Hepatitis A IgM antibody (IgM anti-HAV), detected by commercially available solid-phase radioimmunoassay, is an accepted marker of acute viral hepatitis A infection. However, persistence of this serological marker far beyond the acute illness and immediate convalescent period has been reported. To determine the persistence of IgM anti-HAV following clinically manifest acute hepatitis A infection, 59 patients with this diagnosis were followed prospectively until this marker disappeared or persisted for greater than 60 days. Timed from the onset of jaundice, IgM anti-HAV persisted for less than 30 to greater than 420 days; most patients became seronegative by 120 days. These findings suggest that some patients may become seronegative early in the disease course while others (13.5%) remain positive for prolonged periods greater than 200 days. Awareness of this marked variability is important in the interpretation of IgM anti-HAV as a serologic marker of recent hepatitis A infection.
Acute viral hepatitis A is a common diagnostic problem requiring accurate etiological identification, when possible, to assess prognosis and appropriate use of immune serum globulin. Unlike the hepatitis B virus, there is no direct test in serum for the hepatitis A virus. However, with development of methods to detect hepatitis A specific antibodies, diagnosis of acute viral hepatitis A is now made by serological detection of hepatitis A virusspecific IgM antibody (IgM anti-HAV). This is done by a solid-phase radioimmunoassay which is sensitive and specific (1-5). IgM anti-HAV becomes detectable at the onset of clinical illness and is always present by the onset of jaundice (1, 5). Its duration is usually less than 120 days, but longer persistence occurs (1, 3-5). However, the frequency of a prolonged positive test (>200 days after onset of jaundice or symptoms) has not been adequately documented. The purpose of the present study was to examine prospectively persistence of IgM anti-HAV following clinically manifest acute viral hepatitis A and thus evaluate its diagnostic usefulness as a marker of acute disease.