CD40LG and viral hemorrhagic fever: Our patient's presentation was most consistent with a locally acquired acute DENV infection due to a positive dengue IgM virus antibody, along with his overall clinical presentation, despite no recent travel to known endemic areas. In the acute setting, the evaluation of a patient with suspected DENV infection should concurrently rule out other potentially relevant high-risk febrile illness causes, such as bacterial sepsis, murine typhus, acute HIV infection, viral hepatitis, rickettsial infections, other viral hemorrhagic fevers, or EBV infection.