Case report: Be alert to parvovirus infection in patients with unexplained anemia after cerebral hemorrhage surgery.

Background: Human parvovirus B19 (PVB19) is a highly prevalent single-stranded DNA virus that infects a large proportion of the global population. It can involve multiple organ systems, leading to a broad spectrum of clinical manifestations. While most infections in immunocompetent individuals are mild and self-limiting, PVB19 can occasionally cause severe and diverse complications. Case presentation: We report a rare case of an immunocompetent patient who experienced unexplained clinical deterioration following surgical evacuation of an intracerebral hemorrhage. The patient presented with refractory anemia, impaired consciousness, fever, seizures, and progressive dysfunction of the cardiac, hepatic, and renal systems. Metagenomic next-generation sequencing revealed high levels of PVB19 DNA in the cerebrospinal fluid, blood, and pleural effusion. The patient was treated with intravenous immunoglobulin (IVIG) therapy and supportive care. Following treatment, improvements were observed in consciousness, mobility, and anemia. However, renal function failed to recover and ultimately progressed to renal failure, necessitating renal replacement therapy. Conclusion: This case underscores the potential severity of PVB19 infection following cerebral hemorrhage surgery, particularly when accompanied by unexplained anemia. Accurate diagnosis requires a high index of suspicion and the use of advanced diagnostic tools. Management primarily involves IVIG therapy and supportive care. This case highlights the importance of expanding the differential diagnosis in postoperative patients presenting with unexplained anemia and multi-organ dysfunction, as early recognition of atypical infections may improve clinical outcomes.