Post rabies vaccination immune dysregulation; Atypical hemolytic uremic syndrome, a case report

Background

Hemolytic uremic syndrome (HUS) is characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment. Atypical HUS (aHUS), which is non-Shiga toxin-associated, accounts for approximately 5 to 10% of pediatric HUS cases and is associated with significant morbidity and mortality—up to 25% mortality and 48% morbidity—since many children progress to end-stage renal disease. The condition is often caused by genetic mutations affecting complement regulation, with pathogenic variants in complement genes presenting 50 to 60% of cases, or by autoantibodies against complement factor H.

We report the first aHUS case, confirmed by whole exome sequencing, following two injections of purified Vero cell culture rabies vaccine (PCEC). The patient was effectively managed using a combination of plasma exchange and immunosuppressive therapy.

Case presentation

A previously healthy 10-year-old boy presented with clinical features of hemolysis, elevated renal function markers, and thrombocytopenia. He had no prior history of blood transfusions, bleeding episodes, nor relevant family medical history. The only notable antecedent event was a dog bite, followed by two doses of rabies vaccination with the purified Vero cell culture vaccine.

Treatment was initiated with Methylprednisolone at 30 mg/kg/day, followed by introduction of mycophenolate mofetil. Laboratory improvements were observed, yet clinical recovery was only achieved after 11 sessions of plasma exchange, highlighting the importance of early and aggressive intervention.

Conclusions

This case emphasizes a potential link between rabies vaccination and the development of aHUS in genetically predisposed individuals. It also underscores the critical role of prompt plasma exchange in achieving clinical remission in such cases. Further studies are needed to explore the underlying mechanisms and confirm this association.

Graphical Abstract

Graphical abstract summarizing the suggested pathogenesis of the case. Abbreviations: CFH: Complement Factor H, RBCs: Red blood Cells