Michigan's cyclosporiasis outbreak is growing at an alarming rate, with over 1,500 cases reported since June 22. This parasitic foodborne illness, caused by the cyclospora cayetanensis parasite, is spreading rapidly, with a 20-30% daily increase in infections. The incubation period can range from two days to two weeks, and the source of the outbreak remains unknown, making it challenging to predict when the spread will slow. The sickest patients are being admitted to hospitals, while others seek treatment at urgent care centers and primary care doctors' offices. Symptoms include watery and sometimes explosive diarrhea, abdominal pain, nausea, and clinical dehydration. At least 44 people have been hospitalized as of July 10. The parasite is not endemic to Michigan but can infect people who travel to tropical and subtropical regions and eat contaminated food or water. Research suggests that the incidence of cyclosporiasis infections is on the rise globally, possibly due to climate change. Michigan appears to lead the nation in the number of cases, but the true scope of the outbreak is difficult to determine due to limited surveillance data. Local, state, and federal health leaders are working to investigate the surge in cases but have yet to identify a common source. Previous outbreaks have been linked to bagged salad mixes and kits, fresh cilantro, basil, raspberries, snow peas, and green onions. The Michigan Department of Health and Human Services has issued updated recommendations to reduce the risk of infection, including cooking leafy greens and herbs, washing hands and produce thoroughly, and avoiding prewashed bagged lettuce. Washing fruits and vegetables may not completely eliminate cyclospora, and heat is the only definitive way to kill the parasite. Symptoms typically begin two to 14 days after exposure and can last four to six weeks. Treatment with antibiotics, particularly trimethoprim sulfamethoxazol, is recommended for confirmed cases. However, the decision to treat with antibiotics is based on public health recommendations, as most cases are self-limited. People with gastrointestinal symptoms should seek testing and medical advice, but should not expect to leave an initial office visit with a prescription for antibiotics. The testing options involve stool samples examined under a microscope or a molecular test that can identify multiple pathogens. The faster molecular test is more expensive but can return results within a day.
