Influenza-associated hemolytic uremic syndrome: The pathogenic role of the virus

Typical Hemolytic Uremic Syndrome Secondary to Influenza A in a Pediatric Patient With Complex Comorbidities: A Rare Encounter

Hemolytic uremic syndrome (HUS) is a severe condition characterized by hemolytic anemia, thrombocytopenia, and acute kidney injury (AKI). It can be atypical, due to complement dysregulation, or typical, primarily linked to bacterial infections, with viral-induced HUS being extremely rare. We report the case of a six-year-old male who presented with eight days of upper respiratory tract infection symptoms. Initial treatment for tonsillitis was ineffective. He was admitted to the Pediatric Intensive Care Unit (PICU) with severe dehydration, high-grade fever, and AKI, and was initially suspected of having multi-system inflammatory syndrome in children (MIS-C). Further investigation confirmed typical HUS, likely secondary to Influenza A. The child required peritoneal dialysis and other supportive treatments until recovery. This case underscores the need to consider viral-induced HUS in pediatric patients with severe infections and complex medical presentations. An interdisciplinary approach and timely interventions were crucial for his recovery. This rare presentation of HUS associated with Influenza A highlights the importance of clinical awareness and the need for further research to improve care strategies for similar cases.

The Role of the Complement System in the Pathogenesis of Infectious Forms of Hemolytic Uremic Syndrome

Hemolytic uremic syndrome (HUS) is an acute disease and the most common cause of childhood acute renal failure. HUS is characterized by a triad of symptoms: microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. In most of the cases, HUS occurs as a result of infection caused by Shiga toxin-producing microbes: hemorrhagic Escherichia coli and Shigella dysenteriae type 1. They account for up to 90% of all cases of HUS. The remaining 10% of cases grouped under the general term atypical HUS represent a heterogeneous group of diseases with similar clinical signs. Emerging evidence suggests that in addition to E. coli and S. dysenteriae type 1, a variety of bacterial and viral infections can cause the development of HUS. In particular, infectious diseases act as the main cause of aHUS recurrence. The pathogenesis of most cases of atypical HUS is based on congenital or acquired defects of complement system. This review presents summarized data from recent studies, suggesting that complement dysregulation is a key pathogenetic factor in various types of infection-induced HUS. Separate links in the complement system are considered, the damage of which during bacterial and viral infections can lead to complement hyperactivation following by microvascular endothelial injury and development of acute renal failure.

Virus-Associated Nephropathies: A Narrative Review

While most viral infections cause mild symptoms and a spontaneous favorable resolution, some can lead to severe or protracted manifestations, specifically in immunocompromised hosts. Kidney injuries related to viral infections may have multiple causes related to the infection severity, drug toxicity or direct or indirect viral-associated nephropathy. We review here the described virus-associated nephropathies in order to guide diagnosis strategies and treatments in cases of acute kidney injury (AKI) occurring concomitantly with a viral infection. The occurrence of virus-associated nephropathy depends on multiple factors: the local epidemiology of the virus, its ability to infect renal cells and the patient's underlying immune response, which varies with the state of immunosuppression. Clear comprehension of pathophysiological mechanisms associated with a summary of described direct and indirect injuries should help physicians to diagnose and treat viral associated nephropathies.