Montgomery County health officials announced Friday that they can’t identify the source of a July E. coli oubreak that killed one person and sickened 79.

Several factors hampered investigators’ efforts to determine where the E. coli o157 outbreak originated, said Bill Wharton, spokesman for Public Health - Dayton & Montgomery County. The investigation is finished, he said.

“This was an extensive investigation that involved many segments of our department,” Wharton said. “It was as thorough and as complete an investigation as we’ve ever done.”

The outbreak was linked to a July 3 customer appreciation picnic at Neff’s Lawn Care in German Twp. More than 300 people attended the event, and many carried in food to share.

Lowell Draffen, a 73-year-old retired school superintendent and Germantown resident, died July 24 of complications related to the infection. Two children, a girl, 4, and a boy, 14, were hospitalized with hemolytic uremic syndrome, an E. coli complication that can lead to kidney failure and in rare cases, death. Both have since been released. In all, 14 people were hospitalized.

Investigators interviewed 117 people about what they ate, and talked to people who brought food about how it was prepared, served and stored during the event.

A statistical analysis of data from 117 interviews of people who attended and ate at the picnic did not conclusively link any of the meat items served to the outbreak, investigators said.

Among the complications investigators faced:

• The picnic occurred July 3, but the first illnesses weren’t reported until July 9. By that time, Wharton said, there were no leftovers from the picnic to test for E. coli.
• Food was provided from multiple sources, including more than 100 side dishes brought by guests. The event hosts prepared hot dogs and hamburgers at the site, and two hogs were roasted off-site and delivered to the picnic site at mealtime.
• Because so many food items from so many sources were involved, “it was not possible to know with certainty the actual conditions and temperatures of food preparation and handling at the event or in the homes of those who brought carry-in items,” said the health department report released Friday.

Investigators interviewed 65 people who were taken ill and 52 who ate food served at the picnic but didn’t get sick. Investigators had to focus on the meat items — plain pork, barbecue pork, hamburgers and hot dogs — because few guests ate the same side dishes, and there was no overall inventory of foods carried in to the picnic, Wharton said.

Investigators also checked the water sources at the picnic site, and inspected the sites where the hogs were slaughtered and roasted. All tested negative for E. coli and other pathogens.

He couldn’t say how many man-hours the department devoted to the investigation or give its cost. That information will likely be included in a final report to be released later this year, Wharton said.

E. coli 0157 is one of seven strains of E. coli that produce a toxin that can be fatal. Though it’s most often associated with improperly cooked meat, it’s also been identified in fruits and vegetables, and can also be spread in water or from person-to-person.

Wharton said the outbreak emphasizes the importance of proper food handling to prevent illness. The Centers for Disease Control and Prevention estimate 48 million Americans get sick with food poisoning every year, 3,000 die, and 128,000 are hospitalized.