Q&A: Tracking the source of stomach bug outbreak

State and federal investigators are trying to figure out the source of a stomach bug that has sickened 372 people in 15 states. Iowa and Nebraska have linked some cases in their states to eating pre-packaged salad mix, but the federal Centers for Disease Control and Prevention and the Food and Drug Administration have said the mix is not linked to all of the cases.

Some frequently asked questions about the infection and the outbreak:

Q: What are cyclospora infections and how do people contract them?

A: Cyclospora infection, or cyclosporiasis, is caused by parasites that are spread when people ingest food or water contaminated with feces. People who are exposed usually become sick after about a week and have bad diarrhea and other flu-like symptoms that can last from a few days to a month or longer if untreated. It's common to feel tired and relapse is possible. It's not generally contagious and can be treated with antibiotics. Deaths from the infection are rare.

Q: Who is usually at risk?

A: People who live or travel in tropical or subtropical countries are most at risk, according to the CDC. The infections are rare in the United States but have been linked in the past to imported fruits and vegetables.

Q: Am I at risk in this current outbreak? How do I know if I have it?

A: You are probably OK if you have not already gotten sick. The CDC reports that most of the illnesses were reported between mid-June and early July. Fifteen states have so far reported illnesses: Arkansas, Connecticut, Florida, Georgia, Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, New Jersey, New York, Ohio, Texas and Wisconsin.

Q: How does the government trace the source of illnesses like this?

A: It takes a lot of legwork and coordination between states and the federal government. Cases are confirmed when a sick person gives a sample to his or her doctor and that sample is tested. If it is positive, it will eventually be reported to a state health department. The states then gather that data and coordinate with the CDC to look for common strains that could link the illness to a specific product. State and federal officials interview the victims and closely question them about what they ate around the time they fell ill — often a difficult task, as it is hard for most people to remember everything they ate over an extended time. That is made even harder in a cyclosporiasis investigation because the illness doesn't show up for a week.

In this outbreak, the Food and Drug Administration says its investigators have been trying to trace the paths of the food eaten by those who fell ill. Food often goes through several stops — potentially in several countries — before it reaches a grocery cart, and the FDA said the process is "labor-intensive and painstaking work, requiring the collection, review and analysis of hundreds and at times thousands of invoices and shipping documents."

The agency said it has a seven-person team in its Maryland headquarters and specialists in 10 field offices across the country working to identify the source of the outbreak.

Q: What can I do to prevent contracting an illness like this?

A: Short of growing all of your own food, it may be unavoidable. All foods — including those labeled local, natural or organic — have the potential to be exposed to safety hazards on the farm, in transit or in the store. Sometimes all it takes is one rogue animal that broke through a fence or one employee who didn't wash his hands to infect food.

What you can do is make sure you practice safe handling and preparation. The FDA recommends always washing hands, utensils and surfaces with hot, soapy water before and after handling food. You should also thoroughly wash all fresh produce before you eat it. Those measures should significantly reduce your chances of getting sick.