Hepatitis A molecular epidemiology in the United States, 1996-1997: Sources of infection and implications of vaccination policy

Abstract

Background. The genetic relatedness of hepatitis A virus (HAV) isolates was determined to identify possible infection sources for case patients in the Sentinel Counties Study of Acute Viral Hepatitis. Methods. A 315-nucleotide segment of the VP1-P2 region of the HAV genome was amplified and sequenced from serum of case patients and analyzed together with risk-factor data. Results. Of 508 HAV-RNA-positive case patients, 449 (88.4%) were interviewed, and 255 (50.1%) reported ≥1 risk factor. Some 123 unique nucleotide sequence patterns (UNSPs) were identified - 77 (62.6%) from only 1 case patient and the rest in 2-99 persons. Among international travelers, a single person was more often infected with a single type of UNSP (17/54 [31.5%]), compared with other case patients (48/393 [12.2%]; P