Went looking for percentage of Enterovirus in Central America.
This is what I found: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3854537/
3% of Central American kids have EV.
68,000 times 3% is 2,040. So, statistically speaking, without testing, 2,040 kids crossed the border with the virus.
Think that is enough to cause the current outbreak?
There are at least 71 enteroviruses other than polio that cause human disease. Only one of them is D-68.
http://en.wikipedia.org/wiki/Enterovirus#Enterovirus_68
No. That's not what that article says. That article says that 3% of Central American kids who presented with flu-like symptoms had an Enterovirus. Not that 3% of all Central American kids had an Enterovirus.
AND, more important, while the 3% had AN Enterovirus, most did not have EV D-68 - the researchers found a "high proportion" of EV-A and EV-B strains. Enteroviruses are common. They're common in Central America. They're common in the U.S. They're common pretty much everywhere. And they typically cause cold/flu-like symptoms. So, the fact that 3% of kids with flu-like symptoms had an enterovirus strain would hardly be surprising, anywhere.