An 11-year-old girl presented with asthenia, weight loss and fever of 13 days' duration, with fever peaks every day, with no fixed time pattern. Examination revealed an asthenic habitus (weight P3-10) and thick, whitish mucus in the cavum, with the rest of the examination being normal.
Laboratory tests on admission: leukocytes 4060/µl (segmented 59%, white blood cells 6%, lymphocytes 33%, monocytes 2%), Hb 13.3 g/dl, Ht 38%, platelets 25 000/µl. Smear showed red blood cells, activated lymphocytes and neutrophil vacuolisation; CRP 58.1 mg/l (88.2 mg/l, at an ED visit two days earlier); proteinuria in the urine sediment. He was admitted with intravenous amoxicillin-clavulanic acid treatment due to smear findings and elevated acute phase reactants. She remained afebrile from the second day of admission. During her admission she presented micropetechiae in the lower limbs and dorsum of the feet on the second day, as well as oral mucosal bleeding on the third day; in view of these findings and the fact that on the fourth day she presented a blood test of 8000 platelets/µl, it was decided to administer a dose of gamma globulin, with an adequate response to treatment, presenting clinical improvement and an increase in platelet count to 16,000/µl.

The patient was diagnosed with a long-standing fever with no fever, positive IgM parvovirus B19, and a diagnosis of parvovirus B19 infection, secondary plateletopenia and mild proteinuria, with the rest of the renal function remaining normal.