Saffold virus (SAFV) was discovered by Jones et al. in 2007 by sequence-independent genomic amplifi cation of virus isolated from a fecal sample (6) . The sample had been obtained in 1981 from an 8-month-old child with fever of unknown origin. The genetic sequence of the virus indicated that the virus belonged to the species Theilovirus of the genus Cardiovirus, which contains 3 other members: Theiler's murine encephalomyelitis virus (TMEV), Vilyuisk human encephalomyelitis virus (VHEV), and Thera virus. In mice, TMEV is capable of causing infection in the central nervous system, and some variants of this virus cause a persistent infection and even multiple sclerosis -like disease (7) . VHEV was isolated in the 1950s from cerebrospinal fl uid (CSF) from a patient with Vilyuisk encephalomyelitis, a progressive neurologic disorder that occurs in indigenous populations of an isolated part of eastern Siberia (8) . However, the correlation between VHEV and Vilyuisk encephalomyelitis is still uncertain because VHEV has been isolated by multiple passages in mice and thus may represent a highly divergent strain of TMEV. Thera virus (previously named Theilerlike rat virus) has been isolated from rats, but the clinical signifi cance of infections with this virus is unknown (9, 10) . The genus Cardiovirus also contains a second species called encephalomyocarditis virus. Only 1 serotype is known, and it is capable of causing encephalitis and myocarditis in various animals (11, 12) .