Parasite outbreak explosive diarrhea: CDC investigates growing Cyclospora cases across the U.S.
CDC investigates growing Cyclospora parasite outbreak linked to severe explosive diarrhea
A growing Cyclospora outbreak has prompted health officials across the United States to intensify investigations after more than 400 people in at least 18 states were infected with a foodborne parasite that causes severe gastrointestinal illness. Public health experts say the surge in cases is unusually high for this time of year, with at least 20 hospitalizations reported, although no deaths have been confirmed.
The parasite, Cyclospora cayetanensis, causes an intestinal infection known as cyclosporaiasis, which is commonly associated with contaminated fresh produce or water. While outbreaks typically occur during the spring and summer months, officials say this year’s increase is notable because investigators have not yet identified a common source.
The Centers for Disease Control and Prevention (CDC), along with the Food and Drug Administration (FDA) and state health departments, are actively investigating multiple clusters of infections.
Cyclospora Outbreak Expands Across Multiple States
Health authorities say confirmed cases continue to rise across the country.
According to the CDC, at least 145 domestically acquired cases had already been identified across 17 states during the initial reporting period ending in mid-June. Since then, additional state reports have pushed the national total beyond 400 confirmed infections.
Michigan has emerged as one of the hardest-hit states, reporting more than 300 cases alone, far above its annual average of approximately 50 infections. Other states reporting elevated case numbers include New York, Texas, Illinois, and Michigan, with New York City recording roughly twice as many infections as during the same period last year.
Public health experts caution that official numbers likely underestimate the true scale of the outbreak because many people experiencing diarrhea do not seek medical care or undergo laboratory testing.
What Is Cyclospora and How Does It Spread?
Cyclospora is a microscopic parasite transmitted primarily through food or water contaminated with human feces.
Unlike many gastrointestinal illnesses, the parasite does not usually spread directly from person to person. After leaving an infected person’s body, Cyclospora requires several days or even weeks in the environment before it becomes capable of infecting another individual.
Historically, outbreaks have been linked to imported fresh produce including:
- Basil
- Cilantro
- Raspberries
- Spinach
- Romaine lettuce
- Snow peas
- Mixed salad greens
Although investigators suspect contaminated produce may again be responsible, officials have not identified a specific food item linked to the current outbreak.
Explosive Watery Diarrhea Among Most Common Symptoms
Medical experts say the hallmark symptom of cyclospora infection is explosive watery diarrhea, often accompanied by persistent stomach discomfort.
Other symptoms include:
- Severe abdominal cramps
- Nausea
- Vomiting
- Fatigue
- Loss of appetite
- Bloating
- Low-grade fever
- Muscle aches
Symptoms generally develop about one week after exposure, although they may appear anywhere between two days and two weeks later.
Doctors warn that dehydration can become a serious concern, particularly for:
- Young children
- Older adults
- Pregnant women
- Individuals receiving cancer treatment
- Organ transplant recipients
- People with weakened immune systems
Most healthy individuals recover fully, but some patients require hospitalization due to severe dehydration.
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Health Officials Continue Search for the Source
Investigators from the CDC, FDA, and state health agencies are working together to determine whether the cases share a common source.
Tracing outbreaks of Cyclospora is particularly challenging because symptoms often appear several days after eating contaminated food. By the time patients become ill, many struggle to accurately remember what they consumed.
Experts say previous outbreaks have eventually been linked to nationally distributed produce, but no evidence currently suggests that all of this year’s cases originated from a single contaminated product.
Officials continue interviewing patients and analyzing food distribution records in an effort to pinpoint the source.
Treatment and Prevention Advice
Cyclospora infection is treatable with the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX), commonly prescribed under brand names including Bactrim, Septra, and Cotrim.
Doctors advise anyone experiencing persistent watery diarrhea, particularly in areas reporting outbreaks, to seek medical evaluation rather than assuming symptoms will resolve on their own.
Health officials recommend reducing the risk of infection by:
- Washing hands thoroughly before preparing food.
- Rinsing fresh fruits and vegetables under running water.
- Scrubbing firm produce with a clean produce brush.
- Cutting away bruised or damaged portions.
- Refrigerating pre-cut fruits and vegetables promptly.
- Drinking plenty of fluids if vomiting or diarrhea develops.
While washing produce helps reduce contamination, experts note that it may not completely eliminate microscopic parasites.
Public Health Agencies Urge Vigilance
As investigations continue, health officials are encouraging consumers to remain alert but not panic.
Experts emphasise that Cyclospora infections are treatable when diagnosed promptly, and they encourage anyone with persistent gastrointestinal symptoms, especially severe watery diarrhea, to contact a healthcare provider.
Until investigators identify the contaminated source, consumers are advised to practise safe food handling and remain informed through updates from local and federal public health agencies.
FAQ
What is Cyclospora?
Cyclospora is a microscopic parasite called Cyclospora cayetanensis that causes an intestinal illness known as cyclosporiasis. It is usually spread through contaminated food or water.
What are the symptoms of Cyclospora infection?
Common symptoms include explosive watery diarrhea, stomach cramps, nausea, vomiting, bloating, fatigue, loss of appetite, low-grade fever, and muscle aches. Symptoms usually appear about one week after infection.
Why are Cyclospora cases increasing in 2026?
Health officials say there are unusually high numbers of infections across multiple states. Investigators are still trying to determine whether contaminated produce or another food source is responsible.
Which states have reported Cyclospora cases?
Michigan has reported the highest number of cases, while New York, Texas, Illinois, and several other states have also confirmed infections. Cases have been reported across at least 18 states.
How do people become infected with Cyclospora?
People usually become infected after consuming food or water contaminated with human feces carrying the parasite. Fresh produce is the most common source during outbreaks.
Is Cyclospora contagious from person to person?
No. Cyclospora is generally not spread directly between people because the parasite must mature in the environment before becoming infectious.
What foods have been linked to Cyclospora outbreaks?
Past outbreaks have been associated with basil, cilantro, spinach, raspberries, romaine lettuce, mixed salad greens, and snow peas. Officials have not yet identified the food responsible for the current outbreak.
How is Cyclospora treated?
Doctors typically prescribe the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX), which is highly effective in treating the infection.
Can Cyclospora cause hospitalization?
Yes. Severe dehydration caused by prolonged diarrhea may require hospitalization, especially among young children, older adults, and people with weakened immune systems.
How can I prevent Cyclospora infection?
Wash your hands regularly, rinse fruits and vegetables thoroughly, refrigerate fresh produce properly, and seek medical care if you develop persistent watery diarrhea.
How long does Cyclospora illness last?
Without treatment, symptoms may last for several weeks or recur. Most patients recover more quickly after receiving appropriate antibiotics.
Has the CDC identified the source of the outbreak?
No. As of the latest update, the CDC, FDA, and state health departments are still investigating the source of the current Cyclospora outbreak.