Experts from the World Health Organization (WHO) said that a highly infectious new strain of E.coli bacteria, which is causing a deadly outbreak of food poisoning in Germany and other countries, is a never-before-seen mutation.

According to WHO, the outbreak has so far killed 18 and made more than 1,614 others ill in at least 10 European countries. Meanwhile two U.S. travelers were also infected likely from eating salad greens in northern Germany, said the U.S. Centers for Diseases Control and Prevention.

All these cases except two are in people who reside in or had recently visited northern Germany during the incubation period for the infection or at least had contact with a visitor from northern Germany.

In addition to Germany, the center of the outbreak, cases have also been reported in several countries including Switzerland, Poland, the Netherlands, Sweden, Denmark, the United Kingdom and the USA. Essentially all affected people had been in Germany shortly before becoming ill.

This E.coli is a new strain of bacteria that is highly infectious and toxic. It is closely related to another E.coli strain, which has previously been found in Africa and is known to cause serious diarrhea, said the scientists at the Beijing Genomics Institute in Shenzhen city in southern China who are collaborating with colleagues in Germany.

The scientists said the outbreak is thought to come from vegetables, and carried genes that made it resistant to several classes of antibiotics.

The E. coli pathogen has been identified on cucumbers imported from Spain, but it is unclear if they were contaminated there, during the transport or in Germany.

Meanwhile, fresh vegetables from the European Union have been banned in Russia and the country's chief medical officer said such produce will be seized. Spain is threatening to seek compensation from the European Union for lost vegetable sales.

Business has dropped 50 percent on Monday and Tuesday after authorities warned Germany people against eating cucumber, uncooked tomatoes and lettuce in response to the deadly outbreak of E.coli bacteria, a shop owner Maher Abdel Nour told Global Post.

Spanish farmers told Reuters that lost sales resulting from the crisis are costing them 200 million euros ($285 million) a week, and could put 70,000 people out of work in a country which already has the highest unemployment rate in the European Union.