Chronic Fatigue Syndrome after Human Parvovirus B19 Infection without Persistent Viremia

<i>Background:</i> It is unclear how often chronic fatigue syndrome (CFS) appears after human parvovirus B19 (B19) infection and whether prolonged B19 viremia or some other factors cause CFS. <i>Objectives:</i> To determine how often CFS appears after B19 infection and whether prolonged B19 DNA presence, antibody production and persistently reduced complement levels occur in CFS patients after B19 infection. <i>Methods:</i> Clinical findings were examined in 210 patients after B19 infection, and CH50, C3 and C4 levels were determined. B19 DNA and antibodies to B19 were also tested in 38 patients’ sera including 3 with CFS. <i>Results:</i> Serum B19 DNA disappeared after 4–5 months in all 18 patients tested. There are no differences in B19 DNA-positive period between patients with and without persistent symptoms. IgM antibody titers to B19 became reduced after 2 months in all 38 patients. Complement levels persistently decreased in a greater proportion of patients with persistent symptoms. <i>Conclusions:</i> The present study suggests that we should consider the possibility of CFS after B19 infection and that CFS may be derived from several aspects other than prolonged B19 DNA presence in sera.