspective of minimizing mother-to-child transmission (MTCT), also taking into account the rest of the health care of pregnant women with HIV infection. We also discuss and evaluate other strategies to reduce the MTCT (elective Cesarean, child's treatment…), and different aspects of the topic (ARV regimens, their toxicity, monitoring during pregnancy and postpartum, etc.).

HIV-1 drug resistance prevalence, drug susceptibility and variant characterization in the Jacobi Medical Center paediatric cohort, Bronx, NY, USA

OBJECTIVES

With the advent of combined antiretroviral therapy (cART), perinatally HIV-infected children are surviving into adolescence and beyond. However, drug resistance mutations (DRMs) compromise viral control, affecting the long-term effectiveness of ART. The aims of this study were to detect and identify DRMs in a HIV-1 infected paediatric cohort.

METHODS

Paired plasma and dried blood spots (DBSs) specimens were obtained from HIV-1 perinatally infected patients attending the Jacobi Medical Center, New York, USA. Clinical, virological and immunological data for these patients were analysed. HIV-1 pol sequences were generated from samples to identify DRMs according to the International AIDS Society (IAS) 2011 list.

RESULTS

Forty-seven perinatally infected patients were selected, with a median age of 17.7 years, of whom 97.4% were carrying subtype B. They had a mean viral load of 3143 HIV-1 RNA copies/mL and a mean CD4 count of 486 cells/μL at the time of sampling. Nineteen patients (40.4%) had achieved undetectable viraemia (< 50 copies/mL) and 40.5% had a CD4 count of > 500 cells/μL. Most of the patients (97.9%) had received cART, including protease inhibitor (PI)-based regimens in 59.6% of cases. The DRM prevalence was 54.1, 27.6 and 27.0% for nucleoside reverse transcriptase inhibitors (NRTIs), PIs and nonnucleoside reverse transcriptase inhibitors (NNRTIs), respectively. Almost two-thirds (64.9%) of the patients harboured DRMs to at least one drug class and 5.4% were triple resistant. The mean nucleotide similarity between plasma and DBS sequences was 97.9%. Identical DRM profiles were present in 60% of plasma-DBS paired sequences. A total of 30 DRMs were detected in plasma and 26 in DBSs, with 23 present in both.

CONCLUSIONS

Although more perinatally HIV-1-infected children are reaching adulthood as a result of advances in cART, our study cohort presented a high prevalence of resistant viruses, especially viruses resistant to NRTIs. DBS specimens can be used for DRM detection.

Trends in drug resistance prevalence in HIV-1-infected children in Madrid: 1993 to 2010 analysis

BACKGROUND

Drug resistance mutations compromise antiretroviral treatment (ART) effectiveness in HIV-1-infected children. Trends in drug resistance prevalence have not been previously evaluated in HIV-infected children in Spain.

METHODS

HIV-1 variants, drug resistance prevalence dynamics and drug susceptibility were analyzed from 1993 to 2010 in HIV-infected children with available pol sequence, sample or drug resistance profile. HIV-1 variants were characterized by phylogenetic analysis. Resistance mutations in pretreated and naive patients were identified according to International AIDS Society-2010 and the World Health Organization list, respectively.

RESULTS

In 232 patients, genotypic resistance profiles (n = 11) or pol sequences (n = 128) were recovered or newly generated from infected samples (n = 93). Patients were mainly in care at pediatric units (63%), were mostly Europeans (84%), with moderate AIDS symptoms (65%), on ART (91%) and infected by HIV-1 subtype B (89%). Transmitted major drug resistance mutations were selected in 6 (13.6%) of the 44 ART-naive children: 4.8%, 9.3% and 11.6%, for protease inhibitors, nucleoside reverse transcriptase inhibitors and nonnucleoside reverse transcriptase inhibitors, respectively. Overall resistance prevalence was higher (71.8%) among ART-exposed children: 39.9%, 66.5% and 35.3% for protease inhibitors, nucleoside reverse transcriptase inhibitors and nonnucleoside reverse transcriptase inhibitors, respectively. Resistance prevalence among ART-exposed children was higher in 2009 to 2010 relative to 1993 to 1999 for nonnucleoside reverse transcriptase inhibitors (42% versus 6%; P = 0.006), protease inhibitors (39% versus 13%; P = 0.004) and nucleoside reverse transcriptase inhibitors (63% versus 44%; P = NS). Susceptibility to each drug in resistant viruses was predicted. The rate of non-B infections increased in the last years, mainly caused by recombinant viruses.

