A 6-year-old boy with sickle cell disease presents with sudden pallor and lethargy. Hemoglobin has dropped from 8 g/dL to 4 g/dL and the reticulocyte count is 0.2 percent. His younger sibling recently had a mild febrile illness with red cheeks. What is the most likely cause of this child's deterioration?

• A Autoimmune hemolytic anemia due to Mycoplasma pneumoniae
• B Transient marrow suppression by parvovirus B19 ✓
• C Splenic sequestration crisis triggered by influenza
• D Iron deficiency superimposed on chronic hemolysis

Explanation

Parvovirus B19 selectively infects and destroys erythroid precursors via the P antigen. In children with shortened red cell survival such as sickle cell disease, this transient aplastic crisis causes abrupt severe anemia with profound reticulocytopenia. The sibling's slapped-cheek illness is the classic clue to exposure. Splenic sequestration would show a rapidly enlarging tender spleen and thrombocytopenia rather than reticulocytopenia, and autoimmune hemolysis produces a brisk reticulocyte response.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.