More polio cases in Syria to be confirmed this week - WHO
* WHO says polio cases expected to spread
* Opposition aid body says polio symptoms found in 58 cases
BEIRUT Nov 25 (Reuters) - The World Health Organization is likely to announce more cases of polio in war-ravaged Syria this week, a spokeswoman said on Monday, after the incurable virus was confirmed this month in 13 children who became paralysed.
"(The outbreak) is expected to spread within the country, which is why we need to vaccinate all Syrian children," WHO spokeswoman Sona Bari said in an email sent to Reuters.
"This week we expect confirmation that there are more cases of polio but I don't have the numbers yet," she said, adding that new cases were a sign "that surveillance is working".
In Syria's first polio outbreak since 1999, the virus has been confirmed in 13 of 22 children who became paralysed in the northern province of Deir al-Zor. Investigations continue into the other nine cases.
The opposition-run Assistance Coordination Unit, which oversees humanitarian relief in Syria, said in a report seen by Reuters that there were now 58 cases of acute flaccid paralysis, a symptom of diseases including polio, in the country.
The report said cases had surfaced in Hama in central Syria and in Aleppo and Idlib in the north, suggesting that the virus was spreading.
Polio is endemic in Pakistan, Afghanistan and Nigeria despite a 25-year-old campaign to eradicate the disease, which can paralyse a child within hours.
Syria's immunisation rates have plummeted from more than 90 percent before the conflict to around 68 percent.
Children living in unsanitary conditions are especially vulnerable to the virus, which spreads via faecal-oral transmission and contaminated food and water.
More than 20 million children are to be vaccinated in Syria and neighbouring countries over the next six months, United Nations agencies say.