CONCLUSIONS

The increasing resistance prevalence among the HIV-infected pediatric population in Spain highlights the importance of specific drug resistance and drug susceptibility surveillance in long-term pretreated children to optimize treatment regimens.

A framework for elimination of perinatal transmission of HIV in the United States

The availability of effective interventions to prevent mother-to-child HIV transmission and the significant reduction in the number of HIV-infected infants in the United States have led to the concept that elimination of mother-to-child HIV transmission (EMCT) is possible. Goals for elimination are presented. We also present a framework by which elimination efforts can be coordinated, beginning with comprehensive reproductive health care (including HIV testing) and real-time case-finding of pregnancies in HIV-infected women, and conducted through the following: facilitation of comprehensive clinical care and social services for women and infants; case review and community action; allowing continuous quality research in prevention and long-term follow-up of HIV-exposed infants; and thorough data reporting for HIV surveillance and EMCT evaluation. It is emphasized that EMCT will not be a one-time accomplishment but, rather, will require sustained effort as long as there are new HIV infections in women of childbearing age.

Short communication: high prevalence of drug resistance in HIV type 1-infected children born in Honduras and Belize 2001 to 2004

Antiretroviral therapy has had a great impact on the prevention of mother-to-child transmission (MTCT) of HIV-1. However, development of drug resistance, which could be subsequently transmitted to the child, is a major concern. In Honduras and Belize the prevalence of drug resistance among HIV-1-infected children remains unknown. A total of 95 dried blood spot samples was obtained from HIV-1-infected, untreated children in Honduras and Belize born during 2001 to 2004, when preventive antiretroviral therapy was often suboptimal and consisted of monotherapy with nevirapine or zidovudine. Partial HIV-1 pol gene sequences were successfully obtained from 66 children (Honduras n=55; Belize n=11). Mutations associated with drug resistance were detected in 13% of the Honduran and 27% of the Belizean children. Most of the mutations detected in Honduras (43%) and all mutations detected in Belize were associated with resistance to nonnucleoside reverse transcriptase inhibitors, which was expected from the wide use of nevirapine to prevent MTCT during the study period. In addition, although several mothers reported that they had not received antiretroviral therapy, mutations associated with resistance to nucleoside reverse transcriptase inhibitors and protease inhibitors were found in Honduras. This suggests prior and unreported use of these drugs, or that these women had been infected with resistant virus. The present study demonstrates, for the first time, the presence of drug resistance-associated mutations in HIV-1-infected Honduran and Belizean children.

The clinical care of the HIV-1-infected infant

Despite well-established strategies to decrease the mother-to-child transmission of HIV-1, new perinatal infections continue to occur globally, reflecting marked disparities in access to health care. Once HIV-1 infection has been established in an infant, the combination of early initiation of antiretroviral therapy and prophylaxis against Pneumocystis jiroveci pneumonia is paramount to reducing disease progression. This article reviews the recommendations and evidence for the treatment of HIV-1-infected infants.

HIV drug resistance and mother-to-child transmission of HIV

This article covers HIV drug resistance among pregnant women and the implications of transmission of resistant HIV to the infant. Resistance to antiretroviral drugs may be acquired or can emerge while HIV-infected pregnant women are on antiretroviral therapy, either before or during pregnancy. Resistance to antiretroviral drugs among HIV-infected infants may be acquired from the mother in utero or during the intrapartum period. Resistance may also emerge from exposure to antiretroviral drugs given to the infant for prophylaxis against HIV transmission. In settings where breastfeeding is practiced, ongoing transmission of HIV from breastfeeding may lead to transmission of resistant HIV from the mother. If the mother is taking antiretroviral drugs while breastfeeding, resistance to antiretroviral drugs may emerge in an HIV-infected infant from ingestion of antiretroviral drugs via breast milk. The magnitude and implications of antiretroviral resistance among HIV-infected pregnant women and HIV-infected infants are summarized.

