Managing HBV in patients with impaired immunity.

Chronic hepatitis B is one of the most common infectious diseases worldwide. In patients with an impaired immune system the prevalence of HBsAg is even higher and the course of hepatitis B infection is often aggravated. In HIV/HBV co-infected patients, liver related morbidity and mortality can be reduced by implementing highly active antiretroviral treatment (HAART) that contains substances active against HBV. Reactivation of HBV during chemotherapy may occur in HBsAg positive patients but can even occur in serologically recovered anti-HBc positive, HBsAg negative patients resulting in high mortality from liver disease. HBsAg positive patients irrespective of HBV DNA levels should receive preemptive treatment with HBV polymerase inhibitors which should be continued for 12 months after cessation of chemo- and or immunosuppressive therapy. The combination prophylaxis of passive immunisations with hepatitis B immunoglobulins (HBIG) and nucleos(t)ide analogues (NUC) is able to reduce HBV recurrence rates after transplantation to 0-10%. This review will summarise the current knowledge on pathogenesis, frequency and treatment options of HBV reactivations in patients with impaired immunity.