Michael S. Donnenberg, M.D.
Since mid-August, more than 175 people in 26 states, including Maryland, have been infected with a outbreak of E. coli O157:H7 from fresh spinach grown in California. This outbreak has received a lot of media attention, as this potentially deadly bacteria is usually associated with eating undercooked, contaminated ground beef. What to do? Dr. Michael Donnenberg, an infectious disease expert at the UM Medical Center and professor of medicine at the UM School of Medicine, answers some frequently asked questions about E.coli and this outbreak in the following interview.
What is E. coli?
E. coli is a species of bacteria very commonly found in the large intestine of man and other warm blooded animals. Most strains of E. coli are harmless, even beneficial to the host. However, some strains of E. coli contain extra genes that provide them with the ability to cause disease. One type of disease-causing E. coli produces a potent toxin that can make people severely ill.
What is the definition of an outbreak?
An outbreak is an unusual number of cases of a disease that occurs in a recognizable pattern, for example among people in a certain geographic area or who have consumed a common item.
What ways do people contract it?
People can become infected with disease-causing E. coli by eating contaminated food, drinking contaminated beverages, swimming in contaminated water or coming in close contact with infected farm animals, or infected people. The ultimate source of the disease-causing E. coli is usually the gastrointestinal tract of cattle. The food, drink, swimming water or other sources become contaminated with cattle feces or sewage either directly or indirectly.
What are the symptoms of infection with this disease-causing E. coli strain?
The symptoms often begin with abdominal pain and cramps, which may be severe. Watery diarrhea then ensues, followed in many but not all cases by bloody diarrhea.
What foods could/are likely to contain E. coli contamination?
The most likely source of this disease-causing E. coli strain is contaminated ground beef. However, outbreaks have been linked to many other food items and beverages. Unpasteurized milk and juices are high risk. In recent years there have been many outbreaks linked to produce items such as lettuce and now spinach.
What do you make of the E. coli cases caused by the eating of the contaminated bagged spinach grown in California? How could spinach have been contaminated?
This is the first outbreak due to contaminated spinach, but contaminated lettuce and sprouts have been reported before. The contamination can come from irrigation with contaminated water, run-off from nearby cattle farms, fertilization with contaminated cattle manure, or can occur after harvest.
Is it safe to eat frozen or canned spinach?
Will cooking raw spinach kill E. coli?
It will, but there is danger in handling the raw spinach prior to cooking. For example, the disease-causing E. coli can get on your hands, your utensils, your cutting knives and subsequently be ingested.
Regarding this outbreak, what precautions should people take? For example, should people wash all fresh raw vegetables/salads before consuming?
Produce should always be washed before consumption and care should be taken not to use the same utensils in preparing uncooked foods that have been used with uncooked meat. However, sometimes the contamination is within the plant, not just on the surface and so washing may not be enough. For the current outbreak, specific brands of raw spinach have been identified. If you have one of these brands, it should be discarded immediately.
Any general advice to the average person about the risk of E. coli and how to avoid contracting it?
All ground beef should be cooked until the middle reaches a temperature of 160 degrees Fahrenheit (well done or until the juices run clear). Wash your hands after handling raw meat. It is also important to wash your hands immediately after visiting petting zoos. Never drink unpasteurized milk or juice. Children with diarrhea should not be permitted to bathe in public places.
Are there any people who should take special precautions when eating fresh produce?
We should all follow the same precautions. However, the risk of serious complications is higher in the very young and the elderly.
By Michelle W. Murray
University of Maryland Medical System Web Site Writer