Nephropathia epidemica: detection of antigen in bank voles and serologic diagnosis of human infection.

An indirect immunofluorescence test for detection of serum antibodies specific for nephropathia epidemica (NE) has been developed with use of acetone-fixed cryostat sections of the lungs of bank voles (Clethrionomys glareolus) that had been trapped from the NE-endemic area in Finland as antigen. NE antigen was detected as distinct fluorescence in the cytoplasm of alveolar and macrophage-like cells. The 16 patients studied included typical cases from an endemic area, cases from a family outbreak, and cases in a laboratory staff which had had close contact with infected bank voles. Antibodies reacting with antigen in the lung sections developed in all of the patients but they were not found in the preimmune sera of the patients, in the sera of patients with other renal diseases, or in the sera of healthy individuals, with the exception of a member of the laboratory staff who had lived in the endemic area for 20 years. No specific IgM antibodies to NE could be detected. The rise in titer of antibodies to NE was characteristically prolonged, and elevated antibody levels persisted for many years.