An elderly man had been in several military conflicts during the early 1980s and received blood transfusions for injuries. He recently consulted his physician for what was diagnosed as cryoglobulinemia and glomerulonephritis. Additional testing revealed that he was infected by a flavivirus whose transmission was bloodborne. Which of the following viruses was involved in this infection?

HCV is a flavivirus that is transmitted by parenterally or sexually in the majority of cases; unlike the other members of the Flaviviridae known to infect humans, it is not transmitted by arthropods. Most new HCV infections are subclinical, and 70% to 90% develop into chronic hepatitis. Most HCV chronic cases remain without symptoms but 10% to 20% may develop to chronic active hepatitis and cirrhosis or hepatocellular carcinoma. Mixed cryoglobulinemia and glomerulonephritis complications are not uncommon with HCV (c). HAV (a) is a member of the Enterovirus genus; transmitted fecal-orally, it produces only acute disease. HBV (b), a member of the Hepadnaviridae, is transmitted similarly to HCV; it can produce acute or chronic infections. HDV (d) is a minus-sense RNA virus that can only cause infection in HBV-infected individuals. HEV is a member of the new family Hepeviridae; transmission and disease caused by HEV is similar to that of HAV, although the mortality is higher, especially in pregnant women.