Neuroinvasive St. Louis Encephalitis Virus Infection in Solid Organ Transplant Recipients.

Abstract

In summer 2015, three unrelated solid organ transplant recipients in Phoenix, Arizona, had meningoencephalitis suggestive of West Nile virus (WNV) infection. Testing was inconclusive but was later confirmed as St. Louis encephalitis (SLE). We retrospectively reviewed clinical manifestations, treatment, and outcomes of these transplant recipients. Common symptoms were fever, rigors, diarrhea, headache, and confusion. One patient died 3days after hospitalization. Therapy for the other two patients was initiated with interferon α-2b (IFN) and intravenous IgG (IVIG; IFNplusIVIG in combination). Both patients tested positive for WNV by serologic assay, but SLE virus (SLEV) infection was later confirmed by plaque reduction neutralization test at a reference laboratory. Clinical improvement was observed within 72h after initiation of IFNplusIVIG. SLEV has been an uncommon cause of neuroinvasive disease in the United States. Accurate, timely diagnosis is hindered because of clinical presentation similar to neuroinvasive WNV and SLE, serologic cross-reactivity, and lack of a commercially available serologic assay for SLEV. There is currently no approved therapy for flaviviral neuroinvasive disease. Anecdotal reports indicate varying success with IFN, IVIG, or IFNplusIVIG in WNV neuroinvasive disease. The same regimen might be of value for immunocompromised persons with neuroinvasive SLEV infection.