Hawaii E. coli Outbreak Linked to Lettuce
The Hawaii Department of Health has been investigating an E. coli outbreak on the island of Kaua'i. At least 8 people were sickened, four of whom were hospitalized. After 4 months of investigating the cases, health officials determined that the most likely source of the outbreak is floodwater from a nearby cow pasture, meaning cow manure containing E. coli O157:H7 washed into a lettuce field, got onto some lettuce leaves, and was consumed with the lettuce leaves by at least 8 unsuspecting customers at a restaurant.
A story in the Honolulu Advertiser provides an interesting chronology of events leading to the discovery of the likely source of the outbreak:
The Health Department conducted extensive interviews with each of the known victims. The eight had not stayed in the same place on Kaua'i, had not swum in the same place or been in contact with the same animals. Between them, they had eaten in 37 different establishments.
Health investigators took DNA from the disease organisms in patients, and were able to determine that the strain of E. coli O157 bacteria in all the victims had the same DNA "fingerprint." That suggested there was a common source for the infections. . . .
Investigators focused on food, and studied the menus at each of the 37 Kaua'i restaurants. Because no victims appeared to have contracted the disease outside Kaua'i, it was assumed it must come from some local source.
"It was determined that one item, locally produced lettuce, was common to at least one restaurant eaten at by each case during their probable exposure," said Janice Okubo, public information officer for the state Department of Health.
Investigators then headed out to local lettuce farms, and located one farm — which has not been named — that was situated near a cattle farm. There was evidence of local flooding in the area in late February and early March, which could have carried bacteria from cattle manure from the pasture to the crop. Effler said it is likely that the farm was the source of the contaminated lettuce, but not certain.
Cattle are a natural reservoir for E. coli O157, and when samples were taken from cattle in the region where the farm was located, they were found to have the same subtype of E. coli O157 that infected the eight people in Kaua'i in March.
