AEGiS-15IAC: Effect of short course zidovudine plus single dose nevirapine on plasma viral load and intrapartum prevention of mother to child HIV transmission (MTCT) in Thailand.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

Effect of short course zidovudine plus single dose nevirapine on plasma viral load and intrapartum prevention of mother to child HIV transmission (MTCT) in Thailand.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. ThOrB1349)

Teeraratkul A, Chalermchokcharoenkit A, Asavapiriyanont S, Chotpitayasunondh T, Vanprapa N, Chaowanachan T, Mock P, Culnane M, Tappero J
Thailand MOPH - U.S. CDC Collaboration, Nonthaburi, Thailand

BACKGROUND: A decrease in MTCT by adding single dose intrapartum/infant nevirapine (NVP) to the short course zidovudine (ZDV) regimen was recently reported. This substudy describes maternal viral load (VL) response after taking and stopping ZDV+NVP and the risk of intrapartum HIV transmission (TR) in Thailand.

METHODS: 97 HIV-infected, antiretroviral naïve pregnant women were enrolled to receive 300mg ZDV twice daily from 34-36 weeks gestation, and 300mg ZDV every 3 hours and 200mg NVP once during labor at several hospitals in Bangkok. Infants received NVP 2mg/kg once, plus ZDV 2mg/kg for 4 weeks and supplemental formula feeding. Plasma samples were obtained at baseline before taking ZDV, at delivery, 1 week, 1 and 4 month postpartum (PP) to determine maternal VL (log₁₀ copies/ml) using Roche Amplicor Monitor v. 1.5. VL levels were compared using Wilcoxon signed rank tests. Infants with positive HIV PCR results within 72 hours after delivery were classified as intrauterine infection; those with positive results at 1 or 2 months were intrapartum infection.

RESULTS: During January 2001-December 2002, 97 women were enrolled; their median VL at baseline was 4.33, and median ZDV duration was 29 days. The median reduction in VL at delivery was -0.71 compared to baseline (p< 0.001), and -1.56 at 1 week after delivery (p< 0.001). VL at 1 and 4 month PP increased to higher than baseline levels (median log difference +0.11 and +0.07 respectively; p< 0.05). Using Kaplan-Meier estimation, the TR (6/97) was 6.3% (95% CI 2.9%-13.7%). The intrauterine to intrapartum infection ratio was 1:2.

CONCLUSIONS: ZDV+NVP suppressed maternal VL. The VL reduction was greatest at 1 week PP, but rebounded to higher than baseline levels at 1 and 4 month PP. The higher suppression effect at 1 week and subsequent rebound requires further study to determine the impact of adding NVP on intrapartum and postpartum transmission.

Keywords: AEGIS, Zidovudine, Nevirapine, Viral Load, HIV Seropositivity, Acquired Immunodeficiency Syndrome, Thailand, Single Person, Mothers, Delivery, Obstetric, Child, Humans, Female, Infant, Pregnancy, transmission, prevention & control, surgery

040711
ThOrB1349