(CNN) — A respiratory virus is sending hundreds of children to hospitals in Missouri and possibly throughout the Midwest and beyond, officials say.
The unusually high number of hospitalizations reported now could be "just the tip of the iceberg in terms of severe cases," said Mark Pallansch, a virologist and director of the Centers for Disease Control and Prevention's Division of Viral Diseases.
"We're in the middle of looking into this," he told CNN on Sunday. "We don't have all the answers yet."
Advertisement - story continues below
Ten states have contacted the CDC for assistance in investigating clusters of enterovirus -- Colorado, North Carolina, Georgia, Ohio, Iowa, Illinois, Missouri, Kansas, Oklahoma, and Kentucky.