Herpes Simplex Virus Shedding in Bone Marrow Transplant Recipients During Low-Dose Oral Acyclovir Prohylaxis

A 400mg dose twice-a-day oral acyclovir prophylaxis regimen was evaluated in 50 allogeneic transplant recipients. Twenty (40%) patients experienced 24 episodes of herpes simplex virus (HSV) shedding; l7 (70.8%) occurring during prophylaxis. Thirteen of such episodes were asymptomatic and, in three, it was difficult to differentiate severe mucositis from viral lesions. In the remaining one, HSV pneumonia was suspected after a bronchoalveolar lavage (BAL) procedure performed in an attempt to early detection of cytomegalovirus (CMV). All cases responded to acyclovir therapy or dose adjustment suggesting that acyclovir resistance did not account for the occurrence of infection in our patients. These data demonstrated that oral acyclovir prophylaxis, 400mg dose twice-a-day, was inadequate to suppress viral shedding. The bronchoalveolar lavage procedure in a patient with HSV shedding could precipitate HSV spread to the lungs and the occurrence of pneumonia.