There is an outbreak of cyclosporiasis happening. It’s a parasite that causes horrible diarrhea. Although we don’t know yet what the source is, there are ways to reduce your risk of getting infected.
Although most cases have been reported in Michigan, more than 30 states are affected, so it’s worth knowing the symptoms and how you can reduce your risk of getting it.
So what is this cyclo-thing?
Cyclosporiasis (yes, it’s a mouthful!) is a parasite that causes an infection in your gut. It spreads through food or water that is contaminated with human faeces (AKA poop). The good news is that this does not directly spread from person to person. You can’t get this if you are around someone who is infected, as the parasite needs to “sporulate”, which means the parasite needs time – days to weeks – in the environment to develop into a form that can infect people.
What are the main symptoms?
💩💥 The main symptom is watery and sometimes explosive diarrhea. When we talk about “explosive”, this means sudden onset, uncontrolled, and very watery.
🤢 Other symptoms include nausea, vomiting, stomach cramps and fatigue. Some folks also get a fever – these are all classic gastrointestinal symptoms (meaning they affect the stomach and gut).
🗓️ Symptoms usually show up within a week or so of exposure, but in some cases, it may be days, and in others weeks. And some folks never show any symptoms. Because of this delay in symptom onset, epidemiologists are having a hard time tracking down exactly what is causing this outbreak.
What do I do if I get it?
Although this is very unpleasant and can be severe in cases, the biggest risk is dehydration (loss of fluid) from the diarrhoea, so keeping your fluids up is really important. This is especially important for older folks, pregnant people, those who are immunocompromised, and kids, so make sure you contact a trusted clinician if you are worried.
If you have been diagnosed with cyclosporiasis (normally through a stool sample), your clinician might prescribe a course of antibiotics that kills the parasite.
💡If you’re getting tested, make sure to mention cyclosporiasis to your clinician specifically, as it’s not always included in standard stool testing.
Symptoms usually go away on their own after a few days, but it’s possible to experience diarrhoea on and off for a few weeks after. And especially if it’s been untreated, some people can experience relapses, meaning symptoms can come back, even months later.
It’s still not clear yet what the source of this outbreak is, but here are some general tips if you want to reduce the risk of getting an infection:
🥗 In the past, the main culprits have been fresh foods like bagged lettuce, leafy greens, fresh herbs like cilantro (also called coriander in some parts of the world) and berries, so one option is to avoid these types of products until we know more.
🔶 Cooking vegetables is the safest option as it kills the parasite. It needs to be 158F (or 70C), though. And if you use a microwave, temperatures need to be even higher.
Lettuce might be a bit meh if cooked, so if you want to eat lettuce, buy a head, peel off and throw away the outer layers, then wash each remaining leaf thoroughly. It won’t kill or remove all of the parasites if they’re present, but it’s a better option than bagged salad.
🔶 If you choose to eat raw fresh fruit or vegetables, make sure you wash them thoroughly (this might not get rid of all the parasites, but it can lower the count). And avoiding veggies and fruit with lots of wrinkles is also a good idea (the parasite loves to hide in nooks and crannies!)
🔶 Buy fresh fruit and vegetables you can peel – think cucumber, melon, bananas and the like. Make sure you still wash them, though.
🔶 If you can, buying local produce from a farmers’ market is also less risky, and even better if you grow your own.
🔶 Consider avoiding raw food when eating out, as you won’t necessarily know where the produce is from.
🫧 Thorough general hygiene routines around food preparation are always a good idea too. This includes washing your hands with soap and water before and after preparing raw veggies and fruit, and also cleaning work surfaces.
Something to be aware of:
The internet is rife with claims about “parasite cleansing” – an unproven “treatment” that usually consists of a combination of laxatives and herbal supplements. There is no evidence that they work, and in fact, they might make matters worse, especially if you are already dehydrated.
As always, we’ll keep watching this one for you.
Stay safe. Stay well.
Love,
Those Nerdy Girls
Useful resources:
Michigan Department of Health and Human Services (MDHHS) – Recommendations on preventing food-borne illness
Centers for Disease Control and Prevention(CDC) – Cyclosporiasis [archived link]
CDC – Surveillance of Cyclosporiasis [archived link]
CDC – Clinical Care of Cyclosporiasis [archived link]
NPR – What to know about the cyclosporiasis outbreak hitting more than half of U.S. states
Cleveland Clinic – No, you don’t need a “parasite cleanse”
And if you want to nerd out and dive a little deeper, check out this brief by The Evidence Collective with tons of information
Link to Original Substack Post
(information correct as of 7/12/26)
