Parents in Israel are being urged to take their children for a polio booster after the virus was discovered in sewage.
So far there have been no reported clinical cases.
The virus was found in a treatment plant in the south and then detected in the north, indicating that it had spread throughout the country.
Israel already immunises children against polio but the new campaign is focused on parents giving their children an extra boost of protection.
Israeli President Shimon Peres has backed the effort and revealed that one of his children had contracted the disease.
“In my family one of our children was a victim of polio. It was when he was eight months old, there was an epidemic (of Polio) in Israel. I do not wish it upon anyone to have to go through three days and three nights like that,” Peres said.
In Somalia, there have been 105 recorded cases this year and the UN is warning of a severe outbreak. Most of the cases are in areas controlled by the extremist group al-Shabab.
The World Health Organisation is trying to eradicate polio. It is now only considered endemic in three countries – Afghanistan, Nigeria and Pakistan.
Polio is highly infectious and is exacerbated by poor sanitation and a lack of clean water.