Cytomegalovirus infection in transplant recipients.

Cytomegalovirus infection is a frequent complication after transplantation. This infection occurs due to transmission from the transplanted organ, due to reactivation of latent infection, or after a primary infection in seronegative patients and can be defined as follows: latent infection, active infection, viral syndrome or invasive disease. This condition occurs mainly between 30 and 90 days after transplantation. In hematopoietic stem cell transplantation in particular, infection usually occurs within the first 30 days after transplantation and in the presence of graft-versus-host disease. The major risk factors are when the recipient is cytomegalovirus seronegative and the donor is seropositive as well as when lymphocyte-depleting antibodies are used. There are two methods for the diagnosis of cytomegalovirus infection: the pp65 antigenemia assay and polymerase chain reaction. Serology has no value for the diagnosis of active disease, whereas histology of the affected tissue and bronchoalveolar lavage analysis are useful in the diagnosis of invasive disease. Cytomegalovirus disease can be prevented by prophylaxis (the administration of antiviral drugs to all or to a subgroup of patients who are at higher risk of viral replication) or by preemptive therapy (the early diagnosis of viral replication before development of the disease and prescription of antiviral treatment to prevent the appearance of clinical disease). The drug used is intravenous or oral ganciclovir; oral valganciclovir; or, less frequently, valacyclovir. Prophylaxis should continue for 90 to 180 days. Treatment is always indicated in cytomegalovirus disease, and the gold-standard drug is intravenous ganciclovir. Treatment should be given for 2 to 3 weeks and should be continued for an additional 7 days after the first negative result for viremia.