tokens: In animals , the pooled seroprevalence of anti - WNV IgM and IgG was 90.3 % ( 95 % CI , 84.3 to 94.6 ) and 3.5 % ( 95 % CI , 1.9 to 5.8 ) , respectively , while 20.0 % ( 95 % CI , 12.9 to 21.4 ) had WNV - neutralizing antibodies .