Background: Influenza A infections have been described to cause secondary hemolytic uremic syndrome and to trigger atypical hemolytic uremic syndrome (aHUS) in individuals with an underlying genetic complement dysregulation. To date, influenza B has not been reported to trigger aHUS.
Case presentation: A 6-month-old boy presented with hemolytic uremic syndrome triggered by influenza B infection. Initially the child recovered spontaneously. When he relapsed Eculizumab treatment was initiated, resulting in complete and sustained remission. A pathogenic mutation in membrane cofactor protein (MCP) was detected.
Conclusion: Influenza B is a trigger for aHUS and might be underreported as such. Influenza vaccination may protect patients at risk.
Keywords: Atypical HUS; HUS; Hemolytic uremic syndrome; Influenza; Influenza vaccination; Quadrivalent; aHUS.