Vidarabine therapy for severe chronic active Epstein-Barr virus infection

Purpose: Severe chronic active Epstein-Barr virus infection (SCAEBV) is an intractable disease with a poor prognosis, and a definitive treatment has not been established. We administered vidarabine to patients with natural killer (NK) cell-type SCAEBV and evaluated clinical and virologic effects. Patients and Methods: Four patients with SCAEBV were enrolled in this study. These patients had various symptoms, including fever, chronic hepatitis, hepatosplenomegaly. and hypersensitivity to mosquito bites. All patients had increased numbers of NK cells in their peripheral blood, and most of these were infected with EBV. Viral load was measured by in situ hybridization and quantitative polymerase chain reaction (PCR). Results: The patients all responded to the therapy, and their symptoms improved. After the therapy, the number of NK cells in their peripheral blood decreased. In two patients who were closely monitored, the viral load measured by in situ hybridization and quantitative PCR decreased in parallel with the symptomatic improvement. After discontinuing this drug, the patient's symptoms returned and the Epstein-Barr virus load increased again. Conclusion: These results indicate that vidarabine therapy is a therapeutic choice to control SCAEBV, although its effect may be transient.