Hepatitis delta virus infection in Northern Ireland 1970-1989.

The incidence of hepatitis delta virus (HDV) infection in Northern Ireland (1970-1989) was tested by enzyme linked immunosorbent assay in 401 hepatitis B surface antigen (HBsAg) positive sera. Hepatitis delta antigen (HDAg) was tested in 388 patients and antibody to delta antigen (anti-HD) in 401 patients. Four patients (1.03%) were HDAg positive. Nine patients (2.24%) were positive for anti-HD and after acid pre-treatment of sera from eight of these patients, five were positive for HDAg. The overall incidence of HDV markers was 3.27%, which reflects the low incidence in HBsAg carriers in Northern Ireland (who were in high risk groups for delta hepatitis). The use of acid treatment of the sera to break up antigen/antibody complexes has been a useful technological improvement in the identification of this virus.