HCV Genotype and Risk Factors Among Blood Donors in Sao Paulo, Brazil

Abstract

Background/Case Studies: In Brazil most HCV infections are caused by genotypes 1, 2 and 3. The objective of the study was to characterize the distribution and risk factors associated with HCV genotypes among blood donors in São Paulo. Study Design/Methods: Repeat reactive donors are routinely asked to return for retest and counseling, when they respond to questions related to risk factors. We have analyzed 183 donors who returned for counseling from 2007 to 2010 and were confi rmed to be HCV positive by a positive immunoblot. Samples were submitted to genotyping, by sequencing the non-structural 5b (NS5b) region of the virus. HCV viral load was determined using a home brew real time PCR that target the 5 non-coding region (5 NCR) of the HCV genome with a sensitive of 400 UI/mL. Results/Findings: Of the 183 samples, 161(88%) had RNA detectable by both PCR. There were 5(3%) samples with viral load > 400 to 10,000 UI/mL, 16(10%) with 10,000 to 100,000 UI/mL, 49(30%) with 100,000 to 1,000,000 UI/mL, and 91(57%) with > 1,000,000 UI/mL. Of the 161 samples, 71(39%) were typed as 1b, 56(31%) as 1a, and 27(15%) as 3a, and 7(4%) as others (2b, 2c and 4). Genotypes were not associated with gender, skin color and educational level but genotype 3a was more frequently found among donors older than 40 years (p = 0.012). Viral load was not associated with gender and age, but genotype 3a (log = 5.41) had a lower log mean than genotype 1a (log = 5.98, p = 0.007), and genotype 1b (log = 6.42, p = 0.02). Of the 183 HCV + donors, 20(10.9%) referred previous blood transfusion and 11(6%) intravenous drug use. There was no difference in prevalence of these risk factors among genotypes found (p = 0.257 and p = 0.276, respectively).Conclusion: Our results show a predominance of subtype 1b and a rare subtype 4 among blood donors in Brazil. Subtype 3a was associated with lower viral load and with older age. Most donors did not disclose an ordinary risk factor for HCV infection.