Individuals are then asymptomatic for a week. The second phase of illness occurs 17 to 18 days after infection, with the development of a mild febrile illness and a maculopapular rash. The rash initially has a discrete erythematous maculopapular appearance and then becomes reticular, disappearing in 1 to 3 weeks. Erythema infectiosum often resembles the rash of rubella. A rash does not always occur following B19 virus infection, and the only manifestation of the second phase of the illness may be a mild, influenza-like illness.
Joint involvement occurs in most women and much less frequently in men and children.
The most common presentation is of an acute-onset, symmetric arthritis involving the small joints of the hands, wrists, ankles, and knees. Recovery usually occurs within 2 to 4 weeks. B19 arthropathy may also occur in the absence of the rash. Transient lymphopenia, neutropenia, and thrombocytopenia are complications of B19 virus infection, but are rarely severe enough to cause problems. Patients develop acute symptoms of severe anemia with a critically low hemoglobin level, reticulocytopenia, and, occasionally, leukopenia and thrombocytopenia.