Researchers with the U.S. Department of Agriculture’s Agricultural Marketing Service have isolated Escherichia (E.) coli O157:H7 from a variety of pest flies in leafy green fields planted up to 180 meters away from cattle feedlots.  Among most fly species captured on sticky traps at leafy green farms, 22.3-29 flies per 1,000 flies carried E. coliO157:H7.

In 2018, Shiga toxin-producing E. coli O157:H7 in romaine lettuce was responsible for an outbreak that sickened 62 people in 16 states, of whom 25 were hospitalized.

The researchers noted that more work is needed to determine the human health risk posed by these flies and whether they are capable of contaminating leafy greens and causing a foodborne illness outbreak.