Article Summary - Outbreak Investigation of Cyclospora cayetanensis

Food Safety Magazine features an article on Cyclospora cayetanensis and the challenges it poses to the produce industry as the incidence has increased over the past decade.
Here is a summary of that article.

• C. cayetanensis is a parasite that infects the small intestine, causing watery diarrhea with frequent, sometimes explosive, bowel movements. The organism is "transmitted when feces from an infected individual contaminates food or water; however, it is not transmitted directly from person to person because after being shed, the parasite needs time (estimated one to two weeks, at least) in the environment to become infective."
• While the organism is more commonly found in tropical and subtropical regions, "outbreaks of C. cayetanensis infections have been documented since the mid-1990s in the U.S., Canada, Europe, and Australia, and have been associated with the consumption of fresh produce, including raspberries, basil, mesclun, lettuce, snow peas, cilantro, and green onions." Note that these are produce items that are generally more delicate, and thus more difficult to thoroughly wash.

• Outbreak numbers of the past 3 years tend to be large. [data in report goes back to 2013]

2018

Salad Mix - 511 cases in 15 states

Basil - 16 cases in 2 states

Vegetable trays - 250 cases in states

Cilantro - 53 cases in 3 states

2019

Basil - 241 cases in 11 states

2020

Bagged salad - 701 cases in 14 states

• A huge challenge has been difficulty in determining clusters of cases that can be used to identify the source.
• "WGS [whole genome sequencing] is impractical for routine use in cyclosporiasis outbreak investigations for a number of reasons. One reason is that the C. cayetanensis genome is approximately tenfold larger than a bacterial genome; rarely is enough quality DNA obtained from clinical stool specimens or produce samples to sequence the entire parasite genome. Also, unlike bacterial pathogens, this parasite cannot be propagated in the laboratory." However, "FDA has developed multi-laboratory validated methodologies that detect intact oocysts of C. cayetanensis on food matrices such as basil, cilantro, and romaine lettuce, and in agricultural water."
• Identifying the specific food can be difficult. For one, there is generally a 14 day lag between consumption and symptoms. And then diagnosis can be difficult.
• Taking these two factors into account, coupled with the difficulty of finding the organism within the environment or the food, traceback is difficult.
• C. cayetanensis is resistant to most common disinfectants used in the food industry and, therefore, also poses a challenge across the food supply to prevent and eliminate contamination.
• FDA has been conducting increased surveillance of imported produce, especially herbs such as basil and cilantro. FDA has also sampled and tested domestically grown romaine for C. cayetanensis.
• "While additional prevention and control measures are being researched and developed, basic handwashing and hygiene remain critically important in preventing the spread of cyclosporiasis. FDA recently published the "Cyclospora Prevention, Response, and Research Action Plan," which outlines actions necessary to improve prevention, enhance response activities, and fill knowledge gaps to help prevent Cyclospora contamination of foods and prepare for responding to future outbreaks."

Food Safety Magazine  (April / May 2022)
https://digitaledition.food-safety.com/april-may-2022/feature-regreport
Outbreak Investigations of Cyclospora cayetanensis Infections 2013–2020: Progress Made and Challenges Remaining
Recurring outbreaks of cyclosporiasis underscore the need for a comprehensive understanding of how Cyclospora cayetanensis contaminates water and produce

By Stelios Viazis, Ph.D., Fazila K. Shakir, M.H.S., Anne Straily, D.V.M., Adrienne Goodrich-Doctor, Ph.D., Jeffery L. Sumter, Dr.P.H., and Socrates Trujillo, Ph.D.

> REGULATORY REPORT

Cyclospora cayetanensis is a parasitic human pathogen that, when ingested, can cause an intestinal illness called cyclosporiasis, which has been increasing in incidence in the U.S. over the past decade.1,2 While our understanding of this parasite has increased greatly in the past decade, there are still many unanswered questions surrounding this parasite and its recent emergence: How does it make people sick, how does it enter the U.S. food supply, and how are the U.S. Food and Drug Administration (FDA) and its investigative partners responding?

It is helpful to start with what we do know: C. cayetanensis infects the small intestine, causing watery diarrhea with frequent, sometimes explosive, bowel movements. Cyclosporiasis can be treated with trimethoprim-sulfamethoxazole, also known as co-trimoxazole. If not treated, illness may last from a few days to a month or longer. C. cayetanensis is transmitted when feces from an infected individual contaminates food or water; however, it is not transmitted directly from person to person because after being shed, the parasite needs time (estimated one to two weeks, at least) in the environment to become infective.1,3,4 C. cayetanensis is endemic in subtropical and tropical areas worldwide, and people living or traveling in countries where cyclosporiasis is endemic may be at increased risk for infection.5 Due to exposure during their early years, some people from areas where cyclosporiasis is endemic may be infected and shed the parasite without symptoms.

Outbreaks of C. cayetanensis infections have been documented since the mid-1990s in the U.S., Canada, Europe, and Australia, and have been associated with the consumption of fresh produce, including raspberries, basil, mesclun, lettuce, snow peas, cilantro, and green onions.6 The majority of illnesses reported in these non-endemic areas, for which the exposure was identified, were linked to travel or foods imported from endemic areas. Cyclosporiasis is a seasonal illness, and the majority of the cases in the U.S. are illnesses occurring during the months of May through August. Recently, an increase in outbreaks has been seen in non-endemic areas, mostly due to increased international travel, globalization of the food supply, and changes in consumers' dietary habits.5 The increased incidence noted in recent years may also be due partly to changes in diagnostic testing practices in the U.S., such as the increased availability and use of a multiplex molecular assay, which can test for multiple different pathogens simultaneously.7

FDA, in collaboration with the U.S. Centers for Disease Control and Prevention (CDC), as well as state and local public health and regulatory partners, conduct foodborne illness outbreak investigations, including those related to C. cayetanensis infections. Here, the authors review the successes and challenges of identifying and responding to outbreaks caused by C. cayetanensis since 2013, (Table 1) the progress made, the challenges that remain, and what the future holds for addressing such outbreaks.

To access full report - https://digitaledition.food-safety.com/april-may-2022/feature-regreport