Misdiagnosis, treatment delays and premature closure of diagnostic workup are common consequences of reliability on specific immunoglobulin tests alone. Even though, cross-reactivity could occur with any pathogen, the possibility of reactivation of latent virus by up-regulation of innate immunity, should be taken into a consideration when clinical syndrome points in that direction. We present a case of suspected cytomegalovirus (CMV) reactivation by innate immune response to West Nile virus (WNV) infection in a patient with acute ascending paralyses and multi-organ failure.

62-year-old Egyptian woman with hypertension and chronic anemia presented with generalized weakness, nausea and vomiting, occurring shortly after a diarrheal illness. Rapidly, she developed ascending paresis, dyspnea, dysphagia, dysarthria, hypo-reflexia and was intubated. MRI Brain and spine were unremarkable. Serum serologies were positive for CMV and Toxoplasma IgM/IgG. HIV and HSV I/II tests were negative. CSF analysis showed lymphocytic pleocytosis, elevated protein and low glucose. She received  empiric coverage with broad spectrum of antimicrobials/antivirals. As multi-system complications occurred (respiratory failure, pneumonia, pancytopenia, transaminitis, acute kidney injury, heart failure and shock), she was transferred to our hospital for further evaluation where additional studies revealed negative CMV PCR, positive serum and CSF WNV IgM/IgG, and IgG ganglioside panel and negative toxoplasma studies. She received IVIG given her presentation with mild improvement in her symptoms. 

Her rapid ascending weakness is believed to be secondary to WNV neuro-invasive disease given positive CSF studies, however her multi-system complications were postulated to be secondary to recent CMV infection which appeared to have been rebooted by her immune response to acute WNV infection via cross-reactivity.