German officials Wednesday expressed some optimism that Europe’s E. coli outbreak is finally ebbing. But they also acknowledged two more food poisoning deaths, and warned that more deaths are likely.

As of Thursday, the grim toll from the five-week-old crisis included 27 dead and more than 2,800 ill, 720 of them with hemolytic uremic syndrome (HUS), the serious complication of E. coli infection responsible for 18 of the outbreak fatalities.

After several days during which the investigation focused on bean sprouts as a possible source of the outbreak, German investigators shifted their focus back toward cucumbers. In particular, officials cited a family in eastern Germany that was sickened with the outbreak strain of E. coli O104:H4.  A cucumber contaminated with the same strain was found in the family’s compost pile.

However, investigators cautioned that there is no way to tell whether the family was infected by the cucumber, or vice versa.  The cucumber had been in the compost for about 10 days, from May 19 to May 30, so there was a strong possibility that cross contamination could explain why the bacteria was detected on the cucumber.

At the same time, new circumstantial evidence lent more credence to the theory that sprouts from a farm in Lower Saxony might have been the spark that lit the outbreak fire. One hundred EHEC patients are now known to have eaten in 4 cafeterias and 3 restaurants where the farm’s sprouts were served. In addition, one more farm employee (in addition to 2 others previously identified) may have suffered bloody diarrhea, according to Der Spiegel.

Results of tests from sprouts with a longer growing time (more likely to be connected to earlier batches) are expected Friday.

Is the trail too cold?

David Acheson, a food safety consultant formerly with the U.S. Food and Drug Administration, told NPR News that many signs indicate that German health authorities are “struggling” in their efforts to find the source.

“There’s nothing worse than coming up with one source, and then a second source, and coming back and saying: Whoops! We mad a mistake!'” Acheson said. “It really seems like they’re all over the map.”

Acheson and other experts suggest that German health authorities have relied too heavily on high-tech laboratory analysis of victims and potential sources, looking for genetic matches.  They appear to have pursued that strategy rather than traditional epidemiology, which relies on extensive interviews with outbreak victims, searching for common denominators -one or more foods that have been consumed by all of the cases.

By the time German authorities began investigating, the epidemic had been going on for nearly three weeks, and the contaminated food had either been consumed or discarded, Acheson said.  “They want confirmed evidence,” Acheson said. “But this far out, that can be almost impossible to get.”

An evolved, but not new, strain

Meanwhile, the Wall Street Journal reported that the deadly E. coli strain responsible for the outbreak was first identified 10 years ago, in Munster, Germany.

Alexander Mellmann of the University Hospital of Munster, told the Journal that the genetic analysis may help  trace the epidemic to its source. “Everything we know so far indicates it is an evolved strain,” Mellmann told the Journal.

“If it was completely unknown, we’d struggle a lot more in our effort to fight it.”

The cost of medical treatment

While lives can not be quantified in terms of money, medical costs can give a good picture of how severe the human damage has been thus far. The U.S. Centers for Disease Control and Prevention (CDC) estimates that a single fatal case of E. coli O157 (another Shiga-toxin producing strain of E. coli with similar effects to the one in this outbreak) costs approximately $7 million dollars in medical expenses.

Multiplying that by the number of deaths in this outbreak so far yields an amount of $168,000,000, and that doesn’t include the costly treatment, including kidney dialysis, for the other 671 HUS cases who so far are surviving or medical care for the other 2,000 who are infected.

In legal cases, HUS patients are usually rewarded an average of $3 million in damages, which in this outbreak would amount to $2.36 billion, according to attorney Bill Marler of the food safety law firm Marler Clark, publisher of this site.

International cases

Most of those who have been sickened are in Germany, thought to be the site of exposure, but the epidemic also has affected visitors from 12 other European countries, including Austria, Czech Republic, Denmark, France, Luxembourg, Netherlands, Norway, Poland, Spain, Sweden, Switzerland and the United Kingdom according to World Health Organization (WHO).

Sweden and Denmark have been hit hardest. The former has 31 patients, 15 of them with HUS, a staggeringly high figure compared with the usual 10 percent of E. coli patients who develop this complication.

On Wednesday, the Canadian press reported an Ontario resident was ill with the same, virulent strain, but said he is expected to recover.

In the U.S., CDC is reporting 3 HUS cases, 1 of them confirmed as part of the outbreak, and 1 suspected E. coli case. All of these case patients recently returned from Germany.

CDC has issued an advisory to travelers to Germany echoing the Germans’ warning not to eat sprouts, tomatoes, cucumbers or leafy salads in that country — all are still suspect as possible sources of the epidemic.