CDC Warns of Increased Cases of Cyclosporiasis

Cyclosporiasis is an intestinal illness caused by a parasite and transmitted through consumption of contaminated food or water.

The CDC has identified an increase in reported cases of cyclosporiasis, according to a health advisory issued by the CDC Health Alert Network.

As of August 2, 2017, 206 cases of infection have been reported to the CDC in individuals who have been infected in the United States and became ill on or after May 1, 2017, which is higher than the number of cases reported by this date in 2016. The cases have been reported from 27 states, and 18 cases reported hospitalization. No deaths have occurred.

Cyclosporiasis, which is an intestinal illness caused by a parasite, is transmitted through consumption of food or water contaminated with the Cyclospora cayetanensis parasite. However, direct person-to-person transmission is not possible.

The most common symptom of cyclosporiasis is watery diarrhea, which can be profuse. Other symptoms include anorexia, fatigue, weight loss, nausea, flatulence, abdominal cramping, and myalgia. Symptoms may begin an average of 7 days after infection, and if untreated, the illness can last from a few days to a month or longer.

Cyclosporiasis is treated with trimethoprim/sulfamethoxazole (TMP/SMX). There have been no effective alternative treatments identified.

According to the CDC, investigations to identify a potential source of infection are ongoing and it is too early to determine whether cases of infection in different states are related to each other.

The CDC recommends health care providers to:

  • Consider a diagnosis of cyclosporiasis in patients who have prolonged or remitting-relapsing diarrheal illness.
  • Specifically order testing for Cyclospora if indicated, whether testing is requested by ova and parasite examination, by molecular methods, or by a gastrointestinal pathogen panel test. The CDC notes that several stool specimens may be required because Cyclospora oocysts may shed intermittently and at low levels.
  • Report cases to local health departments.


Increase in reported cases of Cyclospora cayetanensis infection, United States, Summer 2017 [news release]. CDC Health Alert Network. CDC’s website. Accessed August 8, 2017.

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