Respiratory viral infections in transplant recipients

Purpose of review: The leading cause of death in solid organ and hematopoietic stem cell transplant recipients is infection. The respiratory viruses are increasingly recognized as significant pathogens in these populations. Recent findings: Respiratory syncytial virus is the most common respiratory viral pathogen in transplant recipients, but little progress has been made in managing respiratory syncytial virus infections. Influenza annually causes increased morbidity and mortality in transplant recipients. M2 (amantadine and rimantadine) and neuraminidase inhibitors, alone or in combination, result in a shorter duration of viral replication, decreased progression to lower tract disease, and reduced mortality. Parainfluenza continues to be recognized as a significant pathogen that seems to be a strong risk factor for the development of acute and chronic rejection. Therapeutic options remain limited for parainfluenza infections. Adenovirus has recently been shown to frequently cause viremia, which is often asymptomatic and resolves without therapy. Cidofovir seems to be the drug of choice in managing disseminated or life-threatening adenoviral infections. Rhinoviruses have recently been recognized to cause significant lower tract disease and increased mortality. Last, human metapneumovirus and coronaviruses, including severe acute respiratory syndrome - associated coronavirus, have been recently discovered and are increasingly recognized as significant pathogens in transplant recipients. Therapeutic options for both viruses are not yet clearly defined. Summary: Studies published over the past several years have documented new respiratory pathogens, have resulted in improved understanding of their impacts, and have led to improvements in management, particularly of influenza and adenovirus infections in hematopoietic stem cell transplant and solid organ transplant recipients.