Though health investigators in Hawaii might not find the source of Oahu’s ongoing E. coli outbreak until the outbreak is over, they are still confident they will track it down, state disease investigation branch chief Michele Nakata told Food Safety News Monday. Epidemiologists have found that the nine outbreak victims have some difficulty recalling their food history, which is often one of the first questionnaire routes taken by investigators trying to narrow down potential outbreak sources. (Editor’s note: The Hawaii State Department of Health has since said that only eight cases have been confirmed, while the ninth was found to be an unrelated E. coli infection.) Eight of the victims live on various parts of the island, while the ninth was on vacation from Canada, which suggests the source might be a food product distributed across the island. Given that clue, the investigation team decided to dig deeper into victims’ shopping history by reviewing purchases logged on club cards from various grocery stores. The hope is that if they can compare the purchase histories from each affected household, investigators might uncover a common food item worth tracking down and testing. “It’s pretty labor-intensive and may not result in an answer, but we’re going to pull up all those records and try,” Nakata said. One adult and three children have been hospitalized as a result of their infections. Those three children each developed hemolytic uremic syndrome, a potentially fatal kidney disease associated with severe E. coli infections. The health department has found that two other people on the island had E. coli O157:H7  infections that did not genetically match up with the cluster of nine — nor did they match one another. Investigators are still awaiting lab test results for a potential 10th cluster case. Nakata said the specific genetic pattern of the cluster strain is relatively rare, having only been isolated eight other times on the national epidemiology database, PulseNet. It has most commonly been involved in Hawaiian E. coli illnesses in the past. For the time being, Nakata’s team remains confident they will eventually uncover the source this time around. “The outbreak is concerning to us,” Nakata said. “Even if we can’t confirm the source until after the fact, it gives us a chance to make sure it doesn’t happen again.”