RELIABILITY OF A HISTORY OF PREVIOUS VARICELLA INFECTION IN ADULTS

Context.-Apparent second episodes of varicella are reported in immunoc ompetent hosts, but laboratory confirmation of prior immune status has rarely been possible. Objective.-To evaluate adult patients with vari cella who claimed to have had previous varicella to determine whether they had true second episodes or primary cases with inaccurate clinica l histories. Design.-Adult subjects with varicella who enrolled in an antiviral treatment trial were interviewed about a history of varicell a. The clinical course of varicella was documented prospectively in al l subjects. Serum samples that predated the acute illness were obtaine d from the US Navy's central serum storage facility for subjects who r eported a previous episode of varicella. These stored samples were tes ted in parallel by enzyme-linked immunosorbent assay, latex agglutinat ion, and Western blot for IgG antibodies to varicella-zoster virus (VZ V), Participants.-Twenty military personnel with varicella and a histo ry of the disease. Setting.-A military hospital in San Diego, Calif. M ain Outcome Measure.-Presence or absence of antibodies to VZV. Results .-Twenty (10.8%) of 184 adults with serologically confirmed acute vari cella reported a prior history of varicella. The clinical course of th ese 20 patients did not differ from those with no history of varicella . Serum samples that had been collected a mean of 12.4 months (median, 12 months; range, 3 days to 34 months) before the incident episode we re available for 19 subjects. All 19 serum samples lacked IgG antibodi es to VZV, Conclusion.-A history of previous varicella infection in ad ults with varicella may not be reliable. True second episodes of varic ella are probably rare in immunocompetent adults.