FOOD SAFETY
Detecting Cyclospora in Food:
FDA’s Success with a New Method during Outbreaks
by Robyn Randolph, senior specialist, Food Laboratory Accreditation
Protecting our food supply and preventing
human illness is a core mission for
the US Food and Drug Administration
(FDA). In summer 2018, FDA led several
investigations into multistate outbreaks of
Cyclosporiasis, an intestinal illness caused
by the parasite Cyclospora cayetanensis that
sickened hundreds of people. Luckily,
a newly-developed FDA food testing
method allowed investigators to identify
the pathogen in food or food articles,
and remove implicated product from
shelves quickly.
Public Health Significance
C. cayetanensis is not a newly emerging
threat, as outbreaks have been associated
with the parasite for years. However, both
sporadic case reports and outbreaks of
Cyclosporiasis are increasing based on
surveillance data from the US Centers
for Disease Control and Prevention
(CDC). These increases could be due to
improvements in surveillance methods,
better diagnostic testing methods for
human illness, or actual increases in
illness due to yet-unknown factors.
Whatever the reason for the reported
increase in Cyclosporiasis cases, FDA’s
development of a new Cyclospora food
testing method was timely given last
year’s large-scale outbreaks. Having a
method to confirm the parasite’s presence
in food commodities helps identify
potentially contaminated products and
hasten their removal from commerce.
method for detection of C. cayetanensis
in fresh produce such as leafy greens
and berries. The Parasitology Program
conducted a multi-laboratory validation
to ensure the method’s accuracy and
reproducibility. The method was published
in 2017 in FDA’s Microbiological Methods
& Bacteriological Analytical Manual
(BAM) 1 , which lists the FDA’s preferred
methods for pathogen detection. All
seven FDA Office of Regulatory Affairs
(ORA) Human and Animal Food (HAF)
laboratories can conduct the Cyclospora
analysis, with an ongoing expansion to
state laboratories.
Cyclospora Outbreaks
in Summer 2018
Summer 2018 was a busy season with two
large multi-state outbreaks attributed to
C. cayetanensis.
In June 2018, FDA 2 and CDC 3 worked
together on a Cyclosporiasis multi-state
outbreak in four states. As of September
2018, the CDC had been notified
of 250 laboratory-confirmed cases
of Cyclosporiasis from four states.
Epidemiologic evidence pointed
to pre-packaged vegetable trays.
Unfortunately, traceback analysis
was unable to determine the specific
component of the vegetable tray that was
responsible for the contamination.
In July 2018, an even larger outbreak
surfaced, with 511 laboratory-confirmed
cases 4 from 15 states and New York City.
Cases reported consuming salads from a
major fast-food chain. FDA 5 was able to
utilize the newly developed method to
confirm the presence of C. cayetanensis
in an unopened package of salad mix
(romaine and carrots) distributed to
the chain restaurants. Although a
single source of contamination was not
identified, FDA worked with the chain
to stop selling salads in 14 states; the
Validation of the New Method
FDA has not been able to detect Cyclospora
in food since the early 2000s, as the
previous detection method relied on
supplies that are no longer commercially
available. Following large, multi-state
Cyclosporiasis outbreaks in 2013, FDA’s
Center for Food Safety and Applied
Nutrition (CFSAN) created the Foodborne
Parasitology Research Program to develop
a new detection method. The Parasitology
Program worked to adapt and improve a
real-time polymerase chain reaction (PCR)
12
LAB MATTERS Spring 2019
FDA was able to utilize the newly developed method to confirm the presence
of C. cayetanensis in an unopened package of salad mix (romaine and carrots)
distributed to the chain restaurants.
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