The Centers for Disease Control and Prevention is investigating an outbreak of the parasite cyclospora linked to "explosive," watery diarrhea as state health departments report nearly 3,000 cases across 31 states; the CDC said it has confirmed 843 cases and is still investigating more than 1,500.
The parasite causes the intestinal illness cyclosporiasis, and the CDC said the most commonly reported symptom is frequent watery diarrhea with sometimes explosive bowel movements; other symptoms include cramps, nausea, fatigue, loss of appetite, low-grade fever and vomiting.
The Michigan Department of Health and Human Services said it has received 1,562 reports since June 22, and Michigan health officials said 44 people have been hospitalized; most Michigan cases have been in southeast counties including Jackson, Lenawee, Livingston, Oakland, Shiawassee, Washtenaw and Wayne, with Monroe County reporting the most at 215.
A tally of state health department data shows 2,912 cases have either been reported or confirmed nationwide, and the CDC reported 31 states have reported cases and that 86 people have been hospitalized across the country.
Other state counts cited by health departments include New York with 394 cases, Illinois with 141 and Ohio with at least 177 cases; the Toledo-Lucas County Health Department reported 306 cases in its area this past week.
Dr. Natasha Bagdasarian, chief medical executive of Michigan, said the rapid rise in cases in the state is "highly unusual," and state laboratories are working to sequence the parasite's genome to see whether isolates are closely related and point to a common source.
The CDC said it is working with the U.S. Food and Drug Administration and local officials to investigate clusters, and the FDA said it was "actively engaged" with state partners as investigators try to determine whether outbreaks in different states are connected.
The agency has said cyclosporiasis in the U.S. is seasonal and usually peaks between May and August, and past outbreaks have been linked to fresh produce such as basil, cilantro, spinach and berries.
The CDC said it can take days to develop symptoms after ingesting the parasite; in more severe cases infections are typically treated with antibiotics, while most people with healthy immune systems recover on their own in days or weeks, and no deaths amid the recent outbreaks have been reported. The agency advises people to wash fresh produce thoroughly, wash hands and kitchen surfaces, see a healthcare provider if they have symptoms, report positive tests to local health departments and drink plenty of fluids to avoid dehydration.