Cyclospora is a microscopic parasite that can cause an intestinal infection known as cyclosporiasis. People usually become infected by swallowing food or water contaminated with the parasite. Unlike some foodborne illnesses that begin within a few hours, cyclosporiasis often takes about a week to produce symptoms, which can make the original source difficult to identify.
The most common symptom is frequent, watery diarrhea. Some people also experience loss of appetite, weight loss, stomach cramps, bloating, nausea, fatigue, and increased gas. The illness may improve for a short time and then return, creating a frustrating pattern of recurring diarrhea. Without treatment, symptoms can last for weeks or even longer, especially in people with weakened immune systems.
Cyclospora is associated with fresh produce, particularly when that produce has been contaminated during growing, harvesting, processing, or preparation. It is not limited to one type of food. Past outbreaks have involved various fruits, vegetables, herbs, and leafy greens. The parasite can also spread when an infected person handles food without proper hand hygiene, although direct person-to-person transmission is considered less common because the parasite generally needs time outside the body before it becomes infectious.
Diagnosis usually requires a stool sample. A routine test may not always detect Cyclospora, so patients should tell a healthcare professional about persistent or recurring diarrhea, recent travel, and any foods or shared meals that may be relevant. Several stool samples may be needed because the parasite is not necessarily present in every sample. Testing methods vary, and a clinician may request a specific laboratory examination.
The usual prescription treatment is trimethoprim-sulfamethoxazole, an antibiotic combination. People who cannot take this medication should discuss alternatives with a healthcare professional, since commonly used treatments for some other intestinal parasites may not work against Cyclospora. Drinking enough fluids is important, particularly when diarrhea is frequent. Oral rehydration solutions can help replace water and essential salts more effectively than plain water alone.
Medical advice is especially important for young children, older adults, pregnant people, and anyone with a condition or medication that weakens the immune system. Urgent care may be needed when there are signs of severe dehydration, such as very little urination, dizziness, confusion, extreme weakness, or an inability to keep fluids down. Blood in the stool, high fever, severe abdominal pain, or symptoms that continue to worsen also deserve prompt attention.
Prevention relies on careful food and hand hygiene. Wash hands with soap and water before preparing food and after using the bathroom. Rinse fresh produce thoroughly under running water, even when it will be peeled, and keep ready-to-eat foods separate from raw meat and unwashed ingredients. Washing produce can reduce contamination, although it may not remove every Cyclospora organism. During a suspected outbreak, public health authorities may advise people to avoid particular products or discard food from a named source.
A case of prolonged diarrhea should not be dismissed as an ordinary stomach bug. Cyclospora is treatable, but recognizing the pattern and requesting appropriate testing can shorten the illness and help health officials identify contaminated food before more people become sick.