Molecular epidemiology of hepatitis C infection in US veteran liver transplant recipients: Evidence for decreasing relative prevalence of genotype 1B

OBJECTIVE: The U.S. Veteran population represents a unique patient group to study different HCV genotypes because of geographically diverse exposures. The aim of this study was to characterize the distribution of HCV genotype s in U.S. veterans undergoing liver transplantation (OLT), trace genotypes to modes of acquisition (risk behavior and location), and evaluate the rela tive prevalence of HCV genotypes according to the time of acquisition. METHODS: Between 10/88 and 12/95, 110 primary OLTs were performed in U.S. V eterans at our center. Forty-nine (45%) patients had detectable HCV-RNA by PCR at the time of OLT. Determination of HCV genotypes was performed by res triction fragment length polymorphism of the 5' noncoding region and classi fied according to Simmonds et al. RESULTS: Twenty-three of 49 (47%) veterans had la, 17 (35%) Ib, two (4%) 2a , three (6%) 2b, two (4%) 3a, two (4%) mixed (1a/2a, 1b/2a). This distribut ion of HCV genotypes was comparable to the genotypic distribution of a cont emporary cohort of nonveteran OLT recipients at the University of Washingto n. There was a statistically significant association between illicit inject ion drug use (IDU) and la, with 63% of la patients having IDU whereas only 14% of Ib patients admitted to IDU (p = 0.03). All patients in whom the mod e of acquisition was unknown had genotype Ib (p = 0.04). Intranasal cocaine use was strongly correlated with IDU (p = 0.002). Patients who had tattoos but no history of blood transfusion (BT) or recreational drug use had geno type 1 (2 had la, 2 had Ib; p = NS). Twenty two (45%) patients had serologi cal evidence of prior hepatitis B (HBV) infection. Patients who had genotyp e :2a, 2b, 3a, or mixed were much more likely to have had HBV (seven of nin e, 78%) than patients with genotype la or Ib (15 of 40, 37.5%) (p = 0.03). There was no significant correlation between BT, dates, or military branch of service, high risk behavior in Southeast Asia, level of education, ethni city, and particular genotype(s). Whereas the proportion of 1b accounting f or HCV infection in patients with a first exposure before 1968 was 50%, all patients with a first exposure post-1975 were non-lb (p = 0.04), suggestin g a change in the epidemiology of HCV in our cohort. CONCLUSIONS: In U.S. Veterans undergoing OLT: 1) 45% had PCR-confirmed HCV infection, 2) la was the predominant genotype and was associated with IDU, and 3) a significant decrease in the prevalence of genotype Ib from the pre -Vietnam era to post-1975 suggests a changing epidemiology of HCV genotypes . (C) 1999 by Am. Coll. of Gastroenterology.