	The Centers for Disease Control and Prevention considers a person with JCV infection laboratory-confirmed if: JCV isolated from or JCV-specific antigen or genomic sequences detected in tissue, blood, cerebrospinal fluid, or other body fluids; 2) equal or more than 4-fold change in JCV-specific neutralizing antibody titers between acute and convalescent samples; or 3) JCV or LACV IgM antibodies in serum with JCV-specific neutralizing antibodies equal or more than 4-fold higher than LACV-specific neutralizing antibody titers in the same specimen or a later specimen.