Hematopoietic Stem Cell Transplant: Infection Control - Episode 6
Roy Chemaly, MD: Viral infection in stem cell transplant recipients is pretty common, especially herpes viruses. One of the most common viral infections that we encounter after transplant is cytomegalovirus. Herpes simplex is also common, but with the regimen that we have now, that we’ve been using for years, we see much less incidence than we see with cytomegalovirus infection.
CMV infection is very common after transplant, especially in recipients who are CMV-seropositive, meaning that they have positive serologic status for this virus. So, they’ve been exposed to this virus in the past. These patients are at risk for reactivation, meaning that as soon as they receive the conditioning regimen and become immunosuppressed, their virus may show up in the blood in the form of viremia. It depends on the test that you use to identify this virus. It is very common. Depending on the type of transplant, it could be between 30% and 80%, if not more, especially in high-risk transplants like cord blood transplants or haploidentical transplants. So, it is one of the most common infections that we encounter after transplant.
The risk factors for CMV reactivation or even CMV end-organ disease, meaning when it progresses and causes end-organ damage, are practically the same types of risk factors that we see for different infections. Usually, the conditioning regimen can put them at risk, especially if it is a T-cell depleted regimen. It puts them at risk for a viral infection—mainly CMV. After the transplant and engraftment, graft-versus-host disease may occur. This is one of the main complications that is seen in allogeneic transplant recipients, and it is another risk factor for CMV reactivation. The treatment of graft-versus-host disease, with things like high-dose corticosteroids, can place patients at high risk for reactivation. So, these are the main risk factors for this kind of infection after transplant, including age and other comorbidities, as well.
Transcript Edited for Clarity