Viral Reactivation in Immunocompetent Critically Ill Patients

The course of critically ill patients admitted to the intensive care unit very often may be complicated by viral infections. Latent viruses may reactivate in ‘apparently’ immunocompetent critically ill patients as consequence of inflammatory and immune dysregulation secondary to critical illness. Evidence suggests that reactivation correlates with worse clinical outcomes, including increased mortality. Highly sensitive molecular diagnostic techniques have enhanced the ability to detect viral pathogens, but still consensus definitions for reactivation and subsequently the discrimination between reactivation and overt infection in critically ill patients are lacking. Despite the progress in detecting viral pathogens, their role in clinical outcomes is obscured. Furthermore, the role of antiviral therapy, either prophylactically/preemptively or as treatment after virus detection, has to be further investigated. The question of whether reactivation is the cause or a surrogate marker of underlying severity of illness has not yet been fully elucidated.