New, and staggering numbers from the German E. coli O104 outbreak: 17 dead, 470 with hemolytic uremic syndrome, 1,534 sick.

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.

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

German authorities initially pointed to cucumbers from Spain after people in Hamburg fell ill after eating fresh produce. After tests of some 250 samples of vegetables from around the city, only the three cucumbers from Spain and one other of unknown origin tested positive E. coli.

But further tests showed that those vegetables, while contaminated, did not cause the outbreak. Officials are still warning all Germans to avoid eating raw cucumbers, tomatoes or lettuce.