An NPR piece explains how Cyclospora, the microscopic parasite behind a major 2026 outbreak, actually operates once it enters the human body. The article is timely because the US is experiencing its largest-ever Cyclospora outbreak this summer, with cases reported across 45 states and more than 10,000 illnesses in Michigan alone, most linked to contaminated lettuce. Understanding the parasite's biology helps explain why the illness is so prolonged and hard to trace compared with more familiar foodborne bugs.

Cyclospora spreads as dormant "oocysts" so small that around a hundred could fit end to end across a pinhead; these get onto produce via contaminated water, soil or human waste and must mature in the environment for days or weeks before becoming infectious, while resisting chlorine, sunlight and cold. Once swallowed, they pass to the stomach and intestines, where body heat and digestive cues trigger the parasites to emerge, invade the lining of the small intestine, multiply into millions of copies and damage the gut, causing nausea, diarrhoea and poor nutrient absorption that can last weeks or months. Taylor Farms lettuce imported from Mexico has been linked to the outbreak, while North Carolina investigators have also flagged parsley and cilantro as possible sources; antibiotic combinations such as Bactrim can help halt the parasite's replication.