A virologic pilot study of valacyclovir in infectious mononucleosis.

Background: Infectious mononucleosis decreases the productivity of many college students and Epstein-Barr virus (EBV) infection may result in long-term immune damage.

Objectives: Evaluate the antiviral effect of valacyclovir during EBV-related acute infectious mononucleosis and explore potential clinical benefits.

Study Design: University students who presented during the first 7 days of illness were randomized to receive valacyclovir 3g/day for 14 days or not. The quantity of Epstein-Barr virus (EBV) DNA in oral and whole blood samples was determined by real-time (TaqMan) PCR. The primary outcome was the proportion of subjects with laboratory-confirmed primary EBV infection who had >or=2 log10 decrease in EBV copies/mL in oral washes during the treatment period. Secondary outcomes included clinical effects.

Results: Twenty subjects were studied. The proportion of valacyclovir recipients versus control subjects who had >or=2 log10 decrease in EBV copies was significantly greater for both oral wash fluid-derived cell pellet (P=0.03) and supernatant (P=0.001) samples. At the end of the treatment period, the number of reported symptoms (P=0.03) and the severity of illness (P=0.049) were reduced among valacyclovir recipients as compared with controls.

Conclusions: Valacyclovir therapy caused a reduction of EBV excretion and possibly produced a clinical benefit in infectious mononucleosis. Because our study was small and not placebo-controlled, these results must be confirmed by a larger, placebo-controlled trial.