Human bocavirus 1 viremia-associated pediatric sepsis with a triphasic urinary course: a case report

Human bocavirus 1 (HBoV1) is a common pediatric respiratory virus, yet, its potential to cause severe systemic illness as a sole pathogen and its specific effects on the urinary system are not fully recognized. This report describes the first case of pediatric sepsis, meeting the 2024 Phoenix sepsis criteria, caused by high-load HBoV1 viremia, which was characterized by a novel triphasic urinary course.

A previously healthy 4-year-old girl presented with fever and cough and developed asymptomatic sterile pyuria on illness day 4. On day 7, her condition deteriorated to sepsis (Phoenix Sepsis Score of 2), with acute respiratory distress and a depressed level of consciousness. Blood metagenomic next-generation sequencing (mNGS) identified high-load HBoV1 viremia (7,513 reads) as the sole pathogen, with negative blood and urine cultures. During the septic peak, urinary tract ultrasonography was normal; however, follow-up imaging on day 13 revealed delayed-onset, non-obstructive pyelectasis and increased post-void residual (PVR) volume. These functional abnormalities were resolved completely within 2.5 months.

HBoV1 can act as a sole pathogen to cause pediatric sepsis. The observed triphasic urinary course-early sterile pyuria, imaging quiescence at the sepsis peak, and delayed functional impairment-supports an inflammation-mediated pathogenesis rather than direct viral invasion. This case highlights the critical role of advanced molecular diagnostics in identifying viral etiologies in culture-negative sepsis and underscores the necessity of longitudinal functional surveillance, as clinically significant organ dysfunction may manifest after the acute inflammatory phase has resolved.