With more than 1,000 victims confirmed since May 1, the so-called seasonal outbreak of cyclospora in the United States has slowed down, but officials say more people are expected to get sick — and they have not identified the source of the parasite.

Investigators at the Centers for Disease Control and Prevention have identified victims in 40 states, but they are not sure if there is one big outbreak or multiple outbreaks, according to the agency’s most recent update.

As of mid-day Sept. 27, the CDC had laboratory confirmation of 1,054 people with infections from the Cyclospora parasite. The most recent illness onset reported was Sept. 13. However, people who became ill after Aug. 16 might not have been reported yet because of the time it takes between when a person becomes ill and when lab tests are completed and reported.

“At this time, no specific vehicle of interest has been identified, and investigations to identify a potential source, or sources, of infection are ongoing. It is too early to say whether cases of Cyclospora infection in different states are related to each other or to the same food item(s),” according to the CDC update.

“Previous U.S. outbreaks of cyclosporiasis have been linked to various types of imported fresh produce — e.g., basil, cilantro, mesclun lettuce, raspberries, snow peas. Consumers should continue to enjoy the health benefits of eating fresh fruits and vegetables as part of a well-balanced diet. Consumers and retailers should always follow safe produce handling recommendations.”

It usually takes about a week after ingesting Cyclospora parasites for symptoms of cyclosporiasis infection to develop. The parasite infects the small intestine and usually causes watery diarrhea, with frequent, sometimes explosive, bowel movements.

Other common symptoms include loss of appetite, weight loss, stomach cramps/pain, bloating, increased gas, nausea, and fatigue. Vomiting, body aches, headache, fever, and other flu-like symptoms may be noted. Some people who are infected with Cyclospora do not have any symptoms.

If not treated, the illness may last from a few days to a month or longer. Symptoms often may seem to go away and then return one or more times. It’s common for infected people to feel very tired.

(To sign up for a free subscription to Food Safety News, click here.)