Perinatal acquisition of drug-resistant HIV-1 infection: mechanisms and long-term outcome

Background

Primary-HIV-1-infection in newborns that occurs under antiretroviral prophylaxis that is a high risk of drug-resistance acquisition. We examine the frequency and the mechanisms of resistance acquisition at the time of infection in newborns.

Patients and Methods

We studied HIV-1-infected infants born between 01 January 1997 and 31 December 2004 and enrolled in the ANRS-EPF cohort. HIV-1-RNA and HIV-1-DNA samples obtained perinatally from the newborn and mother were subjected to population-based and clonal analyses of drug resistance. If positive, serial samples were obtained from the child for resistance testing.

Results

Ninety-two HIV-1-infected infants were born during the study period. Samples were obtained from 32 mother-child pairs and from another 28 newborns. Drug resistance was detected in 12 newborns (20%): drug resistance to nucleoside reverse transcriptase inhibitors was seen in 10 cases, non-nucleoside reverse transcriptase inhibitors in two cases, and protease inhibitors in one case. For 9 children, the detection of the same resistance mutations in mothers' samples (6 among 10 available) and in newborn lymphocytes (6/8) suggests that the newborn was initially infected by a drug-resistant strain. Resistance variants were either transmitted from mother-to-child or selected during subsequent temporal exposure under suboptimal perinatal prophylaxis. Follow-up studies of the infants showed that the resistance pattern remained stable over time, regardless of antiretroviral therapy, suggesting the early cellular archiving of resistant viruses. The absence of resistance in the mother of the other three children (3/10) and neonatal lymphocytes (2/8) suggests that the newborns were infected by a wild-type strain without long-term persistence of resistance when suboptimal prophylaxis was stopped.

Conclusion

This study confirms the importance of early resistance genotyping of HIV-1-infected newborns. In most cases (75%), drug resistance was archived in the cellular reservoir and persisted during infancy, with or without antiretroviral treatment. This finding stresses the need for effective antiretroviral treatment of pregnant women.

Vertical transmission of multidrug-resistant Q151M human immunodeficiency virus type 1 strains

We report the first case of mother-to-child transmission of human immunodeficiency virus type 1 strains harboring multiple mutations including the Q151M multinucleoside reverse transcriptase inhibitor resistance mutation. Sustained virologic success was obtained in the infant with postnatal antiretroviral therapy optimized according to genotypic drug resistance testing and therapeutic drug monitoring.

High frequency of primary mutations associated with antiretroviral drug resistance in recently diagnosed HIV-infected children

Introduction

The aim of our study was to analyse the frequency of primary mutations associated with HIV drug resistance in a population of children born to HIV-infected mothers.

Design

A prospective study included newly HIV-diagnosed children treated at two public paediatric hospitals.

Patients and methods

Clinical and antiretroviral therapy (ART) data were collected in mother-child pairs. HIV-1 subtyping and ART resistance mutations were assayed in children by sequencing a region of HIV pol gene.

Results: A total of 67 children were enrolled

22 less than 12 months of age, 20 between 1 and 5 years and 25 between 6 and 14 years. Six (9.0%) children had viral strains with at least one primary mutation associated with resistance to reverse transcriptase and protease inhibitors. A significantly ( P=0.019) higher frequency of resistance (22.7%, n=5/22) was found among children aged <12 months. Fourteen children (20.9%) had a subtype B HIV-1 strain and 53 (79.1%) had an inter-subtype B/F recombinant variant.

Discussion

A high percentage of recently diagnosed infants were found to carry primary ART resistance mutations. Limited options for ART of HIV-infected children might lead to increased HIV-associated morbidity and mortality. Thus, consideration should be given to mandatory screening for primary ART resistance before initiating therapy for infants aged <12 months in countries where HIV mother-to-child transmission is still present, such as in Argentina. This will allow for the rationalized and individualized use of drugs and will contribute to the increased cost-effectiveness of local health systems.

