ORAL ACYCLOVIR PROPHYLAXIS OF VARICELLA AFTER INTIMATE CONTACT

Objectives. Whether oral acyclovir (ACV) given in late incubation can prevent clinical varicella or not. Materials and methods, Twenty-seven healthy infants and children susceptible to varicella received oral A CV (40 mg/kg daily in four divided doses) for 5 days, starting 9 or 11 days after exposure from the index case in the family (2 in the class room), The clinical features were compared with 13 control children wh o did not receive ACV, Enzyme-linked immunoassay was used to detect va ricella-zoster virus (VZV) antibody and, in follow-up immunologic stud ies, lymphocyte proliferative response was added. In some cases, blood culture and polymerase chain reaction with Southern hybridization wer e used for detection of viremia, Results. Among the 27 children in the treatment group, two (7.4%) developed the disease and seroconversion was observed in 17 subjects (63%). Follow-up immunologic studies in 12 of these 17 seroconverted subjects 30 months later showed persistent cellular and/or humoral immunity to VZV, Only one subject, bled 11 day s after exposure, had positive VZV DNA and blood culture for VZV, On t he other hand 10 of 13 (77%) control subjects developed clinical varic ella. Conclusions. Oral ACV administration to healthy susceptible subj ects at the beginning of secondary viremia in the late incubation peri od (9 days after exposure) can effectively prevent or modify clinical varicella.