Explosive Diarrhoea Outbreak Hits US: 1,400+ Cases as Parasite Source Remains a Mystery

A rare parasite causing explosive diarrhoea has infected more than 1,400 people across the United States, with Michigan alone recording over 1,000 cases in a two-week period. Health officials are scrambling to identify the source as the outbreak spreads across at least 18 states, with Ohio reporting more than 500 cases and New York City logging 273 infections since May.

Health officials across the United States are racing to contain an outbreak of a rare parasite that causes explosive diarrhoea, with cases soaring past 1,400 in recent weeks.

The illness, known as cyclosporiasis, is caused by the microscopic parasite Cyclospora cayetanensis, which spreads through contaminated food or water. The main symptom is watery, frequent and sometimes explosive diarrhoea that can last for days or even weeks.

The outbreak has hit Michigan hardest, with the state recording more than 1,000 cases in just two weeks a dramatic surge compared to the typical 50 cases seen in an entire year. Neighbouring Ohio has reported more than 500 cases, while New York City has logged 273 infections since May 1. Cases have also been confirmed in Illinois, Texas, Florida, Pennsylvania and at least 10 other states.

No deaths have been reported, but at least 36 people have been hospitalized, with health officials warning that young children and older adults are most susceptible to severe illness.

What is cyclosporiasis?

Cyclosporiasis is a foodborne illness caused by a microscopic parasite that infects the small intestine. The parasite is typically transmitted through contaminated fresh produce including basil, cilantro, lettuce, raspberries, snow peas and green onions and is not spread directly from person to person.

The illness is not usually life-threatening, but symptoms can be severe and persistent. Without antibiotics, the disease can last from a few days to more than a month, and symptoms may return after appearing to subside.

Where has the outbreak spread?

According to the CDC and state health departments, cases have been confirmed in at least 18 states:

• Michigan – 1,000+ cases (two-week period)
• Ohio – 500+ cases
• New York City – 273 cases
• Illinois – 141+ cases
• Florida – 1-10 cases
• Texas, Georgia, Pennsylvania, Wisconsin, North Carolina, Tennessee, Virginia, Louisiana, Massachusetts, Colorado, Connecticut, New Jersey, Alaska – confirmed cases

Health officials are still searching for the source

Despite the rapid spread, authorities have not yet identified a specific food source. Past outbreaks in the US have been linked to contaminated produce, and the CDC is working with the FDA to trace the origin.

Health officials believe the true number of cases is significantly higher than reported, as many people recover without seeking medical care or being tested. The outbreak also comes after the Trump administration dramatically scaled back federal food surveillance programs last year, which previously required checks for Cyclospora.

What are the symptoms?

The main symptom is frequent, watery and sometimes explosive diarrhoea, accompanied by:

• Stomach cramps and nausea
• Vomiting and fever
• Loss of appetite and weight loss
• Fatigue

Symptoms typically appear about one week after infection and may persist for up to a month if untreated.

How can you protect yourself?

Health authorities recommend:

• Washing all fruits and vegetables thoroughly under running water before eating
• Scrubbing firm produce like melons and cucumbers with a clean brush
• Cooking produce when possible to kill parasites
• Avoiding raw leafy greens and fresh herbs until the source is identified

People who experience diarrhoea lasting more than 48 hours are urged to contact a healthcare provider and ask about testing for Cyclospora. The infection is treatable with specific antibiotics.

FAQ:

Q: What is causing the explosive diarrhoea outbreak in the US?
A: The outbreak is caused by Cyclospora cayetanensis, a microscopic parasite that spreads through contaminated food or water. It causes an illness called cyclosporiasis, which leads to frequent, watery and sometimes explosive diarrhoea.

Q: How many cases of explosive diarrhoea have been reported in the US?
A: More than 1,400 cases have been reported across at least 18 states. Michigan alone has recorded over 1,000 cases in two weeks far above the typical 50 cases seen in a full year.

Q: How does cyclospora spread and can it be passed from person to person?
A: The parasite is transmitted through contaminated food or water, not directly from person to person. Past outbreaks have been linked to contaminated produce including basil, cilantro, lettuce and raspberries.

Q: What should I do if I have symptoms of explosive diarrhoea from this outbreak?
A: If you experience diarrhoea lasting more than 48 hours, contact a healthcare provider and ask to be tested for cyclospora. The infection is treatable with antibiotics.

Q: Why are federal officials struggling to find the source of the cyclospora outbreak?
A: The source has not yet been identified because contamination typically occurs at the farm or irrigation level, making traceback investigations difficult. In addition, federal food surveillance programs were scaled back last year, reducing testing for cyclospora.