Surveillance of Cyclosporiasis

Overview

Cyclosporiasis is a gastrointestinal illness caused by the microscopic parasite Cyclospora. Cyclosporiasis is a nationally notifiable disease and is reportable in 47 states, the District of Columbia, and New York City. For the states and U.S. territories in which it is not reportable, it is still important for healthcare providers and the public to inform local health departments about potential cases and clusters of cyclosporiasis so that they can take appropriate action to prevent additional cases.

How CDC monitors cases

CDC, along with state and federal health and regulatory officials, monitors laboratory-confirmed cases of cyclosporiasis year-round to detect outbreaks potentially linked to a common food source in the United States. Regular monitoring aids in swiftly identifying and investigating outbreaks in the United States. Cyclosporiasis can also be acquired when people eat or drink contaminated food or water during travel outside the United States. CDC uses molecular fingerprinting tools to help identify cyclosporiasis cases that may be part of outbreaks.

Case counts rise during the spring and summer months each year. The cyclosporiasis season in the United States is May 1 through August 31. Clusters of cyclosporiasis cases have been detected outside this range in some years. In 2026, the cyclosporiasis season began on May 1.

Cases acquired in the U.S.

May 1 - August 17, 2026:

^*47 states plus the District of Columbia and Puerto Rico

These people became sick in the United States and did not report any international travel during the 14 days before they got sick.

They ranged in age from 1  to  99  years, with a median age of 46, and 57% were female. The median illness onset date was July 7, 2026 (range from May 1 to August 13).

These data include the cases reported in the ongoing multistate outbreak linked to recalled iceberg lettuce. Multiple jurisdictions have reported an increase of cases compared with the same period in 2025.

CDC teams are working to collect, analyze, and provide data at the national level. State health departments may have more information about the situation in their jurisdictions.

Clusters of illness under investigation

CDC is investigating multiple clusters of cyclosporiasis, including the large multistate outbreak linked to processed iceberg lettuce from central Mexico. This multistate outbreak has contributed significantly to the increase in Cyclospora cases this year. Additionally, CDC and FDA are investigating at least six other clusters for which sources have not yet been confirmed. These clusters are listed on FDA's active investigation table. If sources are identified and there is public health action for consumers to take, CDC will issue outbreak notices for those clusters.

Case locations

Since May 1, 2026, 15,716 people have been reported with laboratory-confirmed cyclosporiasis acquired in the United States. The map shows where these people live. Potential Cyclospora infections are typically investigated by the state or local health department where people live, even if they were exposed to the parasite in another state. Cyclosporiasis cases may not be limited to these locations with known cases. The true number of people sick with cyclosporiasis is likely higher than the number reported. This is because some people recover without medical care and are not tested for Cyclospora.

Note: Hover over the map to see the range of cyclosporiasis cases for each state.

*These data include case data reported directly to the CDC Cyclospora program. Case counts may not match exactly with what is listed in the Nationally Notifiable Diseases Surveillance System tables. New York State includes case reports from New York City. In Pennsylvania, cases are reported voluntarily. Data are preliminary and subject to change. For questions related to the number of cases reported in each state, contact that state's health department.

Cases by date symptoms started

How we use epi curves

An epi curve helps public health investigators monitor an outbreak and understand whether illnesses continue to occur or have stopped. This information can guide decisions about public health actions.

Cases acquired outside the U.S.

These cases are in addition to those acquired in the United States.

May 1 - August 17, 2026:

These people became sick after eating food or drinking water while they were traveling outside the United States during the 14 days before they got sick.

They ranged in age from 10 months to 89 years, with a median age of 44, and 57% were female. The median illness onset date was June 24, 2026 (range from May 1 to August 8).

How CDC collects cyclosporiasis data

CDC collects data on cyclosporiasis through routine public health surveillance: clinicians and clinical laboratories report cases to local and state health departments according to their reporting practices. They send case information to CDC via the National Notifiable Diseases Surveillance System (NNDSS) and outbreak-specific reporting channels.

State and local health departments also conduct case investigations using standardized questionnaires (capturing clinical, demographic, and exposure information) and notify CDC when clusters or outbreaks are suspected. Jurisdictions may request patient interviews, stool specimens, and detailed laboratory testing results to support epidemiologic analyses and any molecular or reference testing.

CDC further partners with state public health laboratories, FDA, and other agencies to integrate laboratory data and food traceback information to help identify outbreak sources and inform prevention efforts.

How CDC investigates outbreaks

CDC works with state, local, and federal partners to combine patient interviews, food traceback through the supply chain, and laboratory testing to find the source of multistate outbreaks. Many foods investigated in outbreaks have multiple produce ingredients, like salsa or salads, making it difficult to narrow down to a single food item. In addition, the Cyclospora parasite is harder to track than many bacteria like Salmonella because whole genome sequencing isn't available for this pathogen. CDC uses genetic testing targeting specific markers on stool samples to identify groups of related cases. This helps investigators prioritize traceback and other actions to stop more illnesses.

Resources

• Reporting a Foodborne Disease Outbreak (general public)
• Report a Problem with Food
• Cyclosporiasis National Hypothesis Generating Questionnaire
• FDOSS Home | Foodborne Disease Outbreak Surveillance System (FDOSS)| CDC
  
• Foodborne Outbreak Surveillance Data
• Food and Water Precautions for Travelers | Yellow Book | CDC
• Symptoms of Cyclosporiasis | Cyclosporiasis | CDC