The Centers for Disease Control and Prevention (CDC) are investigating a nationwide outbreak of cyclosporiasis that has resulted in more than 800 confirmed cases across the United States, with an additional 1,500 cases under review for possible links to the same outbreak.

Health officials have not yet identified the exact source of the contamination. However, fresh fruits and vegetables remain a major focus of the investigation because the parasite Cyclospora is commonly spread through the consumption of contaminated produce.

The infection affects the digestive system and can cause symptoms such as persistent watery diarrhea, frequent bowel movements, stomach cramps, nausea, loss of appetite, fatigue, and dehydration.

Leafy greens among foods being investigated

While no specific food has been confirmed as the source of the outbreak, health authorities in Michigan, one of the states reporting a significant number of cases, are investigating whether lettuce and other leafy greens may be connected to the infections.

Previous outbreaks of Cyclospora have been linked to a variety of fresh products, including raspberries, basil, cilantro, green onions, peas, lettuce, salad mixes, blackberries, watercress, mangoes, and other fresh vegetables.

Experts say contamination can occur when produce comes into contact with water or soil contaminated with human waste, including through unsafe irrigation practices.

How does cyclosporiasis spread?

Cyclosporiasis is caused by the parasite Cyclospora cayetanensis, which enters the body when people consume contaminated food or water.

The infection is not typically spread through casual person-to-person contact. Instead, it is most often associated with eating raw or lightly processed produce that has been exposed to the parasite.

So far, health officials have not found evidence linking the outbreak to commercially frozen fruits and vegetables, cooked foods, or peeled fruits.

Cooking food at an internal temperature of at least 158°F (70°C) can eliminate the parasite and reduce the risk of infection.

Symptoms and treatment

Symptoms of cyclosporiasis usually appear about five to seven days after consuming contaminated food.

Common symptoms include severe diarrhea, abdominal cramps, nausea, fatigue, and dehydration. In some cases, symptoms may come and go for weeks if the infection is not treated.

Doctors can diagnose the illness through laboratory testing of a stool sample. Treatment typically involves prescription antibiotics, and health experts recommend seeking medical attention if diarrhea lasts several days or signs of dehydration develop.

Public health officials recommend taking extra precautions when handling fresh produce:

• Wash hands with soap and water before preparing food and after using the restroom. Alcohol-based hand sanitizers do not eliminate Cyclospora.
• Rinse fruits and vegetables thoroughly under running water before eating them.
• Wash cutting boards, knives, and food preparation surfaces regularly.
• Remove the outer leaves of lettuce before consumption.
• Peel fruits and vegetables when possible.
• Rewash packaged salads, even if the label says they have been pre-washed.

The CDC continues investigating the outbreak to determine its source and identify any specific foods responsible for the infections. Consumers are advised to monitor official health updates, especially if they develop gastrointestinal symptoms after eating fresh produce.