During the past few years, intensive searches for new viruses, using conventional virologic methods and metagenomics, have resulted in the discovery of several new viruses. During the past decade, the family Picornaviridae has grown as the number of recognized genera has increased from 6 to 12 (3, 4) ; the numbers of species, types, and subtypes have increased even more. However, only viruses from 3 genera (Enterovirus, Hepatovirus, and Parechovirus) have been fi rmly established as being capable of causing clinically signifi cant disease in humans. Viruses from other genera (Cardiovirus, Cosavirus, and Kobuvirus) have so far been detected only in noninvasively collected human sample material such as fecal and respiratory samples, and their clinical signifi cance remains to be fully elucidated. (Invasively collected sample material is that from tissues considered sterile, i.e., devoid of microorganisms.)