Explosive Diarrhea – From Leafy Greens
EXPLOSIVE DIARRHEA – FROM LEAFY GREENS?
Is even lettuce unsafe?
By Allan W. Maynard, - August 2026
OK – so the headlines use the term EXPLOSIVE DIARRHEA which certainly gets our attention. But from lettuce and other leafy greens? These are supposedly at the top level for healthy eating. But even this assumption can be wrong if there are insufficient sanitation protocols.
I can recall my mother teaching me at an early age about food safety – mostly from the handling of meat and fish from initial preparation to the final cooking to the proper temperature, paying attention to best before dates, washing up after preparation, avoiding cross contamination and more. Of course, we learned to wash produce before using but a quick rinse under the tap seemed to be enough. We now know we may need more rigor.
Here is a summary of the current outbreak of cyclospora and other similar outbreaks.
OVERVIEW – ILLNESSES FROM FOOD
Aside from chemical contamination which I have covered before, the 3 main causes of illness in foods are: bacteria, viruses and parasites. For the most part, cooking food properly eliminates the risk from all of these.
Bacteria are single-celled microorganisms that can multiply rapidly under favorable conditions, especially in the "danger zone" between 4°C and 60°C (40°F–140°F). While many bacteria are harmless or beneficial, some can cause serious foodborne illnesses – from diarrhea, vomiting and even kidney failure.
Common foodborne bacteria include:
- Salmonella – Found in raw poultry, eggs, meat, and unpasteurized milk.
- Escherichia coli (E. coli O157:H7) – Often associated with undercooked ground beef, raw vegetables, and contaminated water.
- Listeria monocytogenes – Found in ready-to-eat meats, soft cheeses, and unpasteurized dairy products.
- Campylobacter – Commonly found in raw poultry and unpasteurized milk.
Viruses cannot multiply in food but can survive long enough to infect people who consume contaminated food or water. Food handlers with poor hygiene are a major source of viral contamination.
Common foodborne viruses include:
- Norovirus – The leading cause of foodborne illness worldwide. It is the scourge of cruise ships, care homes and hospitals as it is highly contagious. It spreads through contaminated food, water, and surfaces, causing vomiting and diarrhea.
- Hepatitis A virus – Spread through contaminated food, water, or infected food handlers. It affects the liver and may cause fever, fatigue, jaundice, and abdominal discomfort.
Unlike bacteria, viruses require a living host to reproduce. Even small amounts of virus can cause illness.
Parasites are organisms that live on or inside another organism (the host) and obtain nutrients from it. Foodborne parasites are less common than bacteria and viruses but can cause severe illness.
Common foodborne parasites include:
- Trichinella spiralis – Found in undercooked pork and wild game.
- Toxoplasma gondii – Found in undercooked meat or contaminated produce.
- Giardia intestinalis – Often transmitted through contaminated water or improperly washed produce.
- Anisakis – Found in raw or undercooked marine fish and seafood. It can cause severe stomach pain and allergic reactions.
Parasites often have complex life cycles. As such the symptoms can be cyclical - and “go away” for a few weeks or months and then return.
The latest food born outbreak is from a parasite called Cyclospora cayetanensis , a microscopic parasite that causes prolonged gastrointestinal illness, particularly watery diarrhea (hence the term explosive), abdominal cramps, nausea, fatigue, loss of appetite and weight loss.
CURRENT OUTBREAK AND CHALLENGES
Cyclospora cayetanensis – has caused numerous outbreaks over the years linked to fresh produce such as lettuce, spinach, basil, cilantro, raspberries, and bagged salads. Cyclospora is normally transmitted when food or water becomes contaminated with human fecal material most often from irrigation water, or through poor sanitation during harvesting, processing and handling. It is not contagious between humans. Unlike many other foodborne pathogens, the parasite generally does not cause symptoms within hours or a few days after consumption. It takes time (1 to 3 weeks) to mature in the host. This makes it very challenging to track sources. Adding to the complexity of investigating outbreaks, testing for the parasite is also much more difficult than testing for bacteria and viruses. In fact, a negative food test does not necessarily prove that produce was uncontaminated, because only a small portion of a food shipment can usually be tested and contamination may be unevenly distributed. It is even challenging to determine what to test due to the delay in the onset of illness.
The 2026 Cyclospora outbreak in the United States has become one of the largest recorded outbreaks of cyclosporiasis. In July, federal investigators linked a major cluster of illnesses to shredded iceberg lettuce from central Mexico, served at Taco Bell restaurants in several states. Currently the FDA has confirmed over 10,000 cases with another 12,000 cases still being tested across 47 states in this specific lettuce-associated outbreak. The investigation has so far indicated that the lettuce supplied by Taylor Farms was the likely common source, and the company recalled affected iceberg lettuce products. However, research is continuing on other sources and raw products.
As of mid-July, Canadian officials reported no Canadian outbreak and no evidence that the implicated lettuce had been distributed in Canada, although Canadian authorities were monitoring the U.S. investigation.
Explosive Diarrhea - From Leafy Greens
BAGGED GREENS
It is just so convenient. Buy a salad kit, open it up, add the packaged dressing and the side dish is ready. For the most part, bagged greens should be safe, but they carry a higher risk of food poisoning than whole heads of lettuce. There have been numerous recalls due to outbreaks involving Listeria, E-Coli, Salmonella and cyclospora.
Because the greens are mixed, chopped, and packaged raw without a cooking step to kill germs, bacteria or parasites can spread quickly if contamination occurs in harvesting or processing. Wet plastic bags then create a cozy space for bacteria or parasites to multiply, especially if kept too warm. As well, large commercial washers combine massive quantities of greens together, meaning a single contaminated leaf can taint an entire production batch.
I would recommend NOT buying bagged salads or at least wash the greens well before using. There are food safe disinfection products that can also be used in washing raw produce. On a cautionary note about cyclospora, standard rinsing may reduce some microorganisms but does not reliably remove all parasite eggs or oocysts, making prevention at the farm and processing level especially important.
No one wants food poisoning and most of us have experienced it. My own motto – when in doubt DON’T. It is not worth the risk. That is why I avoid bagged salad, raw oysters, any uncooked food when travelling in several countries, some sushi items, steak tartar, raw sprouts (unless home grown) and sliced processed meats – especially if past the due date.
