Michigan’s Cyclosporiasis Outbreak: Updates

Michigan’s cyclosporiasis outbreak has continued to draw public attention after thousands of reported infections, hundreds of hospitalizations, and two reported deaths. While the vast majority of people recover, the outbreak is an important reminder that persistent gastrointestinal illness should not always be dismissed as a routine “stomach bug.”

Cyclosporiasis is usually treatable. The danger comes when prolonged diarrhea leads to dehydration, electrolyte abnormalities, kidney stress, or worsening of underlying medical conditions—especially in older adults, young children, pregnant individuals, immunocompromised patients, and people with significant chronic disease.

Watch Dr. Anthony Oraha discuss the Michigan cyclosporiasis outbreak, symptoms, treatment, and prevention in this recent news segment: Watch the interview on YouTube

As of August 6, 2026, Reuters reported that Michigan had 12,485 cyclosporiasis cases, 279 hospitalizations, and two deaths associated with the outbreak. Health officials reported that new cases were slowing, and Michigan eased prior lettuce guidance while continuing to advise caution around recalled products and safe food handling.

What Is Cyclosporiasis?

Cyclosporiasis is an intestinal infection caused by Cyclospora cayetanensis, a microscopic parasite. It most commonly spreads when people eat food or drink water contaminated with the parasite.

The illness can cause:

• Frequent watery diarrhea
• Stomach cramps
• Bloating
• Nausea
• Loss of appetite
• Fatigue
• Weight loss
• Low-grade fever

Symptoms often begin about one week after exposure, though the timing can vary. One reason this infection can be missed is that it does not always behave like a short-lived viral stomach illness. If untreated, symptoms may last days to weeks, and they can sometimes improve and then return.

Why the Two Deaths Matter

Death from cyclosporiasis is uncommon in the United States. In Michigan’s outbreak, the two reported deaths occurred in individuals with significant underlying health conditions that may have been worsened by the infection and dehydration.

That distinction matters.

In most otherwise healthy people, Cyclospora causes a treatable diarrheal illness. But in medically vulnerable patients, prolonged diarrhea can become physiologically dangerous. Fluid loss can lead to dehydration. Dehydration can stress the kidneys, alter electrolytes, worsen weakness, and destabilize chronic medical conditions.

A useful way to explain this is: the parasite may trigger the illness, but the downstream effects—dehydration, electrolyte imbalance, kidney stress, and loss of physiologic reserve—are often what make diarrheal infections dangerous in high-risk individuals.

How Is It Spreading?

Michigan health officials have focused their investigation on foodborne exposure, particularly fresh produce. Earlier MDHHS updates indicated that lettuce or salad greens were a possible source, although officials emphasized that no single produce type, grower, or supplier had been identified at that time. MDHHS also noted that recreational water exposure, such as swimming in lakes, was not a recognized risk factor for cyclosporiasis and was not linked to the outbreak.

Cyclospora is not typically spread directly from person to person. The parasite usually needs time outside the body to become infectious, which makes direct household spread less likely than foodborne exposure.

Why Washing Produce May Not Be Enough

Washing produce is still important, but Cyclospora is more difficult to remove than many people realize.

The FDA notes that Cyclospora can be resistant to standard chlorine-based sanitizers, that commercial washing may not be sufficient, and that consumers should not use soap or bleach to wash produce. Rinsing under clean running water remains an appropriate first step, but washing alone may not reliably eliminate the parasite.

That means “pre-washed” does not guarantee Cyclospora-free.

For lettuce and leafy greens, MDHHS previously recommended purchasing whole heads of lettuce rather than pre-washed bagged lettuce or salad kits, discarding the outer two to three leaves, and washing the remaining inner leaves under clean running water.

How Cooking Helps Prevent Cyclospora

The most reliable way to kill Cyclospora is heat.

MDHHS and the FDA state that cooking food to at least 158°F / 70°C kills Cyclospora. This is especially relevant for produce that can reasonably be cooked, such as leafy greens, herbs, green onions, and other vegetables.
Practical options include:

• Sautéing greens
• Steaming vegetables
• Adding greens to soups
• Stir-frying vegetables
• Cooking herbs into sauces
• Baking or cooking produce when appropriate

This does not mean people must stop eating fruits and vegetables. It means that during an active outbreak, especially for higher-risk individuals, cooked produce is a safer option than raw produce when cooking is practical.

When to Call a Healthcare Provider

People should contact a healthcare provider if they develop sudden, persistent watery diarrhea—especially if symptoms last more than a few days, are severe, or occur during a known local outbreak.

A key point: routine stool testing may miss Cyclospora. CDC guidance states that testing for Cyclospora is not routinely conducted in most U.S. laboratories, and not all gastrointestinal PCR panels include it. If Cyclospora is suspected, healthcare providers should specifically request testing for it.

Patients may also need more than one stool specimen because the parasite may not be shed consistently enough to show up on a single test.

When to Seek Urgent or Emergency Care

The major immediate risk from cyclosporiasis is dehydration. Medical care should not be delayed if symptoms suggest significant fluid loss or physiologic stress.

Seek urgent or emergency care for:

• Very little urination
• Dizziness or fainting
• Confusion
• Severe weakness
• Inability to keep fluids down
• Severe abdominal pain
• Blood or black stool
• High fever
• Diarrhea in an older adult, infant, pregnant person, immunocompromised patient, or someone with significant chronic disease

In these situations, the question is no longer simply whether someone has Cyclospora. The concern is whether the body is becoming dehydrated or unstable.

How Cyclosporiasis Is Treated

The standard treatment for cyclosporiasis is an antibiotic called trimethoprim-sulfamethoxazole, often known as TMP-SMX, Bactrim, Septra, or Cotrim. The CDC identifies TMP-SMX as the treatment of choice, with a typical adult regimen of one double-strength tablet twice daily for seven to ten days.

Treatment must be individualized. People with sulfa allergy, pregnancy considerations, kidney disease, medication interactions, or immune compromise should discuss options with their healthcare provider. The CDC notes that no highly effective alternative has been identified for patients who cannot take TMP-SMX.

Hydration is also essential. For many patients, oral rehydration with fluids that contain both salt and sugar is more useful than plain water alone, especially when diarrhea is frequent.

The Bottom Line

Cyclosporiasis is usually treatable, but it should be taken seriously—particularly during a large outbreak.

The two reported deaths in Michigan are a reminder that prolonged diarrhea is not benign. For medically vulnerable individuals, the danger often comes from dehydration, electrolyte changes, kidney stress, and worsening of underlying conditions.

The practical takeaways are clear:

• Do not ignore persistent watery diarrhea.
• Ask specifically about Cyclospora testing.
• Prioritize hydration.
• Seek urgent care for signs of dehydration or severe illness.
• Cook produce when possible, especially during an outbreak.
• Remember that washing helps, but heat is the most reliable way to kill the parasite.

If you or a loved one has persistent diarrhea, worsening weakness, dizziness, confusion, or difficulty staying hydrated, contact a healthcare professional promptly.