The World Health Organization has declared a global public health emergency because polio is beginning to spread.
It is a move that has never happened before.
For nearly 30 years, there has been a campaign to wipe the crippling virus off the face of the earth.
The effort had been successful, confining polio to just 3 countries last year; Pakistan, Afghanistan, and Nigeria.
This year, there are outbreaks in 10 countries in Asia, Africa, and the Middle East; in countries such as Syria, Israel, Somalia, and Ethiopia.
"There's potential for spread everywhere but fortunately, in many developed countries ... populations are highly vaccinated," says World Health Organization spokesman Gregory Hartl.
The WHO is now urging the governments of Pakistan, Afghanistan, and Nigeria to impose a requirement on all of their citizens to show proof of polio vaccination before being allowed to travel to other countries.