Latent viral infections in critically ill patients

The herpesvirus family all cause latent infections in humans, and similar rates of infection, morbidity and mortality have also been reported in comparable patients with herpes simplex virus [2,3]. Nevertheless, although infection rates with latent herpesviruses appear high, the majority of seropositive patients do not suffer reactivation. Acquisition of herpesviruses in infancy results in trivial clinical illness, suggesting we have co-evolved effectively with these pathogens. Indeed a recent report highlighted how herpesviruses offer protection from bacterial infections [4]. Latent, but not acute, infection conferred a 100-fold to 1,000-fold reduction in bacterial burden due to IFNγ-dependent macrophage activation. Latency with all herpesviruses in humans is probably associated with frequent subclinical reactivation, which may lead to reticuloendothelial cell priming [5].