It is interesting that of the four confirmed cases, three developed Hemolytic Uremic Syndrome (HUS), a severe, life-threatening complication of an E. coli O157:H7 bacterial infection. Although most people recover from an E. coli O157:H7 infection, about 5-10% of infected individuals goes on to develop HUS. If 5-10% develop HUS, one would think that the outbreak involving Wendy’s would have some fifty to seventy-five sick people rather than just four.
An article by Brandy A. Lee of the Desert Morning News is below:

E. COLI INFECTED 4 AT MEET IN NORTHERN UTAH
Restaurant lettuce the apparent culprit at June gathering?
The Weber-Morgan Health Department confirmed Monday four people were infected with E. coli bacteria in June following a conference held at Orion Junior High in Harrisville.
Three of those people developed a more severe case of hemolytic uremic syndrome, the health department said.

Based on its own investigation, the department said the likely source of the contamination was iceberg lettuce prepared at a Wendy’s restaurant in North Ogden, which was one of the caterers for the conference held June 27-29.
“What we’re trying to determine is what happened,” said Denny Lynch, spokesman for Wendy’s Restaurants in Denver. “Clearly we are very concerned with this incident.”
The conference was attended by more than 300 people, but only a handful reported getting sick.
The restaurant in North Ogden had a regularly scheduled inspection by the health department on June 27. Health inspectors looked at how everything was being done, from when food was brought in the back door to when it was served to customers. No violations nor suggestions for improvement were made by inspectors, Lynch said.
As of Monday, the health department had contacted 75 percent of those who attended the conference. No other cases among the respondents were confirmed to have E.coli.
Weber-Morgan Health Department director Gary House said in a prepared statement he believes the disease outbreak is over. Transmission of the illness is rare. E.coli has an incubation period of two to eight days, which has lapsed, so the health department believes any additional cases would be unusual, House said.
Wendy’s Restaurants is trying to contact those who were apparently affected by the contaminated lettuce and do what they can for them, Lynch said.
Five other E.coli cases were detected earlier in June by the Bear River Health Department in Cache County. The source of infection in that instance is under investigation.