Acute delta hepatitis without circulating HBsAg.

Infection with the delta agent can only occur in the context of coexistent hepatitis B virus infection. We describe a patient in whom the clinical features of acute delta hepatitis developed when seroconversion from hepatitis B surface antigen to antibody had already occurred and diagnosis of recent acute hepatitis B was based on high titre IgM antibody to hepatitis B core antigen. We discuss the significance of such a serological profile, not previously described.