Background:  The Kisumu Breastfeeding Study (KiBS) is a clinical trial to evaluate safety, adherence, and efficacy of zidovudine, lamivudine, and nevirapine from 34 weeks’ gestation through 6 months post-partum to reduce mother-to-child transmission (MTCT) among HIV-infected breastfeeding women in a resource-limited setting. ART agents were not widely available in Kenya when the study started. We sought to assess immunologic and virologic response and adherence during the intervention.

Methods:   We evaluated trends in CD4 count and viral load and adherence rates among 203 participants at baseline (34 weeks’ gestation), delivery, and 6 months’ post-partum.  Adherence rates were based on pill count, CD4 was determined on FACSCalibur, plasma viral load was measured using Roche Amplicor version 1.5.

Result:  Median age of participants was 24 years (range 16 to 39 years). The table shows CD4, viral load, and adherence of the 203 participants during the intervention period. There was a significant increase in the maternal median CD4 and a significant decrease in median viral load over the intervention. Among 163 subjects reporting ≥95% adherence at 6 months’ post-partum, 119 (73%) had undetectable viral load, while 19 (12%) had viral load ≥10,000 copies/mL. Of interest, 19 (9%) of all participants had viral load ≥10,000 at delivery, however, this proportion increased to 34 (17%) at 6 months; most of the 34 reported ≥95% adherence.

Conclusions:  In this ART-naïve population of pregnant women receiving HAART, unlikely to have resistant virus, we observed that most participants showed improvement in immunological and virological response during the intervention. However, 17% of participants showed no decline in viral load over this period, or showed initial decline and then an increase, raising the question of adherence and resistance. Further analysis of drug levels among these participants will provide better assessment of our measures of adherence. Resistance will also be evaluated. Understanding factors that could affect adherence to ART, such as stigma and fear of disclosure associated with taking ART, requires additional evaluation.

 * p <0.001