Of the five patients, four also suffered from intestinal problems and renal failure. The five who are infected all had recently been in Germany.

    The patients were infected with enterohaemorrhagic E.coli, or EHEC, a particularly deadly strain of the common bacteria found in the digestive(消化) systems of cows, humans and other mammals.

    The outbreak has hit at least eight European countries but virtually all of the sick people either live in Germany or recently traveled there.

    Medical authorities appeared no closer to discovering either the source of the infection or the mystery at the heart of the outbreak: why the unusual strain of the E. coli bacteria appears to be causing so many cases of hemolytic uremic syndrome, which attacks the kidneys and can cause seizures, strokes and comas.

    Earlier this week German researchers showed that Dutch cucumbers were not the cause of the contamination.

    "It is essential to quickly find the source, as long as that is not found, the contamination can spread. It's a very aggressive bacteria and many people are seriously ill," a RIVM spokesman said.(本文由在线英语听力室整理编辑)