Introduction:  Co-infection with hepatitis C virus (HCV) and human immunodeficiency virus type I (HIV-1) is a significant international public health problem. Given the potential for chronic HCV-associated morbidity, we evaluated the prevalence of HCV infection among HIV-infected pregnant women enrolled in the Breastfeeding, Antiretroviral, and Nutrition (BAN) Study in Lilongwe, Malawi (www.thebanstudy.org).

Methods:  Serum collected from 2043 HIV-infected pregnant women was screened for HCV using a chemiluminescent immunoassay (CIA) for anti-HCV IgG (Vitros ECi, Ortho CD, Rochester, NY). All specimens with a signal-to-cut-off (S/CO) ratio of 1.0 and above were considered anti-HCV CIA reactive. All anti-HCV reactive specimens were subject to confirmatory testing with a recombinant immunoblot assay (RIBA HCV 3.0, Novartis V&D, Emeryville, CA) and HCV RNA test. Proportions and confidence intervals, using binomial exact approximations, were calculated.

Results:  Of 2043 women tested, 113 (5.5%) were anti-HCV reactive; 14/113 (12.4%, 95%CI, 6.9 to 19.9%) had a CIA S/CO ratio above 8.0. Of the 113 anti-HCV reactive, 108 were tested with RIBA. Only 2 of the 108 (1.9%, 95%CI 0.2 to 6.5%) were positive, consistent with confirmed past or current HCV infection; 26 (24.1%, 95%CI 16.3 to 33.3%) were indeterminate, and 80 (74%, 95%CI 64.8 to 82.0%) were negative. All 113 specimens tested were HCV RNA negative. The mean (SD) age of study participants was 25.8 (5.1) years, and women had a median CD4 count (IQR) of 420 (300 to 573) cells/mm³, alanine aminotransferase (ALT) of 13 (10 to 15) mg/dL, and albumin of 2.8 (2.5 to 3.0) mg/dL.

Conclusions:  Although this population of HIV-infected pregnant women in Malawi demonstrates a high frequency of anti-HCV reactivity when screened (5.5%), the prevalence of confirmed past or current HCV infection is very low (<0.1%). The high HCV reactivity is most likely a false positive result in this low prevalence population.