Hemolytic uremic syndrome associated with Bordetella pertussis infection in a 2-month-old infant carrying a pathogenic variant in complement factor H

Background Hemolytic uremic syndrome (HUS) has been associated with a number of infectious agents. We report here the case of an infant with severe Bordetella pertussis infection who developed HUS. Case diagnosis/treatment A 2-month-old preterm male was admitted for severe Bordetella pertussis infection. Symptoms leading to a diagnosis of hemolytic uremic syndrome (HUS) rapidly appeared: hemolytic anemia, thrombocytopenia, and acute kidney injury. He was treated with 25 days of peritoneal dialysis and received complement-targeting therapy with eculizumab (five injections over 2 months), in addition to blood transfusions, antibiotics, and respiratory support. The outcome was favorable. The genetic workup found a complement factor H gene variant which has been associated with atypical HUS. This variant was located in the C3b-binding site and functional tests revealed that it perturbed the regulatory activity of factor H. Conclusion This case suggests that pertussis is a strong trigger of HUS and that complement investigations are necessary to guide treatment and understand the pathophysiology.