Cyclosporiasis Symptoms in Older Adults: What to Know

On July 9, 2026, the CDC confirmed 843 domestically acquired cases of cyclosporiasis spread across 31 states — with more than 1,500 additional cases still under analysis. That number almost certainly understates the real picture, since many people recover without ever being tested. But the trajectory is hard to ignore: multiple states logged a steeper jump in cases over the last two weeks than during the same period in 2025. The following day, AARP updated a dedicated advisory specifically flagging that cyclosporiasis symptoms in older adults can spiral into serious complications that younger, healthier people often dodge. If you've had diarrhea dragging on for more than a few days, this is worth reading carefully.

What Is Cyclosporiasis and Why Is It Spreading Now?

Cyclosporiasis is caused by Cyclospora cayetanensis, a microscopic parasite that lives in contaminated water and produce. You can't see it, smell it, or taste it. It enters the body when you swallow oocysts — the parasite's hardy, infectious form — typically from fresh herbs, leafy greens, or berries that haven't been cooked. Spring and summer are peak seasons, partly because warmer weather extends the window for produce contamination and partly because fresh-herb-heavy dishes spike in popularity.

The foods most often implicated in past outbreaks read like a farmers' market list: basil, cilantro, spinach, mixed lettuce blends, raspberries, and strawberries. That's not a reason to abandon salads forever — but it is a reason to pay closer attention right now, while this outbreak is active.

Cooking kills the parasite. Produce heated to 158°F or higher is safe. Raw or lightly rinsed is where the risk lives.

Cyclosporiasis Symptoms Older Adults Need to Recognize

The classic presentation is watery diarrhea — sometimes explosive, often crampy — paired with nausea, fatigue, loss of appetite, and bloating. Some people run a low-grade fever. What sets this illness apart from a standard stomach bug is how long it lingers. Without treatment, symptoms can stretch on for weeks, disappear briefly, and then come roaring back. That relapsing pattern is a hallmark of Cyclospora infection and one reason it's so easy to dismiss as "something I ate" until it keeps returning.

For most healthy adults, cyclosporiasis is miserable but not life-threatening. For older adults, the math shifts. AARP's updated advisory warns that older adults face elevated risk of dehydration, electrolyte imbalance, acute kidney injury, falls, and worsening of existing chronic conditions — all of which can cascade quickly when diarrhea is severe and persistent. If you're managing heart disease, diabetes, kidney issues, or take medications that affect hydration or blood pressure, prolonged diarrhea isn't something to wait out on your own.

The CDC's current data includes 86 hospitalizations among the 843 confirmed cases — a hospitalization rate that reflects just how serious this can get for vulnerable populations.

The Testing Problem Nobody Warns You About

Here's the part that genuinely matters and often gets buried: routine stool tests don't detect Cyclospora. Standard stool cultures and typical gastrointestinal panels are designed to catch common bacterial culprits like Salmonella or E. coli. Cyclospora cayetanensis requires a specialized test — either modified acid-fast staining or PCR testing — that a clinician must explicitly request.

As Pharmacy Times reports, clinicians must specifically order cyclospora testing, and it's routinely left off standard diarrhea workups. That means you could see a doctor, have a stool test run, get a clean result, and still have an active Cyclospora infection — simply because no one thought to look for it.

The practical takeaway: if you have diarrhea that isn't clearing up after several days, especially if it's watery, crampy, and coming in waves, ask your doctor directly — "Could this be Cyclospora? Do I need a specific test for it?" Don't assume that a normal test result rules it out. It doesn't, unless cyclospora testing was specifically included.

What the Evidence Says About Treatment

The good news is that cyclosporiasis responds well to antibiotics once it's diagnosed. The standard treatment is trimethoprim-sulfamethoxazole (TMP-SMX), sold under brand names like Bactrim or Septra. Most people improve noticeably within a few days of starting treatment, though the full course matters — stopping early risks relapse.

