Traces of the crippling polio virus, discovered last week in Beersheba and Rahat, were found Wednesday in the sewers of Kiryat Gat and Ashdod as well. The Ministry of Health believes that the traces originated in the Bedouin village of Rahat.

The ministry stressed there was no reason for alarm, since the water system was sampled and was found to be uncontaminated. Ministry officials added that the process of vaccinating the entire Rahat population was well underway and would be completed shortly.

According to a notification published on Monday on the World Health Organization’s Global Alert and Response webpage, the virus in Rahat was found in a routine monitoring sample taken from sewage near the southern town on April 9.

Rahat has a population of 53,000. There have been no reports of paralytic polio infections there.

Health authorities are conducting a full epidemiological investigation to detect any potential cases or unvaccinated persons. Similar research is also underway in the West Bank and Gaza.

The director of the WHO’s polio campaign, Bruce Aylward, told The New York Times that due to routine immunization among Israelis and Palestinians, there was little risk of the virus spreading.

“Things usually dead-end there because immunity is so high,” he said.

Initial analysis ruled out the strain being the same as the one affecting the Horn of Africa. 2013 has so far seen six cases of paralytic polio reported in Kenya and Somalia.

However, it does appear to be of the same strain as the one found in early 2013 in Cairo sewage samples, which is similar to another strain currently found in Pakistan and Afghanistan.

“This shows how it can jump from place to place,” Aylward was quoted as saying. “If there’s any sense of complacency about the endgame plan, I hope the world has gotten over it.”

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%, resulting in the risk for international spread of the disease from Israel to be 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.