Severe Plasmodium vivax Malaria Complicated by Secondary Hemophagocytic Lymphohistiocytosis, Disseminated Intravascular Coagulation, and Acute Pancreatitis: A Case Report.

Plasmodium vivax (P. vivax) malaria, once regarded as a comparatively benign infection, is increasingly recognized as a cause of severe, potentially life-threatening multisystem disease. Concurrent secondary hemophagocytic lymphohistiocytosis (HLH), disseminated intravascular coagulation (DIC), and acute pancreatitis complicating P. vivax infection is exceptionally rare. A previously healthy 19-year-old Bangladeshi woman presented with a 5-day history of high-grade fever with rigors, generalized weakness, and upper abdominal pain. Laboratory evaluation demonstrated pancytopenia, markedly elevated ferritin (28,839 ng/mL), hypertriglyceridemia, hypofibrinogenemia, elevated transaminases, coagulopathy, and elevated pancreatic enzymes. Malaria rapid diagnostic testing (RDT) was positive for P. vivax; peripheral blood smear was negative and PCR was unavailable. The patient fulfilled six HLH-2004 diagnostic criteria, met International Society on Thrombosis and Hemostasis (ISTH) criteria for overt DIC, and satisfied revised Atlanta criteria for acute pancreatitis. Intravenous artesunate with multidisciplinary supportive care resulted in progressive clinical and biochemical improvement. HLH-directed immunosuppressive therapy was not required. She was transitioned to oral artemether-lumefantrine and primaquine for radical cure and remained asymptomatic at follow-up. This case illustrates the evolving recognition of P. vivax as a pathogen capable of triggering complex hyperinflammatory and multisystem complications. Early identification of underlying infection and prompt antimalarial therapy may be sufficient to achieve remission in infection-associated HLH without immunosuppression. Clinicians in endemic regions should maintain heightened vigilance for these rare but life-threatening complications.