Abstract
BACKGROUND: Solid organ transplant populations are at increased risk for serious clinical manifestations of West Nile virus (WNV) infection.OBJECTIVE: To monitor liver transplant recipients during the 2003 WNV season in Manitoba and to identify incidence, clinical presentation and serology.METHODS: Serial blood specimens were obtained from adult patients followed at the liver transplant outpatient clinic between May 2003 and October 2003. Studies for WNV infection included immunoglobulin (Ig) G and IgM enzyme immunoassay (EIA), hemagglutination inhibition (HI), plaque reduction neutralization test and reverse transcriptase-polymerase chain reaction.RESULTS: None of the 79 patients had clinical presentations suggestive of WNV infection. On testing of the final serum specimen obtained, 14 patients (18%) had positive IgG anti-WNV by EIA and six patients (7%) had indeterminate IgG anti-WNV by EIA, although all were negative by IgM EIA. Four (20%) of the EIA-positive samples were reactive by HI, but all of these were negative by WNV plaque reduction neutralization test; this is consistent with the presence of non-West Nile flavivirus antibody in these sera. Blood specimens obtained throughout the season from EIA- and HI-positive individuals were uniformly negative for WNV-RNA by reverse transcriptase- polymerase chain reaction. Age, sex, hematology and biochemistry findings, hepatitis B or C virus status, immunosuppressive regimen (cyclosporin or tacrolimus) and pretransplant diagnosis of liver disease were similar for EIA-positive and EIA-negative patients. For the 10 patients with a positive IgG EIA maintained on cyclosporin, the cyclosporin level was 129.1±28.6 µg/L compared with 85.6±36.7 µg/L in 26 patients who were EIA-negative (P=0.002).CONCLUSIONS: False-positive IgG EIA serology for WNV was common in this cohort of liver transplant recipients, and was associated with elevated serum cyclosporin levels.