The World Health Organization (WHO) Tuesday confirmed a polio outbreak in war-torn Syria, which has been free of the disease since 1999.
The United Nations' health body reported 10 cases of the crippling disease and said another 12 cases, reported two weeks ago, were still being investigated.
Most of the 22 who were tested are babies and toddlers.
They were all stricken with acute flaccid paralysis, a symptom of a number of diseases, including polio.
"Out 10 of those cases, they've isolated wild polio virus type one," the WHO's anti-polio division spokesman Oliver Rosenbauer said.
"The other 12 are still being investigated," he added, saying test results were expected in coming days.
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Before Syria's civil war began in 2011, around 95 percent of children were vaccinated against polio. The UN estimated around 500,000 had not been immunized in the past two years due to the war.
The current cases of the disease were found to be centered in the northeastern province of Deir Al Zour, where all those affected were under the age of two.
"There are no additional 'hot' cases that we know of. Of course disease surveillance is now ongoing across Syria and neighboring countries as well, to look for other acute flaccid paralysis cases," said Rosenbauer.
"This is a communicable disease, and with population movements it can travel to other areas, and so the risk is high of a spread across the region of course."
As aid agencies and Syrian health authorities waited for confirmation of the polio cases last week, they stepped up their efforts to immunize 2.4 million children against polio, measles, mumps and rubella.
The charity Save the Children called for vaccination ceasefires Tuesday: "'Vaccination ceasefires' would mean pauses in fighting to allow vaccination campaigns to take place across both sides of the conflict."
"Polio doesn't respect conflict lines or borders, so we need these ceasefires to reach all children with vaccines, no matter where they live," Save the Children's President and CEO Carolyn Miles said.
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