Parvovirus B19 Infection Presenting as Acute Tubulointerstitial Nephritis in an Immunocompetent Patient: A Case Report.

A 21-year-old female patient with a history of Helicobacter pylori-associated gastritis and irregular menstrual cycles was admitted for fever, abdominal pain, vomiting, and stage 3 acute kidney injury (AKI). Three months earlier, she had presented with a pruritic rash and abdominal pain treated with amoxicillin-clavulanate, followed by recurrence of symptoms and deterioration. On admission, laboratory tests showed anemia, leukocytosis, thrombocytosis, elevated inflammatory markers, and mild proteinuria. An extensive infectious and autoimmune work-up was negative, except for positive IgM and IgG antibodies to parvovirus B19 (PVB19) and detectable viral DNA. Renal biopsy revealed acute tubulointerstitial nephritis without glomerular or vascular involvement. She was managed with supportive therapy, including hydration, antibiotics, and transfusion. Her renal function and clinical status progressively improved, with normalization of creatinine and inflammatory markers within three months. Although rare, PVB19 infection can present as acute interstitial nephritis even in immunocompetent adults. Recognition of this atypical presentation is crucial to avoid unnecessary immunosuppression and to anticipate spontaneous recovery.