A mysterious parasite outbreak is spreading across the United States, leaving health officials scrambling to identify its source as more than 140 people have already fallen ill with a severe intestinal infection that can cause explosive diarrhea, intense stomach pain, vomiting, and prolonged exhaustion.

The Centers for Disease Control and Prevention (CDC) confirmed that at least 145 people from 20 states contracted the parasite Cyclospora cayetanensis between May and mid-June, with 20 patients requiring hospitalization. Fortunately, no deaths have been reported so far, but investigators fear the true number of infections may be significantly higher.

What makes the outbreak especially concerning is that none of the infected individuals recently traveled outside the United States—a major clue that has shifted investigators’ attention toward the nation’s food supply.

Cyclospora infections are typically associated with international travel, particularly to tropical and subtropical regions where contaminated food or water can expose people to the microscopic parasite. Historically, Americans contracted the illness while vacationing abroad or after consuming imported food products.

This time, however, the pattern looks very different.

Health officials say every indication points toward food consumed inside the United States.

Exactly which food remains unknown.

Local, state, and federal investigators—including the CDC and the Food and Drug Administration (FDA)—are now working together to trace multiple clusters of infections reported across the country. Despite weeks of investigation, authorities have not yet identified the common source linking the patients.

The uncertainty has only heightened concerns.

Because symptoms often do not appear until about a week after exposure, experts warn additional cases may continue emerging even as investigators search for answers.

The illness, known as cyclosporiasis, primarily attacks the digestive system.

Patients frequently experience sudden, watery diarrhea that can become severe enough to cause dehydration. Many also report painful abdominal cramping, nausea, vomiting, fatigue, bloating, loss of appetite, and low-grade fever. While some individuals recover without treatment, symptoms can linger for a month or even longer if left untreated.

Doctors generally prescribe the antibiotic trimethoprim-sulfamethoxazole—commonly sold under brand names such as Bactrim or Septra—to eliminate the parasite.

Medical experts stress that early diagnosis is important because untreated infections can leave patients weak and dangerously dehydrated.

The outbreak spans an unusually broad geographic area.

New York currently has the highest number of reported infections, with between 31 and 80 confirmed cases. Texas and Illinois have reported the next-highest totals, while additional infections have been confirmed in New Jersey, Connecticut, Pennsylvania, Massachusetts, Rhode Island, Delaware, Maryland, Virginia, North Carolina, Ohio, Tennessee, Wisconsin, Georgia, Florida, Louisiana, Colorado, Alaska, and Washington, D.C.

Investigators believe the actual number of infections is likely much higher because many patients experiencing diarrhea may never seek medical care or undergo specialized testing required to identify Cyclospora.

That possibility makes identifying the contaminated food source even more urgent.

Cyclospora spreads when microscopic parasite particles contaminate food or water through human fecal matter. Unlike many common stomach viruses, the parasite does not typically spread directly from one person to another, making contaminated food the leading suspect.

Fresh produce has repeatedly been linked to previous Cyclospora outbreaks.

Over the past decade, cilantro, basil, raspberries, sweet peas, mesclun lettuce, and other fresh vegetables have all been associated with infections. In 2019, imported basil from Mexico was linked to another multistate outbreak, while nearly 400 people became sick during a 2018 outbreak traced to contaminated McDonald’s salads.

At this stage, investigators have not connected the current outbreak to any specific fruit, vegetable, restaurant, or distributor.

Until they do, public health officials are encouraging consumers to carefully wash fresh produce, follow proper food-handling guidelines, and remain alert for symptoms—especially persistent diarrhea lasting several days.

Anyone experiencing severe gastrointestinal symptoms, particularly after eating fresh produce, is encouraged to seek medical attention.

Officials emphasize that while the investigation continues, there is currently no recommendation for consumers to avoid any specific food products.

Still, the unanswered questions surrounding the outbreak continue to fuel concern.

With infections stretching across 20 states, hospitalizations rising, and investigators still unable to identify the contaminated source, health authorities face a race against time to stop additional Americans from becoming the next victims of this mysterious parasite.