Neonatal Sepsis Caused by Human Parechovirus Type A3 With Marked Hyperferritinemia: A Case Report

<b>Background:</b> In neonates and young infants, human parechovirus A3 (PeV-A3) is associated with severe infections, such as sepsis and encephalomyelitis. However, the mechanisms behind severe illness and the proper indications and methods for treatment remain ambiguous. <b>Case Report:</b> A previously healthy 25-day-old female was admitted to our hospital with a history of high-grade fever, a growling voice, and poor feeding. Upon examination, she appeared lethargic and somnolent, exhibiting symptoms of tachycardia, tachypnea, and peripheral coolness. Sepsis evaluations, including the FilmArray Meningitis/Encephalitis panel, confirmed the presence of PeV-A3 infection. Empirical antibiotic therapy with ampicillin and cefotaxime was started. The fever subsided by Day 4, and a negative bacterial culture indicated that antibiotics were no longer necessary. However, on Day 5, the patient experienced a drop in platelet count, elevated liver enzymes, and hyperferritinemia (ferritin level of 37,223 ng/mL). Despite the high ferritin levels, hemophagocytic lymphohistiocytosis (HLH) was not observed, and the patient was treated without immunosuppressive therapy. Her condition improved, and she was discharged on Day 14. The isolated PeV was genotyped as PeV-A3. <b>Conclusions:</b> PeV-A3 infections often link to hyperferritinemia. Although some studies indicate that steroids and immunosuppressants might be beneficial, this case shows that diligent observation could be adequate, even with high ferritin levels. Monitoring clinical status and lab results to assess whether treatment is necessary is crucial.