Two deaths in Michigan have put the spotlight back on cyclospora, a microscopic parasite that causes a prolonged and debilitating intestinal illness. The fatalities, linked to complications from dehydration, mark the first deaths in an unusually large US outbreak that has already sickened more than 18,000 people since the season began. Michigan alone has reported over 11,200 cases and nearly 200 hospitalisations.
Cyclosporiasis is caused by Cyclospora cayetanensis, a single-celled parasite that contaminates fresh produce and water. Unlike many foodborne infections, it does not spread from person to person; infection almost always follows the consumption of contaminated fruit, vegetables, or water. The parasite is notoriously resilient, surviving on produce for weeks under the right conditions.
Symptoms and risks
Symptoms typically appear about a week after exposure and include severe, watery diarrhoea, abdominal cramping, nausea, loss of appetite, fatigue, and sometimes fever. Without treatment, the illness can linger for weeks, and the primary danger is dehydration—especially for the elderly, the immunocompromised, and those with chronic conditions. Michigan health officials noted that both deceased individuals had serious underlying health issues, and the diarrhoea likely worsened their condition.
In the United States, the cyclospora season runs from May to August, coinciding with peak consumption of salads, herbs, berries, and other raw vegetables. Investigators have zeroed in on iceberg lettuce distributed by Taylor Farms, which has been recalled as a probable source. The scale of this year's outbreak is exceptional, with case numbers far exceeding previous years.
What does this mean for Europe?
So far, the European Union has not seen a comparable epidemic. According to the European Centre for Disease Prevention and Control (ECDC), cases on the continent are sporadic and mostly linked to travel to endemic regions such as Mexico, Peru, and Guatemala. In recent years, only a handful of outbreaks have been documented in Europe, almost always traced to imported food or infections acquired abroad.
One warning sign comes from the United Kingdom, where 67 cases were reported between April and mid-July, nearly all associated with travel to Mexico. European health authorities are therefore maintaining heightened surveillance during the summer, when international travel and fresh produce consumption increase the risk of imported cases.
For travellers, the advice is straightforward: wash fruit and vegetables thoroughly, drink safe water, keep food properly refrigerated, and seek medical attention if diarrhoea persists, especially with signs of dehydration. The EU's recent focus on heatwave preparedness highlights the broader need for seasonal health planning, and cyclospora is another reminder that summer brings its own health challenges.
While the current US outbreak is a stark reminder of the risks, European health systems are well positioned to respond. The key is vigilance—both for returning travellers and for the food supply chain. As the summer heatwave grips parts of Europe, the combination of high temperatures and increased travel could create conditions for sporadic cases, but no widespread outbreak is anticipated.
For now, the message from health officials is clear: awareness and simple precautions go a long way. The parasite may be invisible, but its effects are anything but.