Care and management of the infant of the HIV-1-infected mother

Mother-to-child transmission of the human immunodeficiency virus continues to be a major global health problem. The pediatric HIV-1 epidemic is fueled by HIV-1 infection in women of childbearing age with vertical transmission in utero or at the time of birth. In resource-rich countries, the birth of an infected child is a sentinel health event signaling a chain of missed opportunities and barriers to prevention. Because the fate and ultimate HIV-infection status of the baby is inextricably linked to the infection status of the mother and her general state of well-being, we provide in this review: 1) background and state-of-the-art management guidelines for optimum maternal care; 2) strategies to minimize the risk of vertical transmission of HIV; and 3) recommendations for managing infants born to HIV-infected women. These are discussed under four case scenarios that obstetric and pediatric providers frequently encounter in their practices.

La résistance du VIH-1 aux antirétroviraux chez les enfants infectés : du nouveau-né à l'adolescent

Limit of antiretroviral treatment success is the emergence of drug-resistant virus. As reported in adult population, prevalence of resistance was high in treated HIV-infected children with detectable HIV viral load. Resistance increased with number of prior antiretroviral treatments, particularly with protease inhibitors. Adolescent boys seem at greater risk to harbor multi-classes resistant virus. In HIV-infected newborns, prevalence of resistance was 20%. Most of resistance mutations detected were in accord to perinatal antiretroviral exposition. Principal mechanism of resistance acquisition in newborns was transmission of resistant viruses from mother to child with early archive in cellular reservoir and long term persistence with or without treatment. Consequences of long term therapeutic strategies in children are major.

Prevalence of drug-resistance mutations and non-subtype B strains among HIV-infected infants from New York State

Prevalence studies indicate that transmission of drug-resistant HIV has been rising in the adult population, but data from the perinatally infected pediatric population are limited. In this retrospective study, we sequenced the pol region of HIV from perinatally infected infants diagnosed in New York State in 2001-2002. Analyses of drug resistance, subtype diversity, and perinatal antiretroviral exposure were conducted, and the results were compared with those from a previous study of HIV-infected infants identified in 1998-1999. Eight of 42 infants (19.1%) had provirus carrying at least 1 drug-resistance mutation, an increase of 58% over the 1998-1999 results. Mutations conferring resistance to nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors were detected in 7.1%, 11.9%, and 2.4% of specimens, respectively. Consistent with previous results, perinatal antiretroviral exposure was not associated with drug resistance (P = 0.70). Phylogenetic analysis indicated that 16.7% of infants were infected with a non-subtype B strain of HIV. It seems that drug-resistant and non-subtype B strains of HIV are becoming increasingly common in the perinatally infected population. Our results highlight the value of resistance testing for all HIV-infected infants upon diagnosis and the need to consider subtype diversity in diagnostic and treatment strategies.

Pharmacokinetics of didanosine and drug resistance mutations in infants exposed to zidovudine during gestation or postnatally and treated with didanosine or zidovudine in the first three months of life

BACKGROUND

There are limited numbers of drugs that are available in formulations that are appropriate for neonates and few studies assessing resistance among infants born to human immunodeficiency virus (HIV)-infected women.

METHODS

Pharmacokinetics and tolerance of didanosine (ddI) were determined for infants < or =120 days of age. Infants received at least 24 hours of zidovudine (ZDV) treatment, followed by a single ddI dose and pharmacokinetic sampling. The target area under the concentration-time curve (AUC) was between 2.5 and 5.0 microM . hour. Toxicity and drug resistance mutations were assessed at baseline and follow-up times.

RESULTS

The initial ddI pharmacokinetic dosing of 50 mg/m for infants >28 days of age achieved a median AUC0-infinity of 2.8 microM . hour. For infants < or =28 days of age, the target AUC was achieved after dose escalation from 25 mg/m (median AUC0-infinity, 1.4 microM . hour) to 50 mg/m (median AUC0-infinity, 5.40 microM . hour). At baseline, 25% of infected infants had drug resistance mutations (9 of 44 to ZDV and 2 of 44 to ddI). Resistance mutations were present for 29% of infants (5 of 17 infants) with in utero ZDV exposure and 25% (8 of 32 infants) with prior ZDV treatment. The most common ZDV mutation noted at baseline was the T215Y/F (n = 7) mutation; 2 of these infants also had the M41L mutation, which is associated with high level ZDV resistance. No prior exposure was noted for the 2 infants with ddI resistance, which indicates possible perinatal transmission of ddI-resistant virus to these infants.

