An examination of sewage water taken from the Reading Power Station in Tel Aviv found traces of type-2 polio virus, that may be violent.
Health Ministry officials told Ynet the examination found the remainders of a weakened polio virus that was used to immunize several people in the Tel Aviv metropolitan area.
The virus was supposed to leave immunized people's bodies within a short while, but for unknown reasons it transformed into several mutations, continued to reproduce and eventually left their bodies through their fecal waste and reached the sewage system.
According to the Health Ministry, those who have not been vaccinated against the polio virus are in danger of contracting the disease – should they come in contact with people carrying the mutant virus, or with sewage water. About 95% of Israelis have been immunized against the disease, they said.
The Health Ministry said there was no fear of a polio outbreak.