Some people infected with the microscopic parasite that causes cyclospora infection develop no signs or symptoms. For others, signs and symptoms — which usually begin within two to 11 days of eating contaminated food or drinking contaminated water — may include:

• Frequent, watery diarrhea
• Bouts of diarrhea alternating with bouts of constipation
• Loss of appetite and weight loss
• Bloating, flatulence and burping
• Stomach cramps
• Nausea and vomiting
• Muscle aches
• Fever
• Fatigue — this symptom may last long after the active infection has gotten better
• General feeling of unwellness (malaise)

The diarrhea may end by itself within a few days, or it may last for weeks. If you have HIV or another condition that compromises your immune system, the infection can last for months if not treated.

A one-celled parasite, Cyclospora cayetanensis, causes cyclospora infection. You get it by drinking water or eating food that's been contaminated by a person infected with the parasite.

A person infected with cyclospora passes the parasite in stool. However, unlike some other foodborne parasites, cyclospora doesn't become infectious until days or weeks after it's passed in a bowel movement. So it's unlikely that you can get the infection directly from a person infected with cyclospora, such as a restaurant worker who doesn't wash his or her hands adequately after using the toilet.

Before the 1990s, sporadic cases of cyclospora infection turned up only in people who traveled in developing countries and in those with HIV or another condition that caused a weakened immune system. However, since the 1990s, lettuce, fresh basil and imported raspberries have been implicated in cyclospora outbreaks in the United States and Canada.

In the past, people who traveled in developing countries were more likely to get cyclospora infection. These days, the infection is found worldwide, and anyone who ingests contaminated food or water can get it.

The prolonged diarrhea of untreated cyclospora infection can cause dehydration. If you're an otherwise healthy adult, you can treat dehydration by drinking more fluids. Some people may need to be hospitalized to receive intravenous fluids because they're at higher risk of severe dehydration. Examples include:

• People with other serious illnesses
• Infants and young children
• Older adults