There are many parasites that can make us sick.  Let’s explore what Cyclosporiasis is, how it affects us, and how to prevent it.  Cyclosporiasis is an infection with the protozoan Cyclospora cayetanensis, a pathogen transmitted by feces or feces-contaminated fresh produce and water.  The protozoan lives out its lifecycle intracellularly within a person’s epithelial cells and gastrointestinal tract. Infection is transmitted through the fecal-oral route, and begins when a person ingests oocysts in fecally contaminated food or water.

Outbreaks have been reported due to contaminated fruits and vegetables.  It is not spread from person to person, but can be a hazard for travelers by being a cause of diarrhea.  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 an infected person, such as a restaurant worker who doesn’t wash his or her hands adequately after using the toilet.

The extent of symptoms varies based on age, condition of the host, and size of the infectious dose.  Symptoms include watery diarrhea, loss of appetite, weight loss, abdominal bloating and cramping, increased flatulence, nausea, fatigue, and low-grade fever.   More severe cases show additional symptoms of vomiting, substantial weight loss, excessive diarrhea, and muscle aches. Typically, patients with a persistent watery diarrhea lasting over several days may be suspected of harboring the disease, especially if they have traveled to a region where the protozoan is endemic. The incubation period in the host is typically around a week, and illness can last six weeks before self-limiting. Unless treated, the illness may reoccur. The more severe forms of the disease can occur in immunocompromised patients, such as those with AIDS or a compromised immune system.

Due to its small size, intracellular habitat, and inability to properly take up many histological stains, diagnosis can be very difficult.  There are tests to confirm diagnosis but they are not standard tests and would only be done after consulting with a doctor to rule out other illnesses.  The four methods that have thus far been established for positive diagnosis include microscopic detection in stool samples, recovering oocysts in intestinal fluid/small bowel biopsy specimens; demonstration of oocyst sporulation; and amplification by polymerase chain reaction (PCR) of C. cayetanensis DNA. Since detection is so hard, one negative result should not discount the possibility of infection: tests involving fresh stool samples over the next few days should also be considered.

In the past, people who traveled in developing countries were more likely to get cyclospora infection. These days, the infection is found worldwide because many fruits and vegetables sold in the US are imported from different countries.  Anyone who ingests contaminated food or water can get it so it is very important to thoroughly wash produce before eating it, especially if it is to be eaten raw.  The Cyclospora outbreak in the US that occurred between June and August of 2013 spanned many states.  It was later proven to actually be two separate outbreaks that occurred around the same time.  One was linked to salad mixes and the other to fresh cilantro, both were imported from Mexico.