An E. coli outbreak has sickened at least 22 people in Washington state and Oregon. Oregon Health Authority says the cases are linked to six Chipotle restaurants in the region. Eight people have been hospitalized; no one has died from their illness. Chipotle has closed their restaurants in the region.
Because this outbreak is linked to six different restaurants separated by distance, it makes sense that food from a supplier is the source of the pathogenic bacteria. A Salmonella outbreak at Chipotle restaurants in Minnesota in August 2015 was linked to tomatoes purchased from a common supplier. That outbreak sickened at least 45 people.
We don’t know what food is the source of the E. coli that caused this outbreak. In the past, E. coli outbreaks have been linked to raw sprouts, undercooked ground beef, raw milk, leafy greens, frozen foods, and raw vegetables.
But how do these foods get contaminated in the first place? There are many possibilities for contamination throughout the supply chain.
In the field, foods such as greens and other produce can be contaminated by being watered with irrigation water that contains runoff from farms. Since E. coli bacteria live in the guts of ruminant animals, such as cows and goats, their feces contain the pathogen. Large factory farms can contaminate the ground water. When this water is used to irrigate fields during drought conditions, the vegetables will be contaminated.
Foods can also be contaminated during harvest. Ill workers can contaminate food. People who have diarrheal illnesses can shed E. coli bacteria. Then, if there aren’t enough hand washing supplies, or if employers let their employees work while sick, produce can be contaminated.
Transportation is another area where contamination can occur. Storage containers, trucks, conveyor belts, and cleaning equipment can be contaminated with pathogenic bacteria. A study published in the Journal of Food Research, conducted at the University of Arkansas found that bacteria can attach to reusable plastic containers used for transporting food. Scientists grew E. coli bacteria on reusable plastic containers (RPCs) used to transport vegetables and other foods, then cleaned and sanitized them. They found that biofilms could still form on the containers, which can protect bacteria and cause cross-contamination.
Finally, ill food workers can cause E. coli outbreaks. But since this outbreak is linked to several restaurants, that possibility is remote.
The symptoms of an E. coli infection include severe abdominal cramps, diarrhea that can be bloody and/or watery, a mild fever, nausea, and vomiting. Public health officials are asking that anyone who ate at a Chipotle restaurant in Washington or Oregon from October 14 to October 23, 2015, and has experienced these symptoms see their doctor. E. coli infections can be serious. If treated with antibiotics, the odds increase that these infections will progress to hemolytic uremic syndrome (HUS).
The symptoms of an HUS infection include pale skin, easy bruising, lethargy, little to no urine output, and a skin rash. Anyone suffering from these symptoms should see a doctor immediately. HUS can cause kidney failure, seizures, strokes, and death.