Image by Rebecca Humann from Pixabay
A history of Cyclospora in fresh herbs, fruit, and veggies is a long one. In fact, the first recorded appearance of Cyclospora in food occurred in raspberries.
With a large Cyclospora outbreak in North Carolina with no known source affecting over 100 people so far and an active FDA investigation, also with a not yet known source, it is a good time to explore a history of Cyclospora in fresh fruit and vegetables.
Let’s discuss common food sources, what exactly Cyclospora is and its complicated life cycles. We’ll dive into how Cyclospora illnesses are diagnosed and discus previous outbreaks. Touching on how commercial operations and consumers alike can help prevent the spread of infections as well as how to identify symptoms of Cyclospora illness.
Cyclospora outbreaks historically increase during the warm summer months. Currently, there are at least four active outbreak investigations. One significant outbreak investigation involves an unknown source in Cary, North Carolina. The other three are active outbreak investigations posted on the FDA’s outbreak investigation webpage
At least 134 people have become sickened with Cyclospora in the city of Cary, North Carolina so far this summer.
Current Cyclospora outbreak in Cary, North Carolina sickens at least 134 people
Reports from the North Carolina Department of Health and Human Services indicate that the investigation has not yet revealed a source. Local news indicates that the agency was looking into three Cary, North Carolina restaurants, however a common source has not been found. A cue that this outbreak may be inked to a common ingredient rather than a common establishment.
What could that common ingredient be?
Technically, any food or drink could become contaminated with Cyclospora by cross-contamination. However, with a history of Cyclospora and fresh herbs, fruits, and vegetables, odds are the source comes from the produce section of the grocery store.
Some produce items are more commonly associated with Cyclospora contamination than others.
The U.S. Food and Drug Administration currently has three separate, active, Cyclospora outbreak investigations in progress. So far, none of these active outbreak investigations have uncovered a source. Each are still categorized as “traceback initiated” status.
Two active Cyclospora outbreak investigations were announced by the FDA on July 31, 2024. One outbreak investigation is associated with 16 illnesses. The other cyclospora outbreak investigation is associated with at least 26 illnesses so far.
No source has been identified in these outbreaks at this time.
A third active Cyclospora outbreak investigation was announced by the FDA on August 7, 2024. This Cyclospora investigation has uncovered two illnesses so far.
No source has been identified in these outbreaks at this time.
A case study looking at a 30 year history of Cyclospora outbreaks confirmed that fresh fruits and vegetables were the most common source of Cyclospora. Some fruits, vegetables, and herbs are more prevalent in historical Cyclospora outbreaks than others.
Fresh herbs, fruits, and vegetables most common sources of Cyclospora
Of the 70 internationally identified Cyclospora outbreaks, 55 were caused by fresh produce.
The top worst offenders include:
However, in many cases, a food vehicle could not be identified. In these cases, not enough overlapping information is available from patient information to narrow down a potential source. Or, in some cases, a food item is indicated but a producer could not be confirmed because not enough diagnostic data could be obtained.
The cyclic nature of the parasite’s life-cycle, the intermittent shedding of oocytes, and the relatively small infectious dose contribute to the likelihood that no outbreak source will be identified more often than a source is discovered.
Cyclospora is a microscopic organism known to cause human illness. Unlike most foodborne pathogens that are often bacteria, or sometimes viruses, Cyclospora is a parasite.
Cyclospora is a parasite
A parasite is an organism that requires a host to survive. Parasites often make the host very sick, however the organism needs its host. So very rarely are parasitic infections deadly.
Like many pathogens, the parasite aims to make the host just sick enough to need care with a method of spreading the illness to others, but not kill the host.
So far, humans appear to be the only known hosts for Cyclospora parasites. These microorganisms can persist outside in the environment. But they require a human host to reproduce and grow.
Humans are the only known hosts for Cyclospora parasites, however infections are not contagious.
Fortunately, due to the unique life cycle of these Cyclospora parasites, infections are not contagious. There is no known human-to-human transmission.
Cyclospora cayetanensis is the most common Cyclospora parasites causing illness. Two other Cyclospora species exist, however they have not been observed as causing illness.
The life cycle of a Cyclospora parasite requires two parts to survive.
One part takes place inside the host. The other requires an environmental phase.
The human phase of the Cyclospora life cycle begins when a person ingests food or water that is contaminated with the parasite. Cyclospora make their way to the small intestine, where the oocysts invade the epithelial cells.
Inside those cells, Cyclospora undergo an asexual cycle or sexual development into macrogametocytes, which later become unsporulated oocysts. Later, these cells release those unsporulated oocysts into the feces (poop). Watery diarrhea helps disseminate those unsporulated oocysts into the environment where they can go on to the next phase of their life cycle.
Once released by the human host, Cyclospora parasites require an environmental phase with certain conditions for resporulation. This cannot happen inside the host body.
