Abstract
Virus particles resembling reoviruses or orbiviruses were found in the faeces of 40 of 73 patients under 6 years of age with acute gastroenteritis and in faeces of only two babies among 31 patients under 6 years admitted to hospital with other diagnoses. In morphology the particles resemble orbiviruses more closely than reoviruses, but differ in appearance from the orbiviruses in having a smooth, circular outline with a well marked continuous rim as seen in negatively stained preparations. They appear not to be serologically related to reovirus types 1, 2, or 3 and may be members of a new group.