[Primary and secondary prevention of cytomegalovirus infections in immunocompromised patients]

Seroprevalence for CMV varies from 70% in the general population to more than 90% in HIV infected patients. Immunodepression whatever its origin, either post therapeutic as in transplant recipients, or induced by HIV, leads to the reactivation of this virus, present in a latent form in the host. In CMV-seronegative patients, the main prevention is based on donor matching before a graft (graft of seronegative donor) and on the use of seronegative blood products or deleukocyted blood. Since the availability of efficient strategies of prophylaxis (before infection) or of early treatment (pre-emptive therapy), CMV disease is now infrequent in most transplantation centers. A real prophylaxis with ganciclovir is usually selected in high risk patients (lung, bone marrow transplants in case of a CMV seropositive recipient or seronegative but with a seropositive donor). It has replaced in most centers aciclovir that has only a modest efficacy. A pre-emptive therapy by ganciclovir is proposed in case of lower risk of CMV disease (kidney, liver or heart transplants) or if the local virology laboratory provides sensitive virological markers to detect the first signs of CMV reactivation. Besides viremia or pp65 antigenemia, currently used to initiate a pre-emptive therapy, the standardisation of other virological markers such as leukocytic or plasmatic PCR is in progress. The prophylaxis of CMV disease in less developed for HIV infected patients. Immunosuppression, continuously progressing in absence of antiretroviral agents, requires a continuous prophylaxis for months or years, treatment that is difficult to propose at the present time considering the modest activity of oral ganciclovir, the only oral agent available. Future progresses in this field will be obtained when a sensitive and reproductible CMV marker will allow to identify the patients at highest risk of CMV disease, and with new anti-CMV agents having a good oral bioavailability.