More than 1,000 cases of cyclosporiasis have been recorded in Michigan alone over two weeks, signalling a larger outbreak than official national figures suggest. The US Centers for Disease Control and Prevention (CDC) reported 145 cases across 17 states on June 16, but Michigan's surge indicates the true scale is far greater.
What is cyclosporiasis?
Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora. First recorded in 1989 among 55 Brits in Nepal, it is native to tropical regions but increasingly causes non-travel-related outbreaks in developed countries. The infection typically resolves on its own after a few weeks, but symptoms can include explosive diarrhoea, bloating, flatulence, and fatigue.
How is it spread?
People contract cyclosporiasis by consuming food or water contaminated with the parasite. Common sources include fresh produce like salad leaves and fruit, or unclean water. In 2018, outbreaks were linked to prepackaged vegetable trays and fast-food salads. However, health officials have not yet identified the source of the current outbreak. Crucially, the infection cannot be passed directly from person to person.
Current outbreak details
As of July 10, 2026, cases have been reported in at least 17 states, including Illinois, New York, Texas, and Michigan. While no fatalities have occurred, the CDC confirmed 20 patients have been hospitalised. The lag between infection and symptom onset—up to three weeks—makes tracing the source challenging.
What travellers should do
If travelling to affected areas, thoroughly wash all vegetables and fruit, especially leafy greens and raspberries. Michigan's health department recommends cooking raspberries and leafy greens when possible, and removing outer layers of lettuce and green onions. If symptoms like frequent diarrhoea develop, contact a healthcare provider. Untreated, the illness may last from a few days to over a month.
Symptoms to watch for
Symptoms typically appear about one week after infection and include: watery explosive diarrhoea, loss of appetite, bloating with burping and flatulence, extreme tiredness, low-grade fever, stomach cramps, nausea, and vomiting.
