Most of the stricken are children under the age of two who have not been vaccinated against the disease, WHO said.
The organisation is conducting tests on the remaining 12 suspect cases and has joined with the Syrian Ministry of Health, UNICEF and a number of local organisations to start a project to vaccinate 2.5 million children against polio, measles, mumps and rubella.
Experts attribute the destruction of health infrastructure in Syria and the difficulty of carrying out such vaccine programmes to the emergence of the disease.
The majority of areas outside the control of the Syrian regime are suffering from an almost complete lack of medical care for children, said Noureddine al-Jammal, fifth year medical student at the University of Damascus and a volunteer at a field hospital in Syria's Deir Ezzor.
He attributed this to fierce battles that force the families still in Syria to constantly move from one area to another.
There is also a lack of paediatric medical staff, as attention is focused entirely on treating injured combatants and civilian victims, al-Jammal told Al-Shorfa.
Hospitals and medical officials likewise lack the required vaccines, he said.
"Medical quarantine procedures for children who are suspected of having been exposed to the virus are unfeasible in these circumstances and security situation," he added.
"Small amounts of vaccine were made available in the past few days, and those are necessary to vaccinate all children under the age of five, including those who have received the vaccine in the past, as a precautionary measure followed in such cases," al-Jammal said.
In addition to polio, a myriad of diseases have sprung up in opposition-controlled areas and locations where battles continue to rage between opposition forces and the regular army, said Dr Qassem al-Zein, whose medical relief organisation, the Leishmaniasis Association in Syria, works in co-operation with the WHO in territories outside the control of regime forces.
These diseases include leishmaniasis, a disease transmitted by sand flies, hepatitis and measles, he said.
About a year ago, al-Zein established the Association to combat leishmaniasis and other infectious diseases. The organisation has documented 15 cases of measles and thousands of cases of hepatitis and leishmaniasis in Syria's Homs, Aleppo, Deir Ezzor, Idlib and Damascus.
Syrians "lack access to health services, medicines and vaccines", he said, because the occupation and destruction of hospitals and the persecution of doctors and nurses prevents the latter from carrying out their work.
The incubation period for polio ranges between four and 14 days, Egyptian paediatrician Duha al-Arabi told Al-Shorfa. The disease is contracted nasally and orally, and is transmitted via human waste and contaminated food, in particular milk and dairy products.
"Under the difficult living conditions Syrians are experiencing in some of the liberated and besieged areas, and even in refugee camps, the spread of infection becomes a reality, either by way of the victim himself or a carrier of the virus, since it is possible for a person to carry the virus without being infected with the disease," she said.
"The emergence of these cases at this time is linked to the duration of the Syrian revolution, which has surpassed two years, and consequently many new-borns have not received the required vaccines, rendering them susceptible to the virus," al-Arabi said.
Children usually receive the polio vaccine in five doses between the ages of 45 days and 18 years, she said. The most serious cases "involve the virus reaching the nervous system and damaging the spinal cord, in which case the child becomes hemiplegic".
Upon infection, the paediatrician said, the child must immediately be put in medical quarantine and everything he or she comes in contact with must be continually sanitised.
"Unfortunately there is no cure that leads to full recovery, and medical care is limited to preventing complications with antibiotics to protect uninfected muscles, in addition to a specific diet and rehabilitation through physical therapy," al-Arabi said.