Diagnosis and Screening
Persons with a first episode of acute hepatitis should be screened for all viral causes including HBV and HCV. Patients who become infected with both HBV and HCV at the same time will experience acute hepatitis due to both viruses. Other HBV/HCV co-infection occurs among chronic hepatitis B patients who later acquire hepatitis C and among chronic hepatitis C patients who later acquire hepatitis B.
Therefore, those patients with known chronic HBV or HCV who experience acute hepatitis symptoms, especially those with ongoing risk behavior for infection, should be screened for co-infection.
In addition, silent or occult HBV infection in patients with chronic hepatitis C may alter patients' clinical course and response to therapy. However, this requires further study before routine screening of HCV patients for HBV can be recommended.
Interaction of Hepatitis Viruses
Several studies have shown that the hepatitis B and hepatitis C viruses interact with each other and affect immune responses. Available evidence demonstrates that both viruses can inhibit each other simultaneously; either virus can play a dominant role; both viruses have the ability to induce seroconversion of the other; the chronology of infection has a role in determining the dominant virus; and HBV and HCV can alternate their dominance. However, the overall dominant effect appears to be HCV suppression of HBV.
HCV and Occult HBV infection
Occult or "Silent" HBV infection refers to patients who have chronic hepatitis C who have undetectable HBV (ie., low levels of circulating HBV DNA, and lack the HBsAg and HBeAg markers and their antibodies.) These patients have been shown to have more severe liver disease. Occult HBV may also be associated with increased liver inflammation, greater histological activity of hepatitis, and higher ALT levels.