Cyclospora outbreak at Union College Commencement 2019

Charlotte Mineo, Sci/Tech Editor

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Watery diarrhea, cramping, nausea and prolonged fatigue are several symptoms of a cyclospora infection according to the Center for Disease Control (CDC) Cyclosporiasis Provider Fact Sheet. Several members of the campus community fell ill this summer after contracting cyclosporiasis, the infection caused by cyclospora, at a luncheon following commencement. Other individuals got sick after eating at Dutch Hollow in the days following commencement. The Union College Communications Office sent a campus-wide email on August 7 to update students, faculty, and staff on the outbreak.

As of July 23, 2019 more than 580 cases of cyclosporiasis had been verified by laboratories and reported to the CDC. Nation-wide, 38 individuals were hospitalized, but no deaths have been reported. The August 7 email from the Communications Office explains that the outbreak on campus was caused by fresh basil imported from Mexico. A total of 107 individuals across New York fell ill after consuming this produce, which was imported by Siga Logistics de RL de CV of Morelos, Mexico.

Cyclospora is scientifically known as Cyclospora cayetanensis. The single-celled parasite infects the linings of human intestines, and is therefore referred to as a coccidian protozoa. Cyclospora is transmitted by humans, some of whom can host the parasite without displaying symptoms. The CDC-Biology page on Cyclospora explains that the disease is transferred from infected people to their environmant as oocysts, thick-walled cyclospora cells that are very difficult to destroy.

In order for a cyclosporiasis infection to spread an infected person must shed a cyclospora oocyst in their stool. These oocysts are then transferred to fresh produce, either through contact with water contaminated by cyclospora, or by direct contact. The oocysts remain dormant on the food and until they sporulate, which allows some cells within the oocyte to prepare for germination and a new cycle of infection.

The need for sporulation prevents transmission of cyclospora directly from one individual to another. The Food and Drug Administration (FDA) explains it takes several days to weeks for an oocyte to sporulate and become infectious. Because the oocysts are so hardy, the FDA reminds consumers that rinsing or washing produce is unlikely to remove cyclospora.

In an interview with the FDA research microbiologist Dr. Alexandre da Silva explained that cyclospora can be very difficult to detect because very few organisms may be found on a piece of produce. Those that are present are not evenly distributed. Therefore, the parasites cannot be identified using a microscope. Instead, the CDC developed a method to rinse several cyclospora from produce and identify the organism using a polymerase chain reaction (PCR).

The PCR primers are designed to specifically amplify cyclospora DNA, making the test highly specific. Since the test generates millions of extra copies of a specific region of the original cyclospora DNA, relatively few organisms are needed for the test to work.

As of September 2018, the test had been validated, but could only be performed by a handful of laboratories.

Options for preventing cyclospora infection are limited. The CDC recommends avoiding contaminated produce in the first place, but that is only possible after an outbreak has been identified. Adequate hand-washing, and good food-safety procedures can also help minimize the spread of disease. Temperatures above 65 degrees Celsius have been shown to kill the parasite, making cooked produce safer.

New detection methods may be able to detect cyclospora more quickly in the future, helping to minimize outbreaks before more individuals fall ill.