By: Eva Frederick

An outbreak of the single celled parasite Cyclospora is sweeping through Texas, with 68 cases of its associated illness, called Cyclosporiasis, reported in in the past month. Of those 68 cases, about half of those occurred in Houston and the surrounding counties, according to the Houston Health Department.

Although the department is currently conducting an investigation into the outbreak, the source of the parasite is still a mystery. On Monday, the Texas Department of State Health Services issued an advisory calling for anyone with symptoms of the parasite — which include persistent diarrhea and bloating, among others — to get tested for the parasite. The advisory stressed that rapid reporting of illness caused by the parasite is key to preventing a large number of cases of Cyclosporiasis this year.

What is the Parasite?

Cyclospora, more specifically, the Cyclospora cayetanensis, is a single-celled parasite found in food or water that causes Cyclosporiasis when ingested by humans. Symptoms of Cyclosporiasis include persistent and sometimes explosive diarrhea, bloating, nausea, vomiting, low-grade fever, weight loss, loss of appetite and other flu-like symptoms. The symptoms can sometimes persist for weeks. During the course of the illness, an infected person may feel better for a few days, and then relapse to their previous condition. The symptoms are often accompanied by a feeling of exhaustion. On the other hand, some people may contract the parasite and show no symptoms.

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How is it Found?

To diagnose a patient with Cyclosporiasis, doctors ask for several stool samples, which they send to a lab. The lab technicians will search for signs of the parasite through a number of methods, both by using a microscope to search for visible oocystes (the form of the parasite that is present in the stool of an infected individual), or through genetic methods such as polymerase chain reaction, or PCR. Multiple stool samples are usually required since the oocytes are not always detectable — one negative result does not always mean a negative diagnosis, according to the CDC. Although Cyclosporiasis infections are not usually life-threatening, it is still advisable to treat the illness with antibiotics as soon as possible since treatment can help shorten the infection period.

To treat Cyclosporiasis, the Center for Disease Control recommends a combination of two antibiotics, trimethoprim and sulfamethoxazole. This medicine is commercially known as Bactrim, Septra, or Cotrim. At this time, there is no alternative treatment available for those with sulfa allergies. The CDC recommends that infected patients with these allergies should discuss other options with their physician. If left untreated, the illness will eventually end after anywhere from a few days to over a month. According the the CDC, Cyclospora is spread through feces, and is not generally transmitted from person-to-person contact, according to the Texas Department of State Health Services. A person who has previously been infected by Cyclospora does not retain any immunity, and so it is possible to catch the disease multiple times.

Because symptoms can appear anywhere from 2 -14 days after contracting the parasite, it can be difficult for health officials to track the outbreak back to a single source. In the past, outbreaks of Cyclospora in the United States have been traced back to fresh produce such as cilantro, pre-packaged salad mix, and raspberries. This, too, makes it difficult to identify what exactly the contaminated food is, since it might be something used sparingly as a garnish or chopped up as a seasoning.

Although Cyclosporiasis can occur year-round, it is most common in the United States in the summer months. The parasite is endemic to several tropical regions, and is more likely to be found on foods that are imported from warmer climates, such as Mexico. In these places where Cyclospora is endemic, it is less likely for people infected with the parasite to show symptoms.

Transmission of the parasite is dependent on the life cycle of the parasite. Unlike the similar common parasite Cryptosporidium, the form of Cyclospora that is passed in stool, called an oocyst, is not immediately infective. This makes fecal-oral transmission impossible. Instead, the oocyst must mature in the environment at specific temperatures until it sporulates, producing two cells called sporocysts. These cells are the infective agent of Cyclospora, and can be transmitted in food or water. Inside cells of the human gastrointestinal tract, Cyclospora undergoes asexual reproduction to form oocysts, which are then forced out of the body in stool.

Cyclospora in Texas

In Texas, the number of cases of Cyclosporiasis has dramatically increased in the last few years. In 2012, there were only 44 documented cases in Texas, but then in 2013 that number jumped to 351. Since then, the number of people affected each year has remained in the triple digits. Last year, 148 cases were reported throughout the state. Many of the cases from 2013, 2014, and 2015 were linked to fresh cilantro imported from Puebla, Mexico. Texas has experienced several separate outbreaks in the past few years, but the current outbreak surpasses the number of people affected in previous outbreaks.

To prevent infection with Cyclospora, health officials recommend that people wash all produce thoroughly before eating, although even washing does not guarantee that the food is free of the parasite. The parasite will be killed by cooking the food at high temperatures. Another way to kill the parasite is by freezing food you suspect might be infected.

“The best thing to do is go to places that you trust, grocery stores you trust or restaurants that you trust,” said Porfidio Villareal, Public Information Officer for the Houston Health Department, in an interview with Houston news network KHOU. “That’s really the best thing you can do.”

If you have any symptoms of Cyclosporiasis — especially diarrhea that lasts for more than a few days — contact your health provider for a test. If a child is affected by Cyclosporiasis, the Texas Department of State Health Services recommends that they be kept out of school until they no longer had diarrhea or a fever. For more information on the biology and treatment of Cyclosporiasis, visit the Center for Disease Control’s cyclosporiasis page. To speak to a food poisoning lawyer.