U.S. health officials are investigating a growing outbreak of cyclosporiasis, a foodborne illness caused by the microscopic parasite Cyclospora cayetanensis, after hundreds of cases were reported across multiple states. The outbreak has prompted an investigation by the Centers for Disease Control and Prevention (CDC) and state health departments, although authorities have not yet identified a common source of contamination.
- The CDC is investigating a multi-state outbreak of cyclosporiasis caused by the Cyclospora parasite.
- More than 145 domestically acquired cases have been reported across 17 states, while Michigan is experiencing a separate, rapidly growing outbreak with hundreds of additional infections.
- The illness is typically linked to contaminated fresh produce or water rather than person-to-person transmission.
- Symptoms include severe watery diarrhea, stomach cramps, nausea, fatigue, and loss of appetite.
- Health officials have not identified a single food source connecting all reported cases.
The outbreak involves Cyclospora cayetanensis, a microscopic parasite that infects the small intestine and causes the illness known as cyclosporiasis. According to the CDC, 145 people in 17 states became ill after consuming contaminated food or water within the United States between May 1 and June 16. Twenty of those patients required hospitalization, although no deaths have been reported. Federal investigators, working alongside the U.S. Food and Drug Administration (FDA) and state health departments, are examining several clusters of infections to determine whether they share common sources. At present, officials say there is no evidence that all reported cases are linked to a single nationwide outbreak.
At the same time, Michigan has experienced a separate surge in infections that has far exceeded the state’s typical seasonal levels. Health authorities there have confirmed several hundred cases within a short period, prompting an intensive investigation into possible foodborne exposures. While officials continue to examine whether any links exist between the Michigan cases and outbreaks elsewhere, no definitive connection has been established.
Cyclospora infections most commonly occur after consuming food or water contaminated with human fecal matter. Fresh produce—including leafy greens, basil, cilantro, berries, and other fruits and vegetables that are eaten raw—has been associated with previous outbreaks because the parasite can survive on produce before reaching consumers. Since the parasite requires time to mature outside the human body before it becomes infectious, direct person-to-person transmission is considered highly unlikely.
Symptoms usually begin about one week after exposure but may appear anywhere from two days to two weeks later. The hallmark symptom is watery diarrhea, which can become frequent and severe. Patients may also experience abdominal cramping, bloating, nausea, vomiting, fatigue, low-grade fever, reduced appetite, and weight loss. Without treatment, symptoms may persist for several weeks or recur after temporarily improving.
Although many healthy individuals recover without long-term complications, the illness can be more serious for older adults, young children, pregnant women, and people with weakened immune systems. Severe diarrhea may lead to dehydration requiring hospitalization, particularly among vulnerable patients. The CDC reported that 20 people associated with the current outbreak have required hospital care.
Diagnosing cyclosporiasis can be challenging because routine stool tests do not always detect the parasite. Healthcare providers often need to order specialized laboratory testing when prolonged diarrhea raises suspicion of a parasitic infection. Once diagnosed, the illness is typically treated with the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX), which is considered the standard therapy. Alternative treatment options may be considered for patients who cannot take sulfonamide antibiotics.
The CDC advises consumers to reduce their risk by thoroughly washing fruits and vegetables, practicing good hand hygiene, and ensuring food preparation surfaces remain clean. However, officials note that rinsing produce alone may not completely eliminate the parasite, particularly if contamination occurred before harvest. Cooking food thoroughly remains one of the most effective ways to destroy the organism.
Cyclosporiasis is a seasonal illness in the United States, with cases typically increasing between May and August. Previous outbreaks have been linked to imported and domestically grown fresh produce, including basil, cilantro, raspberries, snow peas, and packaged salad mixes. Because the parasite has a relatively long incubation period, identifying contaminated food sources often requires extensive epidemiological investigations involving patient interviews and food supply tracing.
Federal and state health officials continue to investigate the current increase in cases while monitoring for additional infections. As more laboratory results become available and traceback investigations progress, authorities hope to determine whether specific food products or distribution chains are responsible for the recent illnesses. Until then, the CDC continues to encourage healthcare providers to report suspected cases promptly and advises consumers to seek medical attention if they develop persistent diarrhea or other symptoms consistent with cyclosporiasis.
Cyclospora is once again drawing national attention as the U.S. Centers for Disease Control and Prevention (CDC) investigates a multi-state outbreak of the foodborne parasitic illness. Health officials are working to identify the source of the Cyclospora infections while monitoring reported cases from several states. Public health agencies are encouraging consumers, healthcare providers, and food distributors to remain vigilant as the investigation continues.
CDC Launches Multi-State Cyclospora Investigation
The CDC has initiated a nationwide investigation after multiple Cyclospora infections were reported across several U.S. states. Epidemiologists are interviewing patients, tracing food sources, and analyzing laboratory data to determine whether the illnesses are linked to a common contaminated product.
Because Cyclospora outbreaks are often associated with fresh produce, investigators are carefully reviewing supply chains to identify potential sources of contamination
