A one-celled parasite, Cyclospora cayetanensis, causes cyclospora infection. You get it by drinking water or eating food that's been contaminated by a person infected with the parasite.
A person infected with cyclospora passes the parasite in stool. However, unlike some other foodborne parasites, cyclospora doesn't become infectious until days or weeks after it's passed in a bowel movement. So it's unlikely that you can get the infection directly from a person infected with cyclospora, such as a restaurant worker who doesn't wash his or her hands adequately after using the toilet.
Before the 1990s, sporadic cases of cyclospora infection turned up only in people who traveled in developing countries and in those with HIV or another condition that caused a weakened immune system. However, since the 1990s, lettuce, fresh basil and imported raspberries have been implicated in cyclospora outbreaks in the United States and Canada.