| • | polyarthritis and pruritis |
| • | should be considered when an adult woman has acute polyarthropathy (can be disabling) associated with pruritis (especially if she has been exposed to children with erythema infectiosum) |
| • | small outbreaks of fifth disease usually occur in spring |
| • | spread is by droplets of the nasopharynx |
| • | the major target of parvovirus is the bone marrow erythroid progenitor cell |
| • | the virus is cytotoxic for these cells which causes a halt in red cell production |
| • | the exanthem and polyarthralgia are the result of antibody/antigen immune complexes and occur as bone marrow recovery is under way |
| • | diagnosis: IgM antibodies |
side note:
| • | in a person with normal hematopoieses, B19 infection produces a self-limited red-cell aplasia that is clinically inapparent |
| • | in patients who have increased rates of red cell destruction or loss and who depend on compensatory increases in red cell production to maintain red cell count, B19 infection may lead to a transient, aplastic crisis |
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