Subclinical infection of the respiratory tract of immunocompromised

We read with interest a recent article by Wilbom et al.’who presented an extensive study on the prevalence and type of human herpesvirus-6 (HHV-6) infection in 57 individuals receiving bone marrow transplants (BMTs). The presence of HHV-6 DNA was followed before and after BMT by polymerase chain reaction (FTR) in their peripheral blood mononuclear cells, oral lavage fluids, and urine. However, because of the low incidence of serious complications in their study group (only two of the patients developed interstitial pneumonitis), the investigators could not conclude that HHV-6 had implications in the clinical outcome. Indeed, the association of HHV-6 with diseases other than exanthem subitum, and in particular its potential role as the causal agent of interstitial pneumonitis in the immunocompromised host has been largely debated during the last year, and several articles and correspondence have not been yet conclusive on this matter. 2-9