KANSAS CITY, Mo., Sept. 6 (UPI) -- Hundreds of children have been hospitalized across the U.S. midwest in recent days from a particularly nasty virus that has some doctors perplexed.
There's been a recent upswing of Enterovirus 68, a rare virus that causes mild to severe respiratory illness.
Children's Mercy Hospital in Kansas City, Mo., has seen more than 450 cases recently, St. Louis Children's Hospital has seen a 50 percent uptick in patients and Rocky Mountain Hospital for Children in Denver has seen numerous cases resembling the rare virus.
Dr. Mary Anne Jackson, division director for infectious diseases at Children's Mercy Hospital told CNN she saw a spike in sick children on Aug. 15.
"It could have taken off right after school started. Our students start back around August 17th, and I think it blew up at that point," Jackson said. "Our peak appears to be between the 21st and the 30th of August. We've seen some leveling of cases at this point.
"It's worse in terms of scope of critically ill children who require intensive care. I would call it unprecedented. I've practiced for 30 years in pediatrics, and I've never seen anything quite like this," she added.
There is no vaccine for Enterovirus 68 and though mostly children have been hospitalized with the disease, adults can contract it as well. Jackson said the most severe cases act like asthma exacerbations.
"The difficulty breathing is a very obvious tip-off sign they need to come into the hospital," she said.