The CDC- Persons receiving cytotoxic or immunosuppressive therapy. Persons receiving cytotoxic or immunosuppressive therapy (e.g., chemotherapy for malignant diseases, immunosuppression related to organ transplantation, and immunosuppression for rheumatologic and gastroenterologic disorders) should be tested for serologic markers of HBV infection (i.e., HBsAg, anti-HBc, and anti-HBs). Prophylactic antiviral therapy can prevent reactivation in HBsAg-positive patients (13,101).