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Poliomyelitis strain spreads to China: Is U.S. at risk?

Poliomyelitis remains threat in many countries. This undated photo shows polio patients are in Sierra Leone. World Health Organization

(CBS/AP) Think poliomyelitis is a thing of the past? Polio is still a threat in several countries, including Afghanistan, India, Nigeria, and Pakistan - and the World Health Organization is warning that a "dangerous" strain of polio has spread from Pakistan to China.

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A genetic link has been confirmed between wild poliovirus type 1 (WPV1) detected in China and a strain circulating in Pakistan, the organization says. In the past two months, there have been seven confirmed cases involving the WPV1 strain detected in China's Xinjiang province, which borders Pakistan, according to the organization.

WHO spokesman Oliver Rosenbauer says type 1 is more dangerous than type 3 because it is more likely to cause paralysis and spreads more easily. Type 2 polio has been eradicated.

The global health body says countries should strengthen their disease surveillance systems and travelers to Pakistan should be vaccinated against polio.

Polio is a crippling and potentially fatal infectious illness. It spreads through food and water and from one person to another via the fecal-oral route - meaning contact with the stool of an infected person. There is no cure, but there are effective vaccines.

There is no known risk of catching wild polio virus in the U.S., but the CDC says the disease remains a risk to travelers to certain countries. Anyone heading to one of these countries should first check with a doctor to review his/her polio vaccination status.

The World Health Organization has more on poliomyelitis.