German health officials Tuesday continued to grope for clues to the source of an outbreak of non-O157 E.coli that has killed three German women and sickened hundreds more, many of them hospitalized with potentially deadly hemolytic uremic syndrome (HUS.)

The epidemic of enterohaemorrhagic E. coli (EHEC) has affected mostly women, and most of the victims are in northern states — factors that German health authorities hope will lead them to the source of the pathogen. The public health department reported in Frankfort that all of that city’s case patients had eaten in the same cafeteria. 

The number of reported sick surpassed 400 late Tuesday, and more than 80 were hospitalized with HUS.  While Germany is accustomed to dealing with outbreaks of E. coli and other pathogens, it is highly unusual to see hundreds sickened over the span of two weeks, according to officials at the Robert Koch Institute (RKI), Germany’s equivalent to the U.S. Centers for Disease Control and Prevention.  One RKI official reported called the statistics “scarily high.”

One German report suggested that the source may be fresh vegetables that had been fertilized with liquid manure — manure that could have been infected with E. coli. Officials speculated that women are more likely than men to cook and eat fresh vegetables.  

Like the more common E. coli O157:H7, the EHEC bacteria attacks the intestines, leading to internal bleeding, stomach cramps, diarrhea and, in the worst cases, kidney failure. 

The German outbreak began in mid-May, sickening hundreds of women. One northern state, Schleswig-Holstein, had reported 200 EHEC cases by late Tuesday.

German health officials reported that specimens taken from victims showed genetic strains of E. coli — likely E. coli O104 — that the officials had not seen previously.  While the bacteria behaved similarly to E. coli O157:H7, they did not react to the same antibodies.  Tests continued late Tuesday, and scientists were hoping for some kind of breakthrough today.

About 1,000 E. coli infections were reported in Germany last year, but they affected mostly younger people spread over longer periods of time, officials said.  

Health authorities are especially concerned because they can’t limit or combat the outbreak until they know precisely what has caused it.