Acyclovir treatment in primary Epstein-Barr virus infection. A double-blind placebo-controlled study.

Acyclovir (ACV), which effectively inhibits in vitro Epstein-Barr virus (EBV) production, was tested in 31 patients with clinical and laboratory diagnosis of infectious mononucleosis (IM) in a double-blind trial. Patients with symptoms not exceeding 7 days were randomised to intravenous ACV 10 mg/kg or placebo (PLO) treatment every 8 h for 7 days. Clinical, virological and immunological parameters were followed in each patient before, during and after treatment. There were no significant differences (p greater than 0.05) between the treatment groups for any single clinical symptom between the treatment groups. If data concerning duration of fever, weight loss, tonsillar swelling, sore throat and patient self-assessment of general health were combined, a significant effect (p less than or equal to 0.01) favouring ACV treatment was determined. ACV significantly inhibited oropharyngeal EBV shedding (p less than or equal to 0.001), but the salivary EBV titer returned within 3 weeks after cessation of treatment. Specific cellular and humoral immunity was not affected, nor was the development of virus latency.