Occurrence of atypical HUS associated with influenza B

Hemolytic uremic syndrome (HUS) is a disease characterized by thrombotic microangiopathy with a triad of non-immune hemolytic anemia, thrombocytopenia, and renal impairment. Approximately 10% of cases of HUS are classified as atypical (aHUS). While today many genetically forms of aHUS pathology are known, only about 50% of carriers precipitate the disease. The reason remains unclear, and triggering events like intercurrent infections have been postulated. In rare cases, influenza A is the known trigger of aHUS; however, no cases of influenza B have been reported. Conclusion: We describe for the first time that influenza B strain as a trigger for aHUS in children with primary hereditary forms. We also showed in our three cases that immunization appears to be safe; however, this needs to be confirmed in a larger cohort.What is Known:• Known triggers of aHUS are infectious specimen.• Influenza A-associated aHUS cases are rarely published.What is New:• aHUS can be triggered by influenza B virus infection.• Influenza vaccination of patients with aHUS appears safe.