Following the latest report of the discovery of the polio virus in southern sewage systems, the Health Ministry announced on Tuesday morning that it would begin ensuring that all Israeli children up to age six will receive vaccinations against the virulent disease.

The announcement came after traces of the virus were found for the third time since April on Monday in sewers in the Negev towns of Tel Sheva, Ar’ara and Shocket. All of the sites where traces of the virus have been discovered are located in southern Israel’s Negev desert.

Public Health Services head Dr. Itamar Grotto told Israel Radio on Tuesday that several thousand children in Israel are not vaccinated against polio, some because their parents refuse on ideological grounds, others because their parents either forgot or were unable to arrive at their appointment.

Tipat Halav, the network of state-sponsored clinics that provides maternal and child health services, has called for all parents to bring their children for vaccination. The Health Ministry urged parents to make themselves aware of the risks of the virus and to check whether their children are protected against it.

Last week, polio virus traces were discovered in the sewers of Kiryat Gat and Ashdod. The Health Ministry also reported traces in the southern town of Rahat.

According to a notification published at the beginning of June on the WHO’s Global Alert and Response webpage, the virus was found in a routine monitoring sample taken from sewage near the southern town of Rahat on April 9. Rahat has a population of 53,000. There have been no reports of paralytic polio infections there.

There have been no cases of polio infection in Israel since 1988, although the virus was detected in environmental samples at other times between 1991 and 2002.

According to the WHO, routine immunization in Israel is estimated at 94 percent, and as a result, the risk for international spread of the disease from Israel was assessed as low to moderate.

Polio is an acute infectious viral disease that, in a small number of cases, can enter the nervous system and destroy motor neurons and weaken muscles. The ravages of polio, which was one of the most notorious childhood diseases until the 20th century, were countered by the introduction of vaccines in the 1960s.

The WHO classifies three countries as being endemic for indigenous spread of polio — Afghanistan, Pakistan, and Nigeria. According to The New York Times, there were just 223 cases of polio worldwide in 2012.

Stuart Winer contributed to this report.