Haematological consequences of parvovirus B19 infection.

Parvovirus B19, a member of the Erythrovirus genus, is the only member of the Parvoviridae family known to be pathogenic in humans. Erythroviruses are so named because of their tropism and selective replication in erythroid progenitor cells. Haematological consequences of B19 infection arise due to a direct cytotoxic effect on erythroid progenitors in bone marrow with interruption of erythrocyte production. In addition, the physiology of host haematopoiesis and competence of the immune response each determines clinical manifestations of B19 infection: in individuals with underlying haemolytic disorders, B19 infection causes transient aplastic crisis; in immunocompromised patients, persistent B19 infection may develop that manifests as pure red cell aplasia and chronic anaemia; B19 infection in utero may result in fetal death, hydrops fetalis, or congenital anaemia. Diagnosis is based on examination of bone marrow and B19 virological studies. Treatment of persistent infection with immunoglobulin leads to a prompt resolution of the anaemia.