After a period of around seven to 15 days at a temperature between 73° F to 77° F, sporulation occurs. It is in this phase that the parasite becomes infectious again.
When the parasite contaminates fresh produce or water and is ingested by the human host, the life cycle restarts.
Cyclospora infections can be tricky to diagnose. Many people do not experience symptoms of Cyclospora illness, and therefore can spread the illness without knowing it. These cases go undiagnosed and do not contribute to the outbreak investigation process.
Even in symptomatic patients, oocysts are intermittently released and often in small quantities at a time. Oftentimes, multiple tests from samples taken over several days are necessary to diagnose this illness. In some cases, no diagnosis can be confirmed. If symptoms align with Cyclospora illness, these illnesses are often categorized as “probable” cases when tracking outbreak cases.
Diagnostic tests require a patient sample. We aren’t talking about blood for this one.
Laboratory analysis is performed on a stool (poop) sample. Most suspected foodborne pathogen screening panels do not include Cyclospora tests. Your doctor must order a specialized test to confirm infection.
The most common laboratory test involves looking at a sample under a microscope. The sample is stained with specific dyes that will allow the analyst to see the microorganism.
Alternatively, an Ultraviolet (UV) Fluorescence microscope is sometimes used for identifying Cyclospora. Oocysts appear blue or green against a black background when UV light is applied because the parasite oocysts are autoflourescent.
Molecular diagnostic methods are becoming increasingly popular for Cyclospora analysis. For example, polymerase chain reaction (PCR) methods are used to identify the parasite’s DNA in stool samples. This test looks for key genes included in the parasite’s DNA unique to that microorganism.
Cyclospora cases transmitted to humans through food have been documented over the past 30 years, with the first occurring in 1995, and the most recent one occurring last summer.
Many Cyclospora outbreaks are not linked to a specific food source by the time the investigation runs cold. In these cases, the investigation is often forced to close without a recall or health department enforcement action. However, there are many outbreaks to discuss over the course of a history of Cyclospora outbreaks.
The first documented case of Cyclospora transmission through food was recorded in 1995. Guatemalan raspberries were linked to a cluster of 45 illnesses in the United States. It was unclear whether the source of the raspberry contamination came from direct human contact through infected farm hands, animals, or indirect human contact through contaminated water.
Throughout the course of the investigation, no environmental samples tested positive for the parasitic pathogen.
Prior to 1995, water was the only known vehicle of transmission for Cyclospora
Prior to this raspberry source, contaminated water was the only known vehicle of transmission for Cyclospora.
The first year Cyclospora infections were associated with a domestically produced food item was in 1997. Basil, grown in the United States, was responsible for 185 illnesses. Before 1997, Cyclospora cases were associated with imported produce from tropical areas where Cyclospora is known to be endemic, associated with travel to those tropical areas, or from contaminated water.
The first report of exported Cyclospora food transmission was in 2001 with Thai basil imported from the United States to Canada’s British Columbia. 17 illnesses were associated with this Thai basil Cyclospora outbreak from produce grown in the United States.
In 2017, a cluster of 1,060 cases of laboratory-confirmed Cyclospora infections were identified. Over half (597 patients) reported no international travel leading up to their illness. No source was identified in this large scale Cyclospora outbreak.
This is a common phenomenon in Cyclospora outbreaks.
2018 was a big year for Cyclospora outbreaks. Several outbreaks involving pre-packaged mixed vegetable trays, including broccoli, cauliflower, carrots, and dill dip.
No specific source was identified, however there was a strong correlation between Cyclospora outbreak patients and pre-packaged vegetable trays.
A cluster of 511 laboratory-confirmed Cyclospora cases spanning 15 states was linked to a fast food chain’s romaine lettuce and carrot salads. The establishment used a fresh cut processor company for those items.
An outbreak involving 2,409 Cyclospora illnesses was reported in 2019. These cases spanned several restaurants and event clusters. While around 10% of patients indicated consuming fresh basil imported from Mexico, the majority of cilantro and basil implicated was grown domestically.
A multi-state Cyclospora outbreak with 701 cases was associated with salad mixes containing iceberg lettuce, carrots, and red cabbage. The same fresh produce company responsible for the 2018 multi-state Cyclospora outbreak associated with salads was also implicated in this outbreak.
In 2021 there were 1,020 confirmed Cyclospora cases with no history of international travel. In the same year, two separate outbreaks linked to leafy greens were identified. One outbreak involved 40 illnesses. The other involved 130 illnesses.
A multi-state Cyclospora outbreak involving 210 reported cases spanning 22 states across the country was identified in 2023. This resulted in 30 hospitalizations. At least 20 of those cases were associated with broccoli.
No specific source could be identified before the end of the outbreak, so no recall was initiated.
