US health officials have confirmed the country’s largest recorded outbreak of cyclosporiasis, an intestinal illness caused by the Cyclospora parasite. The rise is significant because it has already surpassed the total number of reported US cases for the whole of 2025, while authorities expect the count to increase further as delayed reports are processed.

Since 1 May, the Centers for Disease Control and Prevention has recorded 4,173 laboratory-confirmed domestically acquired cases across 41 states, compared with 1,645 cases in 34 states a week earlier. The infection is commonly spread through food or water contaminated with faeces and can cause prolonged diarrhoea, nausea and stomach cramps; officials are investigating outbreaks including one linked to lettuce.