What is Cyclosporiasis?
Cyclosporiasis is a parasitic infection in the intestines that can cause symptoms such as watery diarrhea and stomach pain. Cyclosporiasis is most common in tropical or subtropical areas and regions of poor sanitation. The most commonly involved areas for United States citizens are Mexico, Peru, and Guatemala. Most cases of this form of food poisoning develop in people who have traveled to these areas or eaten produce imported from these countries.
What causes Cyclosporiasis?
Cyclosporiasis is an illness of the intestines caused by a parasite called Cyclospora.
How is Cyclosporiasis spread?
People become infected with Cyclospora by consuming food or water contaminated with feces that contains the parasite. Cyclospora needs to be in the environment for about 1 to 2 weeks after being passed in stool to become infectious for another person. Because of this, it is not spread directly from one person to another.
Cyclospora is found in many parts of the world but is most common in tropical and subtropical regions. Foodborne outbreaks have been linked to various types of fresh produce, including raspberries, basil, cilantro, snow peas, and mesclun and romaine lettuce. No commercially frozen or canned produce has been connected to Cyclospora infections.
Cyclospora species are variably acid-fast, round-to-ovoid organisms that measure 8-10 µm in diameter. Cyclospora species exogenously sporulate and have 2 sporocysts per oocyst. Transmission follows ingestion of oocysts in fecally contaminated water or produce. Direct person-to-person transmission is considered unlikely because the oocysts are not infectious when excreted; the oocysts undergo sporulation outside the human host before becoming infective. The median incubation period is 1 week, during which time the organism invades enterocytes of the small intestine.
Cyclospora species are characterized by an anterior polar complex that allows penetration into host cells, but the life cycle of the parasite and the mechanisms by which it interacts with human host target cells to cause disease are poorly understood.
What are the risks of getting Cyclosporiasis?
Your risk may increase if you eat contaminated fresh foods imported from tropical and subtropical areas where the Cyclospora parasite is common.
Imported foods that have been linked to outbreaks of cyclosporiasis include:
- Mesclun lettuce
- Snow and snap peas
- Pre-packaged salad mix
Some people infected with the microscopic parasite that causes cyclospora infection to develop no signs or symptoms. For others, signs and symptoms — which usually begin within two to 11 days of eating contaminated food or drinking contaminated water — may include:
- Frequent, watery diarrhea
- Bouts of diarrhea alternating with bouts of constipation
- Loss of appetite and weight loss
- Bloating, flatulence, and burping
- Stomach cramps
- Nausea and vomiting
- Muscle aches
- Fatigue — this symptom may last long after the active infection has gotten better
- A general feeling of unwellness (malaise)
Diarrhea may end by itself within a few days, or it may last for weeks. If you have HIV or another condition that compromises your immune system, the infection can last for months if not treated.
The prolonged diarrhea of untreated cyclospora infection can cause dehydration. If you’re an otherwise healthy adult, you can treat dehydration by drinking more fluids. Some people may need to be hospitalized to receive intravenous fluids because they’re at higher risk of severe dehydration. Examples include:
- People with other serious illnesses
- Infants and young children
- Older adults
How Do Health Care Professionals Diagnose Cyclospora Infections?
Cyclospora infections are not common in the U.S., so individuals who have been in endemic areas or who have other health concerns (for example, long-term diarrhea, eating imported foods without careful washing) should inform their medical caregivers if they suspect a Cyclospora infection. In turn, medical caregivers need to alert laboratories they suspect such infections so that the stool samples will be tested specifically for Cyclospora parasites. In addition, it is likely other tests will be done to determine if other pathogens or similar parasites like Microsporidia or coccidian Isospora parasites are causing the symptoms.
Labs may need to examine and concentrate samples of stool specimens because only a low number of oocysts are shed into the feces. In addition, special stains (note that acid-fast staining of the parasite is variable), fluorescence microscopy, or PCR tests are used to find and identify the parasites.
What is the treatment for Cyclospora infections?
Cyclospora infection often goes away by itself, and mild or asymptomatic cases require no treatment. For those who require treatment, the best option is oral trimethoprim-sulfamethoxazole (TMP-SMX, also called co-trimoxazole) (Bactrim, Septra) twice daily for seven to 10 days.
For those who continue to have symptoms or have persistent oocysts on stool examination, another seven-day course is usually effective. Sometimes anti-diarrheal medication is recommended, but only under the doctor’s approval. For people with a sulfa allergy, there are few good options.
There are reported cases where nitazoxanide (Alinia) twice daily was successful as an alternate therapy. One small study suggested that ciprofloxacin (Cipro, Cipro XR, ProQuin XR) twice daily for seven days is an option in adults.
However, it has a higher failure rate compared to TMP-SMX. These medications are not approved for routine use in pregnancy. Pregnant women should check with their obstetrician (ob-gyn doctor) before taking any new prescription.
Lifestyle and home remedies
To prevent or treat mild to moderate fluid loss from severe diarrhea associated with cyclospora infection, it’s generally adequate for healthy adults to drink water.
For children and infants, you may want to use an oral rehydration solution, such as Pedialyte. Sports drinks and carbonated beverages don’t offer the right balance of nutrients that children need.
How can Cyclosporiasis be prevented?
When traveling to a country where Cyclospora is found, you can reduce your risk by:
- Avoiding food that has been washed in local drinking water
- Drinking water from a safe source
- Cooked food
- Fruit that you can peel yourself
It can be hard to prevent cyclosporiasis. This is because washing produce does not always get rid of the Cyclospora parasite that causes the illness. You can reduce your risk by:
- Following safe food handling practices for production on a daily basis
- Cooking produce imported from countries where Cyclospora is found
- Consuming fresh produce grown in Canada, especially during the spring and summer months when an increase in non-travel related cases of Cyclospora are reported in Canada.