What is Cyclospora? Two deaths as US outbreak puts Europe on alert

Two people have died in Michigan from complications linked to cyclosporiasis, an intestinal infection caused by the parasite Cyclospora cayetanensis. They are the first deaths associated with the large outbreak currently affecting the United States, where more than 18,000 cases have been reported since the start of the season, an exceptionally high figure compared with previous years.

Michigan health authorities have said that both victims had serious pre-existing conditions and that dehydration caused by diarrhoea may have worsened their condition. In the state, more than 11,200 cases have been reported, with almost 200 hospital admissions.

What is Cyclospora and how is it transmitted

Cyclosporiasis is caused by a microscopic parasite that can contaminate fresh produce and water. Unlike many intestinal infections, it is not spread directly from person to person: infection almost always occurs through the consumption of contaminated fruit, vegetables or water.

Symptoms include:

• severe, prolonged diarrhoea;
• abdominal cramps;
• nausea;
• loss of appetite;
• fatigue;
• fever in some cases.

Without treatment, the illness can last for several weeks. The main risk is dehydration, which is particularly dangerous for older people, those with weakened immune systems and patients with chronic diseases.

Why cases rise in summer

The increase in infections in the summer months is no coincidence. In the United States, the cyclosporiasis season generally runs from May to August, a period when consumption of fresh produce such as salads, herbs, berries and other raw vegetables increases.

High temperatures and greater circulation of fruit and vegetables also help the parasite spread along the food supply chain. In the US outbreak, investigators are focusing on iceberg lettuce distributed by Taylor Farms, which has already been recalled from the market after being identified as a probable source of contamination.

What about Europe? No major outbreak, but surveillance is being stepped up

At the moment, the European Union is not experiencing a cyclosporiasis epidemic comparable to the one hitting the United States.

According to the European Centre for Disease Prevention and Control (ECDC), cases recorded on the continent are generally sporadic and mostly affect people returning from trips to countries where the parasite is endemic, such as Mexico, Peru, Guatemala and other tropical and subtropical areas. In recent years, only a few outbreaks have been documented in Europe, almost always linked to imported food or infections acquired abroad.

One warning sign comes from the United Kingdom, where between April and mid-July 2026, 67 cases of cyclosporiasis were reported, almost all of them associated with travel to Mexico. For this reason, European health authorities are maintaining heightened surveillance during the summer, when increased international travel and higher consumption of fresh fruit and vegetables can facilitate the importation of new cases.

Why it is being talked about so much right now

The combination of the exceptional outbreak in the United States and the holiday season has put the parasite back in the spotlight. In summer, international travel increases, as does consumption of salads and uncooked foods, along with the chances of exposure to contaminated food and water.

Health authorities therefore recommend a few simple precautions: wash fruit and vegetables thoroughly, drink safe water when travelling, keep food properly refrigerated and see a doctor in the event of persistent diarrhoea, especially if it is accompanied by signs of dehydration or affects vulnerable people.