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Parvovirus B19 infection:
humans the only known host, mostly self-limited with
life-long immunity
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Virus binds
to blood group P antigen receptors
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Clinical
expression: erythema infectiosum in children (Fifth
disease), arthralgias and arthritis in adults
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Effect on
hematopoiesis: healthy individuals - transient arrest of
erythropoiesis with mild hemoglobin drop; patients with
hemolytic disorder - transient aplastic crisis;
immunocompromised individuals - pure red cell aplasia
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Peripheral
blood: normochromic normocytic anemia with
reticulocytopenia that is resistant to erythropoietin
therapy, normal WBC and platelet counts or varying
degrees of cytopenia
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Bone marrow:
giant proerythroblasts (lantern cells) with fine
megaloblastoid chromatin, loss of normal tinctorial
quality, nuclear swelling with dissolution of the
nucleus, prominent intranuclear inclusion.. Little
maturation occurs beyond the proerythroblast.
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