Thrombotic microangiopathy and acute kidney injury following vivax malaria.

BACKGROUND: Infection with Plasmodium vivax, a common human parasite, is occasionally recognized to cause severe organ dysfunction similar to P. falciparum infection. Acute kidney injury (AKI) in malaria is attributed to acute tubular necrosis; thrombotic microangiopathy is not described.
METHODS: This observational study includes patients referred to a tertiary care center in North India during June to September 2011 with severe AKI, anemia, and thrombocytopenia following vivax malaria. Renal biopsies were processed by light, immunofluorescence, and electron microscopy.
RESULTS: Nine patients (including 5 children) had persistent AKI with thrombocytopenia and variable anemia following the diagnosis of malaria. Based on peripheral smear, eight patients were diagnosed with vivax malaria and had received antimalarial therapy prior to referral; a laboratory diagnosis of P. vivax infection was made for one patient at this center. Renal histology in all cases showed features of thrombotic microangiopathy, including fibrin thrombi, subendothelial widening, and mesangiolysis, along with variable tubulointerstitial nephritis and acute tubular or cortical necrosis. Ultrastructural examination confirmed endothelial injury and subendothelial widening. All patients required hemodialysis, and six were dialysis dependent at four weeks. Delayed presentation to the hospital (P = 0.019), hemolysis on peripheral smear (P = 0.083), and prolonged oligoanuria (P = 0.036) were associated with dialysis dependence.
CONCLUSION: The association of anemia, thrombocytopenia, and renal histological evidence of thrombotic microangiopathy with vivax malaria is novel, and suggests the presence of severe endothelial injury. Further studies are necessary to confirm the association and examine the factors associated with its occurrence.