CONCLUSIONS

A dose of 50 mg/m is the appropriate ddI dose for infants <120 days of age and is a safe treatment for newborns when used in combination with ZDV. Genotypic resistance occurs frequently among infected infants exposed to ZDV during gestation or postnatally, which suggests that resistance testing should be considered for infants with newly diagnosed HIV infection.

Recomendaciones CEVIHP/SEIP/AEP/PNS respecto al tratamiento antirretroviral en niños y adolescentes infectados por el VIH

OBJECTIVE

To update antiretroviral recommendations in antiretroviral therapy (ART) in HIV-infected children and adolescents.

METHODS

Theses guidelines have been formulated by a panel of members of the Plan Nacional sobre el SIDA (PNS) and the Asociacion Espanola de Pediatria (AEP) by reviewing the current available evidence of efficacy, safety, and pharmacokinetics in pediatric studies. Three levels of evidence have been defined according to the source of data: Level A: randomized and controlled studies; Level B: Cohort and case-control studies; Level C: Descriptive studies and experts' opinion.

RESULTS

When to start ART should be made on an individual basis, discussed with the family, considering the risk of progression according to age, CD4 and viral load, the ART-related complications and adherence. The ART goal is to reach a maximum and durable viral suppression. This is not always possible, even with clinical and immunologic improvement. The difficulties of permanent adherence and side-effects are resulting in a more conservative trend to initiate ART, and to less toxic and simpler strategies. Currently, combinations of at least three drugs are of first choice both in acute and chronic infection. They must include 2 NA 1 1 NN or 2 NA 1 1 PI. ART is recommended in all symptomatic patients and, with few exceptions, in all infants in the first year of life. Older asymptomatic children should start ART according to CD4 count, especially CD4 percentage, that vary with age. Despite potent salvage therapies, it is common not to reach viral undetectability. Therapeutical options when ART fails are scarce due to cross-resistance. The cause of failure must be identified. Occasionally, there exists clinical and/or immunological progression, and a change of therapy with at least two new drugs still active for the patient, is warranted with the aim of increasing the CD4 count to a lower level of risk. Toxicity and adherence must be regularly monitored. Some aspects about post exposure prophylaxis and coinfection with HCV or HBV are discussed.

CONCLUSIONS

A higher level of evidence with regard to ART effectiveness and toxicity in pediatrics is currently available, leading to a more conservative and individualized approach. Clinical symptoms and CD4 count are the main determinants to start and change ART.

Pharmacotherapy of perinatal HIV

Continued spread of HIV infection among women has led to the use of antiretrovirals in pregnant women and their newborns. Regional strategies to prevent mother-to-child transmission are evolving. Altered drug disposition during pregnancy may require altered dosing or 'boosted' therapies to avoid treatment failure. Maturing drug elimination pathways in newborns must also be considered for effective therapy. Potential teratogenic effects and increased sensitivity to antiretroviral toxicities might be encountered in this population. Use of highly active antiretroviral therapy (HAART) to suppress viral replication combined with formula feeding can reduce the rate of mother-to-child HIV transmission to less than 2%. In resource-limited settings, less intensive regimens including zidovudine, lamivudine and nevirapine still substantially reduce mother-to-child transmission. Although difficult to perform, clinical trials to determine the safety, pharmacokinetics and optimal dosing of antiretroviral in pregnant women and their newborns are urgently needed.

