A worker harvests romaine lettuce in Salinas, Calif. (AP Photo/Paul Sakuma)
While the recent outbreak of E. coli infections linked to romaine lettuce has been declared over, Canadian public health officials are still working to determine the cause of the contamination.
Several people in the U.S. and eastern Canada were sickened after eating romaine, with two reported deaths.
I am a food safety expert. Here’s what consumers need to know about E. coli and produce:
E. coli are bacteria that live naturally in the intestines of cattle, poultry and other animals. For the most part, they co-exist with these animals, and hence they don’t become sick.
Most of the E. coli strains associated with humans are harmless, and, in fact, are an important part of a healthy human intestinal tract. However, some E. coli strains are pathogenic, meaning they can cause human illness. Pathogenic E. coli that can cause diarrhea can be transmitted through contaminated water or food, or through contact with animals or people.
There are many different ways that produce can become contaminated. Firstly, in the farmer’s field, it can become contaminated with pathogenic E. coli through direct contact with animal feces.
For example, wild animals, like feral pigs and deer rummaging through farm fields, have previously been found to be linked to cases of illness due to spinach and strawberries, respectively.
In fact, any time produce in the field makes contact with animal feces, it could lead to the contamination of that produce with a pathogen. Contaminated irrigation water, bird feces or improperly composted manure are other potential sources of pathogenic bacteria.
A red-winged blackbird rests on the head of a deer as it looks up from grazing in a sun-drenched farmer’s field in Vermont in 2011. (AP Photo/Toby Talbot)
Once produce is sent from the farmers’ fields to processing plants, there are other potential sources of microbial contamination, including the water used to wash the produce and the equipment used to cut up the leafy greens.
Further along the food chain, at the retail store, if the produce is not bagged, there is also the chance for cross-contamination in the store from raw foods — for example, from cutting boards and counters that have been in contact with raw meat, and which haven’t been properly disinfected between uses.