A segmented dsRNA (reovirus).

- Most important global cause of infantile gastroenteritis.- Major cause of acute diarrhea in the US during winter, especially in day care centers, kindergartens.

- Villous destruction with atrophy leads to ↓ absorption of Na⁺ and loss of K⁺.

CDC recommends routine vaccination of all infants except those with a history of intussusception or SCID.