Persistence of antibodies specific to West Nile virus in blood of reconvalescents of Volgograd region

AIM: Determine the duration of persistence of IgM and IgG in reconvalescents of West Nile fever (WNF) 1 year after the disease in southern regions of Russia and evaluate effectiveness of PCR method for acute infection diagnostics. MATERIALS AND METHODS: Blood sera of 87 patients with WNF diagnosis was studied for the presence of West Nile virus (WNV) RNA and IgM and IgG by PCR and EIA. Samples of the first sera were collected in 2010 at days 2 - 30 after the onset of the disease, samples of the second sera--at days 5 - 23 and third--264 - 385 days later. RESULTS: During the first 2 weeks of the disease WNV RNA was detected in more than 50% of patients. In all the first sera IgM at titers of ≥ 1:800 were detected. Seroconversion of IgG titers of 4 and more times was observedin 83% (30/36) of patients. In 2011 IgG were detected in 91% of reconvalescents (79/87), IgM--in 57% (50/87), and in 25% (22/87) IgM titers were ≥ 1:800. CONCLUSION: The results obtained give evidence on the necessity of using several diagnostic criteria simultaneously for the confirmation of WNF clinical diagnosis.