The antiretroviral rollout and drug-resistant HIV in Africa: insights from empirical data and theoretical models

The U.S. Government has pledged to spend $15 billion in Africa and the Caribbean on AIDS. A central focus of this plan is to provide antiretroviral treatment (ART) to millions. Here, we evaluate whether the plan to rollout ART in Africa is likely to generate an epidemic of drug-resistant strains of HIV. We review what has occurred as a result of high usage of ART in developed countries in terms of changes in risky behavior, and the emergence and transmission of drug-resistant HIV. We also review how mathematical models have been used to predict the evolution of drug-resistant HIV epidemics. We then show how models can be used to predict the likely impact of the ART rollout on the evolution of drug-resistant HIV in Africa. At currently planned levels of treatment coverage, we predict that (over the next decade) in Africa: (i) the impact of ART on reducing HIV transmission (and prevalence) is likely to be undetectable (unless accompanied by substantial changes in behavior), (ii) the transmission rate of drug-resistant HIV will be below the WHO surveillance threshold of 5%, and (ii) the majority of cases of drug-resistant HIV that will occur will be due to acquired (and not transmitted) resistance. For the next decade, large-scale surveillance for detecting transmitted resistance in Africa is unnecessary. Instead, we recommend that patients should be closely monitored for acquired resistance, and sentinel surveillance (in a few urban centers) should be used to monitor transmitted resistance.

HIV and pregnancy: is the outlook for mother and baby transformed?

PURPOSE OF REVIEW

Advances in antiretroviral regimens and specific obstetrical procedures have enabled HIV-positive women to have children, with a very low risk of transmitting the infection to the infant and with improved chances of seeing their children reach adulthood. New studies have given providers of care better information on how to assist women with HIV who want to have a child in the safest possible way.

RECENT FINDINGS

Highly active antiretroviral therapy can effectively control viral replication and reduce the risk of vertical transmission. The benefit of treatment for the mother and the infant must be balanced against any negative effects on pregnancy, the embryo and the fetus. Potential long-term consequences of prenatal exposure to potent compounds should also be considered and monitored. The evidence suggests that even in women with undetectable viral load, Caesarean section reduces vertical transmission to the same degree as documented previously for all women. Although the absolute risk reduction is very low, no study can show whether or not this is statistically significant and therefore women should be helped to make their individual choice. Mothers with HIV should not breastfeed in countries where formula milk is easily available, however highly active antiretroviral therapy administered to mothers or infants may reduce the risk of postnatal HIV transmission.

SUMMARY

Counselling and assistance to conceive, modification of the therapeutic regimens and options about delivery have changed dramatically since the beginning of the HIV epidemic. Nowadays, women with HIV, similarly to uninfected women, can discuss with their doctors which therapeutic and treatment options would best fit their expectations of care.

Prevention of mother-to-child transmission of HIV infection

PURPOSE OF REVIEW

Mother-to-child transmission of HIV infection is the primary cause of paediatric HIV infections worldwide. Although clinical trials show that antiretroviral therapy, elective caesarean section and formula feeding can significantly reduce the peripartum or postpartum risk of transmission, their application on a population basis is challenging. There is a need for alternative, easier and more effective interventions for population-based programmes.

RECENT FINDINGS

This review addresses recent advances in our understanding of mother-to-child transmission risk factors, including maternal viral load (in plasma, genital tract and breast milk) and gender, and determinants and rates of postnatal transmission. New information on prophylactic antiretroviral therapy includes results from randomized trials in Africa and Thailand, in addition to new information on implementation of prevention of mother-to-child transmission programmes in nontrial settings, in both developed and developing countries. Two important issues relating to use of antiretroviral prophylaxis are discussed: safety and toxicity, including new findings on haemopoiesis, prematurity and mitochondrial abnormalities in antiretroviral therapy-exposed infants and children, and resistance. Recent trends and controversies relating to mode of delivery in HIV-infected pregnant women are outlined. Regarding infant feeding, preliminary results on use of mono-antiretroviral therapy to prevent postnatal transmission in breastfeeding HIV-exposed infants are discussed.

SUMMARY

In resource-rich settings, virtual elimination of mother-to-child transmission is theoretically possible. Even in these settings, however, a substantial number of infected women are not being identified early enough for optimum application of prevention of mother-to-child transmission interventions. In developing country settings, focus is being directed towards scaling-up prevention programmes now that trials have established a variety of effective antiretroviral prophylactic approaches.