Preventing Cyclospora infections starts at the source. Produce growers and producers are the first step in preventing Cyclospora contamination. However, consumers can also incorporate safety practices of their own to prevent Cyclospora infection.
Worker hygiene, workplace sanitation, and clean irrigation water are the most important aspects of controlling an illness that is spread through human feces or sewage.
Providing appropriate bathroom and handwashing facilities has historically been a problem for workers in the field. Sadly, when nature calls, you have to answer. If workers do not have access to a safe place to do their business and clean up, crops could be potentially contaminated.
Employees should be educated in food safety practices, proper handwashing techniques (and frequency), and information on the symptoms of Cyclospora infections so they can self-report if necessary.
Irrigation water should be tested and treated as needed to prevent the spread of Cyclospora parasites and other harmful pathogens.
Consumers can take the next step in preventing the spread of Cyclospora illness.
Washing produce before eating it and frequent handwashing activities are a starting point for preventing foodborne illness. When it comes to Cyclospora, ensuring that water sources are clean and safe is that extra step to helping protect yourself and your family from foodborne infection.
Understanding how Cyclospora parasites are spread can make a big difference.
Unlike bacteria and viruses, Cyclospora parasites are fairly resistant to sanitizers.
Where chlorine and other antimicrobial chemical treatments can kill harmful pathogens, they are not effective on Cyclospora. This complicates things.
In countries or regions where Cyclospora parasites are naturally occurring, other forms of treatment must be used on irrigation waters. Where traditional sanitizers fail, there are modern options that are more successful.
Microfiltration, ozone treatment, or UV treatments have been successful at effectively decreasing populations of Cyclospora microorganisms in irrigation waters.
The most common symptoms associated with Cyclospora illness involved diarrhea, with “frequent, sometimes explosive, bowel movements” and fatigue. Most people with Cyclospora infections complain of feeling very tired.
Other symptoms may include:
Some people infected with Cyclospora parasites may not experience any symptoms. For those that do, however, symptoms may seem to go away. Only to return again one or more times. These relapses are very common with Cyclospora infections, in part due to the life cycle of the microorganism.
Without proper treatment, relapses may persist for quite some time.
For situations like this Cyclospora outbreak in North Carolina, where a source has not yet been identified, reporting your illness can help!
Investigators are diligently looking for dots to connect. The more overlapping data they can uncover, the more likely they are to discover the source.
The faster that happens, the faster intervention activities can be initiated. Once intervention activities are initiated, fewer people become sick.
If you have Cyclospora symptoms, reach out to your local health department. Be ready to answer questions designed to narrow down the source of the outbreak.
They will likely ask you what you have eaten in the weeks prior to becoming sick. Be as specific as possible. Include what you ate. Where you ate it. Whether you dined out, brought it home, or prepared food at home. Investigators may also request receipts or access to your grocery shopper accounts/cards to verify purchases and dates.
For Cyclospora illness, investigators will likely ask you about travel, contact with bodies of water, or other environmental risk factors you may have come in contact with.
If you are unsure how to report your illness to your local health department, you have an online option.
The FDA also takes complaints about foodborne illness. Access the MedWatch Online Voluntary Reporting Form online and answer a brief survey.
You will be asked for contact information in case investigators need to follow up with your as well as the same questions mentioned above your local health department would want.
Be as thorough as possible.
If you are impacted by this Cyclospora outbreak, you likely have questions about your rights and potential compensation to cover medical expenses, lost wages, and other burdens associated with foodborne illness.
The Lange Law Firm, PLLC can answer your questions and even some that you may not know to ask.
Navigating the legal system can be complicated. You want advice from a law firm experienced in cases just like yours.
The Lange Law Firm, PLLC can help! As the only law firm in the United States dedicated to representing families with foodborne illness and water contamination lawsuits, you can trust that our team has the experience to recover what you deserve.
An experienced food poisoning attorney knows what information to obtain, the correct approaches to take, and understands your situation.
The Lange Law Firm, PLLC has won millions of dollars in foodborne illness cases from products liability to food contamination.
The Lange Law Firm, PLLC helps hold those liable for illness and injury responsible for their impact on people’s health and lives. We put a great deal of trust in the foods we purchase and consume. We expect that they are safe, free of contaminants and adulterants, honestly represented. When safety practices lapse, people become sick.
Call (833) 330-3663 or email for your free, no obligation consultation. A member of our compassionate team will go over the unique details of your situation to determine if you have a legal case for compensation.
Call today for the first step in getting the justice you deserve.
If you’d like to know more about food safety topics in the news, like “A History of Cyclospora in Fresh Herbs, Fruit, and Vegetables,” check out the Make Food Safe Blog. We regularly update trending topics, foodborne infections in the news, recalls, and more! Stay tuned for quality information to help keep your family safe, while The Lange Law Firm, PLLC strives to Make Food Safe!
By: Heather Van Tassell (contributing writer, non-lawyer)
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