Serum markers of an HDV superinfection of a chronic HBV carrier

The serologic response to acute HDV superinfection in a chronic HBV carrier must be distinguished from acute HBV/HDV coinfection. HBsAg is present in both situations, but IgM anti-HBc should be negative in acute HDV superinfection. The diagnosis is made more difficult since HDV superinfection may cause transient suppression of HBV replication, transiently resulting in very low and rarely undetectable levels of HBsAg. As in patients with acute HBV/HDV coinfection, patients with acute HDV superinfection are usually positive for HDAg and/or HDV RNA in serum at the time of presentation. However, in contrast to acute coinfection, acute HDV superinfection is characterized by persistent detection of HDV RNA in serum and rapidly increasing titers of anti-HDV (total and IgM).