HIV-1 mother-to-child transmission and drug resistance among Brazilian pregnant women with high access to diagnosis and prophylactic measures

Abstract

Background: A high-coverage public health prenatal program (70,000 women/year) from central western Brazil/Goias State has represented a unique opportunity for the early diagnosis of HIV-1 and implemen tation of strategies to prevent mother-to-child transmission (MTCT). Objectives: To investigate MTCT among a prospective cohort of HIV-1 infected mothers/exposed infants. Study design: 142 mothers/their 149 infants (2008–2010) were investigated regarding maternal viral load, CD4+cell counts, HIV-1 pol sequences; infants’ HIV-1 RNA tests (30/120days), sequential anti-HIV-1/2 serology. HIV-1 subtypes were assigned by REGA. Transmitted drug resistance was identified by the Cali brated Population Resistance tool, secondary resistance by Stanford HIV-1 Drug Resistance/International AIDS Society databases. Results: Mothers (median age = 24 years; 25/142 adolescents) were diagnosed during prenatal care (2008–2010) or previously (1994–2007). Recent cases were younger, mostly asymptomatic. Undetectable viremia and MTCT prophylaxis predominated in formerly diagnosed mothers. Recent cases had higher subtype C prevalence. One naive patient had transmitted resistance; ten antiretroviral-experienced patients had secondary resistance: 6 from MTCT prophylaxis, 4 under HAART. Late disclosure of diag nosis, vaginal delivery, breastfeeding, lack of oral zidovudine were observed in the three MTCT cases (3/149; 2.01%). Two of three infected infants harbored subtype C; infected infants/mothers did not have drug resistance mutations. Two of the transmitting-mothers had viremia <1000 copies/ml. Among exposed-uninfected infants the median time to seroreversion was 12 months. Conclusions: In this study delayed disclosure of diagnosis, partial/no preventive measures, drug resistance among asymptomatic women under prophylaxis and MTCT in low viremic mothers raise concerns. The expansion of subtype C infection corroborates surveillance of HIV-1 diversity in this region.