We read with interest the editorial by Di Bisceglie and Negro (1) and the paper by Buti et al. (21, in which the authors write about diagnosis of hepatitis delta virus (HDV) infection. In their editorial, Di Bisceglie and Negro (1) identify the discrepancy that exists in the reports with regard to the usefulness of the test for delta antigen (HDAg) in the diagnosis of acute HDV infection.
We tested for HDAg by enzyme-linked immunoassay (Deltassay Ag; Noctech Ltd, Dublin, Ireland) 101 serum samples from 38 patients with HBV and HDV coinfection. The samples were obtained at different times after the onset of symptoms of acute hepatitis: 12 during wk 1, 13 during wk 2, 20 during wk 3, 19 during wk 4 and 37 between wk 5 and wk 8. Positivity for HDAg was 83.3% in the first week, 100% in the second, 65% in the third and 42% in the fourth and 8.1% between the fifth and eighth weeks. Persistence of HDAg was < 2 wk in all patients except for two in whom HDAg remained positive-for 3 wk in one patient and for 5 wk in the other. Compared with IgM antibody to HDV virus (anti-HD) and IgG anti-HD (Sorin Biomedical; Saluggia, Italy), HDAg was the best marker for acute HDV infection during the first and the second weeks. Our findings are similar to those observed by Shattock and Morgan (3) and by Buti et al. ( 4) -probably because we used the same assay-and they support the clinical usefulness of the test for HDAg.
In chronic HDV infection serum HDAg is rarely detected, as noted by Di Bisceglie and Negro (1). However, we detected HDAg by enzyme-linked immunoassay in 10