People with sulfa allergies face a trickier road, since TMP-SMX isn't an option for them and alternative treatments have less evidence behind them. If that's your situation, flag it immediately with your provider so they can plan accordingly.

While you're waiting for diagnosis or recovery, hydration is the most important thing you can do at home. Frequent diarrhea depletes fluids and electrolytes faster than most people realize, and older adults feel the effects more acutely. Water is good; oral rehydration solutions (like Pedialyte or similar) are better because they replace electrolytes, not just fluids. Avoid alcohol and caffeine, which accelerate dehydration.

Video: Cyclospora Parasite Outbreak: Symptoms, Treatment and How It Spreads -- UC Davis Health

What You Can Do Right Now About Your Food

During an active outbreak, a few habits are worth revisiting. Rinsing produce is always a good practice, but it won't eliminate Cyclospora — the oocysts are small enough and sticky enough to survive a standard rinse. What actually works is heat.

If you're using fresh basil, cilantro, spinach, or berries and you can cook them into a dish rather than eating them raw, that's the safest choice right now. Pesto, sautéed greens, cooked berry compote — heat the produce to at least 158°F and the parasite is dead. For salads and raw herbs where cooking isn't realistic, buying from reliable sources and being aware of your body in the days that follow is the best you can do.

Wash your hands thoroughly before preparing food, and be especially careful if anyone in your household is immunocompromised, pregnant, or elderly. The parasite doesn't spread person-to-person the way norovirus does — it needs time to become infectious after leaving the body — but kitchen hygiene still matters.

When to Make the Call and Who Should Know

See a healthcare provider promptly if you have diarrhea lasting more than three days, if you notice blood in your stool, if you're having trouble keeping fluids down, or if you feel dizzy or lightheaded — signs of significant dehydration. Don't wait to see if it passes on its own, particularly if you're over 65 or managing chronic health conditions.

It's also worth making sure someone close to you knows when you're not feeling well. SteadiDay's free Trusted Contacts feature lets you designate people — a family member, neighbor, or close friend — who can check in on you when something seems off. You don't have to be in crisis for it to be useful. A few days of miserable diarrhea and reduced appetite is exactly the kind of situation where having someone looped in matters, especially if you live alone.

If you do visit a clinic or urgent care, bring a list of your current medications. Some drugs interact with TMP-SMX, the antibiotic used to treat cyclosporiasis, and your provider will need that information to prescribe safely.

Common Questions

How do I know if my diarrhea could be cyclosporiasis and not just a stomach bug?

The biggest clue is duration and pattern. A typical stomach bug resolves in one to three days. Cyclosporiasis tends to linger for weeks without treatment and may seem to improve before coming back. Watery, crampy diarrhea that keeps returning — especially after eating fresh produce in spring or summer — is worth discussing with a doctor, who can order a specific stool test for Cyclospora.

Will a standard stool test show if I have Cyclospora?

Usually not. Routine stool cultures and standard gastrointestinal panels don't detect Cyclospora cayetanensis. You need a specialized test — modified acid-fast staining or PCR — that must be explicitly requested by your clinician. If cyclospora is a concern, ask your provider specifically to include that test.

Are older adults more likely to get cyclosporiasis, or just more likely to get sicker from it?

Anyone can contract cyclosporiasis by eating contaminated produce or water. Older adults aren't more likely to be exposed, but they face a higher risk of serious complications — including dehydration, electrolyte imbalance, acute kidney injury, and falls — if the infection goes untreated. Those managing chronic conditions or taking multiple medications may experience worsened symptoms more quickly.

Is there anything I can do to make fresh produce safer during this outbreak?

Cooking produce to at least 158°F kills Cyclospora, so heating herbs, greens, and berries when possible is the most reliable protection. Standard rinsing does not eliminate the parasite. During an active outbreak, it's reasonable to limit raw consumption of the produce most often linked to past outbreaks — basil, cilantro, spinach, lettuce blends, and berries — or opt for cooked preparations when you can.