"Out of those 22 being investigated, 10 are now confirmed to be polio type one," the WHO spokesman Oliver Rosenbauer told a news briefing in Geneva on Tuesday.
They are still awaiting results on the remaining 12 suspected cases in Deir al-Zor.
"Of course this is a communicable disease, with population movements it can travel to other areas. So the risk is high for [its] spread across the region," Rosenbauer said.
Meanwhile, Lebanon – which hosts more than 700 000 Syrian refugees – said it would vaccinate all children under five against polio.
Around 4,000 Syrians fleeing the foreign-backed war cross into neighboring countries each day, hundreds of them into Lebanon.
People suffer poor sanitation in the refugee camps.
There is no cure for polio, a highly infectious disease that invades the nervous system and can cause irreversible paralysis within hours.
It can only be prevented through immunization.
SHI/SHI