Health officials in the United States are investigating a large outbreak of Cyclospora, a tiny parasite that has made thousands of people sick. Most cases are in the state of Michigan. People with Cyclospora infection have severe diarrhoea, stomach pain, and feel very tired. The illness often starts days or weeks after eating contaminated food, so it is hard for people to know what caused it.

Officials believe that fresh fruit and vegetables are the main cause of the outbreak. Investigators are looking at foods such as leafy greens, herbs, onions, and cucumbers, but they have not found the exact food yet.

Because of this outbreak, doctors advise people to wash their hands and rinse fresh produce well. They also ask anyone with diarrhoea that does not stop after a few days to see a doctor quickly.