The etiology of acute hepatitis superimposed upon previously unrecognized asymptomatic HBsAg carriers.

To study the etiology of acute hepatitis superimposed upon previously unrecognized asymptomatic HBsAg carriers, paired sera were collected in acute and convalescence phases for measurement of HBeAg, anti-HBe, hepatitis B virus DNA and anti-delta from 76 adult patients with acute hepatitis who were HBsAg positive but IgM anti-HBc negative or positive only at low titer. None of them were IgM anti-hepatitis A virus positive on admission. Of the 34 patients who were HBeAg positive initially, two (5.9%) were diagnosed as having delta superinfection, and another two (5.9%) were suspected to have non-A, non-B virus superinfection because of a transient decrease of serum hepatitis B virus DNA. The remaining 30 (88.2%) cases were hepatitis B virus DNA negative with or without anti-HBe seroconversion on follow-up. The episodes of acute hepatitis in these cases may represent "immune clearance of HBeAg" or "immune clearance of hepatitis B virus with delayed anti-HBe seroconversion," respectively, in the natural course of chronic hepatitis B virus infection. Of the patients who were anti-HBe positive initially, 23 (54.8%) were diagnosed as having delta superinfection, including eight with de novo seroconversion of anti-delta and 15 with a rising titer of anti-delta; 10 (23.8%) were positive for hepatitis B virus DNA and were considered as reactivation of hepatitis B virus, and the other nine (21.4%) were suspected as having non-A, non-B virus superinfection.(ABSTRACT TRUNCATED AT 250 WORDS)