Domestically Acquired Cases of Cyclosporiasis — United States, May–August 2021

Last Updated SEPTEMBER 30, 2021 4:00 PM EDT

Cyclosporiasis illnesses are reported year-round in the United States. However, during the spring and summer months there is often an increase in cyclosporiasis acquired in the United States (i.e., “domestically acquired”). The exact timing and duration of these seasonal increases in domestically acquired cyclosporiasis can vary, but reports tend to increase starting in May. In previous years the reported number of cases peaked between June and July, although activity can last as late as September. The overall health impact (e.g., number of infections or hospitalizations) and the number of identified clusters of cases (i.e., cases that can be linked to a common exposure) also vary from season to season. Previous U.S. outbreaks of cyclosporiasis have been linked to various types of fresh produce, including basil, cilantro, mesclun lettuce, raspberries, and snow peas.

At a Glance
  • Illnesses: 1020
  • Hospitalizations: 70
  • Deaths: 0
  • States reporting cases: 36


CDC, along with state and federal health and regulatory officials, monitor cases of cyclosporiasis in the United States in the spring and summer months to detect outbreaks linked to a common food source. However, many cases of cyclosporiasis cannot be directly linked to an outbreak, in part because of the lack of validated laboratory “fingerprinting” methods needed to link cases of Cyclospora infection. Officials use questionnaires to interview sick people to determine what they ate in the 14-day period before illness onset. If a commonality is found, CDC and partners work quickly to determine if a contaminated food product is still available in stores or in peoples’ homes and issue advisories.

Final Update

  • In 2021, multiple outbreaks of cyclosporiasis cases associated with different restaurants or events were investigated by state public health authorities, CDC, and FDA.
    • CDC investigated two large multistate outbreaks of cyclosporiasisexternal icon, one including 40 illnesses and one with 130 illnesses, in which ill people reported eating various types of leafy greens. State officials and FDA conducted traceback investigations for these two outbreaks, but a specific type or grower of leafy greens was not identified as the source of either outbreak.
  • As of September 28, 2021, 1,020 laboratory-confirmed cases of cyclosporiasis in people who had no history of international travel during the 14-day period before illness onset have been reported to CDC by 37 jurisdictions, including 36 states and New York City, since May 1, 2021.
    • The median illness onset date is June 25, 2021 (range: May 1–August 31, 2021).
    • At least 70 people have been hospitalized; no deaths have been reported.

September 30, 2021

Geographic Distribution of Reported Cases of Domestically Acquired Cyclosporiasis—May 1 to August 31, 2021*


* Data are current as of 09/28/2021 (9:00am EDT). States/jurisdictions highlighted on the map have each reported at least one case. New York State includes case reports from New York City. 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.



Previous Updates

Page last reviewed: September 30, 2021