Cyclosporiasis Outbreak in the United States: Causes, Symptoms, and Prevention

The Centers for Disease Control and Prevention (CDC) is a trusted government organization in the United States, dedicated to protecting the health and safety of the American people. As a .gov website, the CDC provides credible information on critical health issues, enhances health decisions, and promotes healthy living through strong partnerships with local, national, and international organizations. The CDC has recently reported a substantial increase in domestically acquired cyclosporiasis cases in multiple U.S. states, with 1,645 confirmed domestic cases and over 5,100 potential cases requiring further analysis. This is significantly higher than the 249 cases reported nationally by this same time last year. The CDC, in collaboration with the U.S. Food and Drug Administration (FDA) and state and local health departments, is working tirelessly to investigate multistate outbreaks of Cyclospora infections and identify the sources of illness.

Cyclosporiasis is a gastrointestinal illness caused by the microscopic parasite Cyclospora, which can be transmitted through the consumption of contaminated food or water. This illness is not usually spread directly from person to person and is often underdiagnosed and underreported. The true number of illnesses is likely higher than what has been reported to the CDC. Previous outbreaks have been linked to consuming contaminated fresh produce, and the CDC considers May 1-August 31 the annual cyclosporiasis season. Case counts typically rise during spring and summer months, with symptoms beginning about 1 week after exposure. The onset of symptoms can occur 2-14 days after being exposed, and the most common symptoms include watery diarrhea, loss of appetite, weight loss, bloating, nausea, and fatigue.

Symptoms of cyclosporiasis can be severe, but are not usually life-threatening. However, complications can include malabsorption, cholecystitis, and reactive arthritis. Laboratory detection of Cyclospora in stool can be challenging, even in symptomatic patients, and standard ova and parasite exams might not detect it reliably. Clinicians should specifically request diagnostic testing for Cyclospora when it is clinically suspected. The CDC has posted an investigation notice about an outbreak with more than 400 cases in at least four U.S. states that appear to be epidemiologically linked, suggesting that there could be a common source of these infections. As the investigation continues, the CDC is working closely with FDA and state health authorities to identify the sources of illness and prevent further outbreaks.

Since May 1, 1,645 lab-confirmed cases were reported to the CDC in people who acquired cyclosporiasis in the United States. Cases were reported by 34 states, with case-patients developing illness after eating food in the United States and not reporting any travel during the previous 14 days. The case-patients ranged in age from 2-95 years, with a median age of 44 years, and 56% were female. Of the 1,645 case-patients with information available, 141 (9%) were hospitalized, and no deaths have been reported. This is substantially higher than the 249 cases reported nationally from May 1-July 16, 2025. The CDC is urging clinicians, laboratorians, and public health practitioners to be aware of the increasing number of cyclosporiasis cases and to take necessary steps to support recognition, diagnosis, and reporting.

The CDC is taking a proactive approach to addressing the cyclosporiasis outbreak, working closely with state and local health authorities to investigate outbreaks and identify the sources of illness. The agency is also providing guidance to clinicians and laboratorians on diagnostic testing and treatment options. As the investigation continues, the CDC will provide updates on the outbreak and offer recommendations for preventing and controlling the spread of cyclosporiasis. The CDC emphasizes the importance of proper food handling and preparation practices to prevent the transmission of Cyclospora. Consumers can reduce their risk of infection by washing their hands frequently, especially after using the bathroom and before handling food, and by washing fruits and vegetables thoroughly before consumption.

The U.S. Department of Health and Human Services is committed to protecting the health and safety of the American people, and the CDC is playing a critical role in addressing the cyclosporiasis outbreak. The CDC's Health Alert Network (HAN) provides urgent notifications about public health incidents and emerging health threats, and the agency is working closely with state and local health authorities to respond to the outbreak. As the situation continues to evolve, the CDC will provide updates and guidance to clinicians, laboratorians, and public health practitioners to support recognition, diagnosis, and reporting of cyclosporiasis cases. The CDC's efforts to address the cyclosporiasis outbreak demonstrate the agency's commitment to protecting the health and safety of the American people and its role as a trusted leader in public health.

In conclusion, the cyclosporiasis outbreak in the United States is a significant public health concern, with a substantial increase in domestically acquired cases reported in multiple states. The CDC is working tirelessly to investigate outbreaks, identify the sources of illness, and prevent further outbreaks. Clinicians, laboratorians, and public health practitioners must be aware of the increasing number of cyclosporiasis cases and take necessary steps to support recognition, diagnosis, and reporting. By working together, we can reduce the risk of infection and protect the health and safety of the American people. The CDC will continue to provide updates and guidance on the outbreak, and it is essential to stay informed and take proactive steps to prevent the spread of cyclosporiasis.

Looking ahead, it is crucial to address the root causes of the cyclosporiasis outbreak and to develop strategies for preventing and controlling the spread of Cyclospora. The CDC will continue to work closely with state and local health authorities, as well as with the FDA, to investigate outbreaks and identify the sources of illness. The agency will also provide guidance to clinicians and laboratorians on diagnostic testing and treatment options. Additionally, the CDC will emphasize the importance of proper food handling and preparation practices to prevent the transmission of Cyclospora. By taking a proactive and collaborative approach, we can reduce the risk of infection and protect the health and safety of the American people.

The CDC's efforts to address the cyclosporiasis outbreak demonstrate the agency's commitment to protecting the health and safety of the American people. The CDC's role as a trusted leader in public health is crucial in responding to emerging health threats, and the agency's work to investigate outbreaks, identify the sources of illness, and prevent further outbreaks is essential to reducing the risk of infection. As the situation continues to evolve, it is essential to stay informed and take proactive steps to prevent the spread of cyclosporiasis. The CDC will continue to provide updates and guidance on the outbreak, and it is crucial to follow the agency's recommendations to reduce the risk of infection and protect the health and safety of the American people.

In the future, it is likely that the CDC will continue to play a critical role in addressing the cyclosporiasis outbreak and in developing strategies for preventing and controlling the spread of Cyclospora. The agency's work to investigate outbreaks, identify the sources of illness, and prevent further outbreaks will be essential to reducing the risk of infection and protecting the health and safety of the American people. Additionally, the CDC's emphasis on proper food handling and preparation practices will be crucial in preventing the transmission of Cyclospora. By working together and taking a proactive and collaborative approach, we can reduce the risk of infection and protect the health and safety of the American people.