In some countries of the world, infection appears to be seasonal. The incubation period between acquisition of infection and onset of symptoms averages 1 week. Cyclospora infects the small intestine and typically causes watery diarrhea, with frequent, sometimes explosive, stools. Other symptoms can include loss of appetite, substantial loss of weight, bloating, increased flatus, stomach cramps, nausea, vomiting, muscle aches, low-grade fever, and fatigue. If untreated, illness may last for a few days to a month or longer, and may follow a remitting-relapsing course.
Some infected persons are asymptomatic.
Stool specimens should also be checked for other microbes that can cause a similar illness. The latter approach should be considered only for selected patients who require treatment, have been evaluated by an allergist, and do not have a life-threatening allergy. Based on currently available information, avoiding food or water that may be contaminated with stool is the best way to prevent infection. Reinfection can occur. If epifluorescence microscopy is available, the stained slide can first be examined with this technique and suspect oocysts reexamined with bright-field microscopy.