what is the new diarrhea virus and how can you protect yourself?

A Diarrhea Outbreak, Not a New Virus

The 2026 U.S. outbreak described by health authorities is cyclosporiasis, an intestinal infection caused by the parasite Cyclospora cayetanensis, not a newly identified virus. Johns Hopkins Medicine reported cases in more than 30 states in its July 17, 2026 update, while public health agencies investigated and the source remained unknown (Johns Hopkins Medicine’s outbreak update).

The label “new diarrhea virus” does not identify a specific diagnosis. Viral gastroenteritis, sometimes called a stomach bug, can be caused by viruses such as norovirus and rotavirus, but cyclosporiasis is a separate, parasitic illness. Symptoms can overlap, so diarrhea alone cannot reveal its cause.

Cyclospora usually spreads when someone eats contaminated food or drinks contaminated water. Washing produce and using safe drinking water may reduce exposure, though washing cannot guarantee that produce is free of the parasite. If diarrhea persists or you are concerned about possible exposure, contact a health care provider to discuss testing and appropriate care.

How Cyclospora Spreads

Cyclosporiasis is a food- or waterborne intestinal infection caused by Cyclospora cayetanensis, a parasite. People become infected by swallowing the parasite, usually in contaminated produce or water. Produce may be exposed to contaminated water carrying human feces, or contaminated during food handling when hygiene is poor. Johns Hopkins Medicine describes how Cyclospora spreads.

This route differs from infections that commonly pass between people through close contact. Johns Hopkins says cyclosporiasis is not spread person to person, while UC Davis describes direct transmission as very rare. The parasite’s presence in food or water, rather than simply being near someone who is ill, is the relevant exposure.

A small amount of contamination can be enough: Johns Hopkins notes that only a few infectious oocysts, the parasite’s infectious form, may cause illness. That does not mean every serving of produce is contaminated, and ordinary appearance cannot establish whether food carries the parasite.

The source of the 2026 outbreak had not been identified in the cited Johns Hopkins update. Earlier outbreaks have been associated with salad greens, herbs such as basil and cilantro, raspberries, and peas. Follow public health notices for any confirmed food warnings rather than treating past associations as evidence about a particular product.

Understanding the exposure route can help distinguish a foodborne illness concern from everyday person-to-person contact. Individual medical advice should still come from a clinician, particularly if symptoms develop or persist.

Symptoms and Timing

Watery diarrhea is the main symptom of cyclosporiasis. It may be frequent and, at times, severe. Nausea, reduced appetite, abdominal cramps, bloating, gas, fatigue, and weight loss can also occur. Vomiting or fever is possible, but is not typically prominent with Cyclospora infection, according to UC Davis Health.

Symptoms usually begin about a week after exposure, though they may appear sooner or later. Without treatment, diarrhea can continue for weeks or months, and symptoms may ease before returning. The illness and its timing are described in Johns Hopkins Medicine’s cyclosporiasis guidance.

Symptoms alone cannot confirm Cyclospora. Other infections, including viral gastroenteritis, can cause diarrhea and related digestive problems, so a clinician may need stool testing to identify the cause.

Norovirus is one possible cause of viral gastroenteritis. Unlike cyclosporiasis, it can spread through contaminated food or surfaces and direct contact with an infected person, and symptoms commonly last a shorter time. A Mayo Clinic overview of viral gastroenteritis explains its symptoms and spread.

Prevention Through Food and Water Safety

Food and water safety can lower the chance of exposure to Cyclospora cayetanensis, but washing produce cannot guarantee that it is free of contamination. Rinse fruits and vegetables under clean running water before eating or preparing them, and scrub firm produce with a clean brush. Cooking produce when appropriate may kill or reduce the parasite, according to Johns Hopkins Medicine.

Washing is still worthwhile, even though it may not remove all contamination. When practical, choose whole, less-processed produce, such as a head of lettuce instead of bagged greens. These steps can reduce exposure, but none can guarantee safety.

Wash your hands with soap and water after using the toilet or changing diapers, and before preparing food or eating. Cyclospora spreads through food or water contaminated with human feces. Do not drink untreated water from lakes, streams, springs, or other uncertain sources. The New York State Department of Health’s Cyclospora guidance also recommends rinsing fresh produce and practicing careful hand hygiene.

Past outbreaks have been associated with particular fresh and processed produce, including salad greens, herbs, berries, and peas. Those historical links do not mean all produce is unsafe. During an active investigation, check current public health notices and follow product-specific recall instructions, including directions to discard or return recalled items.

When seeking medical advice about foodborne illness, ask a clinician about symptoms or risks rather than relying on broad assumptions about particular foods.

Testing, Treatment, and When to Get Help

Persistent diarrhea or suspected exposure to Cyclospora is a reason to contact a physician or clinic and ask whether testing is appropriate. Symptoms overlap with many other illnesses, so guessing at the cause can delay the right care.

Cyclosporiasis is diagnosed by examining a stool sample for the parasite. Testing can help identify this treatable infection among the many possible causes of diarrhea, as Johns Hopkins Medicine explains.

When testing confirms cyclosporiasis, treatment is the antibiotic trimethoprim/sulfamethoxazole, taken under a clinician’s direction. Some infections may improve without medication, but Johns Hopkins recommends treatment for confirmed cases. Do not self-diagnose or start leftover antibiotics: the cause of diarrhea matters, and some infections can be harmed by inappropriate antibiotic use.

Replacing fluids is an important part of care during diarrheal illness. A clinician can advise on hydration and whether additional treatment, such as antidiarrheal medication, is appropriate for the individual situation.

When should you seek urgent care?

Severe diarrhea accompanied by dizziness when standing or a rapidly increasing heart rate warrants prompt evaluation at an urgent care center or hospital, according to the Johns Hopkins guidance on cyclosporiasis. These symptoms can signal significant fluid loss and should not be managed by waiting for symptoms to pass.

People who are immunocompromised may face a greater risk of severe illness from diarrheal infections. If they suspect cyclosporiasis, they should contact their physician or care clinic promptly for assessment and advice about testing and treatment.

Stay Informed and Seek Individual Advice

The reported 2026 outbreak concerns cyclosporiasis, an intestinal infection caused by the parasite Cyclospora cayetanensis, not a newly discovered diarrhea virus. In its July 17, 2026 update, Johns Hopkins Medicine said the source was still under investigation.

For readers in New York City, the practical steps are familiar: handle produce safely, choose safe drinking water, and wash hands before preparing or eating food. Past outbreaks have involved several types of produce, but that does not mean a product is under recall.

Check current notices from public health agencies for outbreak updates and product-specific warnings, and follow any recall instructions. Do not rely on older food lists as a guide to what is safe now.

If diarrhea persists or you suspect exposure, contact a healthcare professional to discuss whether stool testing is appropriate and what treatment may be needed. Individual advice matters because similar symptoms can have different causes, and a clinician can help determine the right next step.