Initial Seronegative West Nile Virus Encephalitis in an Immunocompromised Child.

We present a case of initial seronegative West Nile virus encephalitis in an immunocompromised child due to B-cell acute lymphoblastic leukemia. Although diagnostic guidelines for West Nile virus infection exist, we highlight that these may not be met in immunocompromised patients who may have a delayed immune response.