CDC HEALTH UPDATE
May 24, 2004

Foodborne outbreaks of cyclosporiasis in Texas and Illinois, February 2004

Investigations continue, but no evidence for ongoing transmission

Public health officials at the local, state, and federal levels continue to investigate clusters of cases of Cyclospora cayetanensis infection (cyclosporiasis) associated with events held in Texas and Illinois in February 2004. Approximately 95 cases of cyclosporiasis have been identified among attendees of the events (36 laboratory-confirmed cases and 59 clinically defined or probable cases). Analysis of epidemiologic data continues, and trace-back investigations of potentially involved food items have been initiated by the Food and Drug Administration (see FDA press release, May 21, 2004). It is not yet known whether the same item(s) caused the outbreaks in Texas and Illinois and whether these outbreaks are linked. Most importantly, despite heightened surveillance for cases of cyclosporiasis throughout the United States during the last few months, no clusters of cases besides those in Texas and Illinois have been identified. This could suggest that transmission of infection from the food item(s) that caused these outbreaks may no longer be occurring.

Texas
Two clusters of cases have been identified, which were associated with meals eaten on February 6 and 7 at a restaurant in Irving (near Dallas). CDC was first notified of the outbreak on February 27 and confirmed the diagnosis of Cyclospora infection in the index case-patient’s stool specimen on March 4.

Illinois
Several clusters of cases associated with events held in DuPage County on February 24, 25, and 26 have been identified. The same caterer prepared the food served at all of the events. CDC was first notified of the outbreak on March 26 and confirmed the diagnosis of Cyclospora infection on April 5.

Perspective
The foodborne outbreaks of cyclosporiasis previously investigated in the United States have been linked to various types of fresh produce, such as basil, raspberries, and mesclun lettuce (also known as spring mix or baby greens). For the outbreaks for which trace-back investigations to determine the source of the implicated produce were conducted, the produce either definitely was or could have been imported. As always, fresh produce should be thoroughly washed before it is eaten. Because Cyclospora can adhere to food items, washing produce should reduce, but may not eliminate, the risk for infection.

The types of fresh produce served at the events in Texas and Illinois included basil and mesclun lettuce. However, investigations are ongoing to determine what food item(s) was associated with illness, where it was grown and distributed, and whether the outbreaks in the two states are related. The investigations have been complicated by the facts that many of the food items served at the events included multiple types of fresh produce, and certain types of produce were included in multiple food items.

Although no evidence suggestive of ongoing transmission has been reported to CDC, health-care providers evaluating persons with symptoms consistent with cyclosporiasis (see below) should request that stool specimens be tested for this parasite. Stool examined for ova and parasites usually is not examined for Cyclospora unless such testing is specifically requested.

Modes of Transmission, Incubation Period, and Symptoms
Cyclospora is spread by persons ingesting something (e.g., water or food) that was contaminated with infected stool. Cyclospora needs time (days or weeks) after being excreted in stool, into the environment, to become infectious. Therefore, it is unlikely that Cyclospora is passed directly from one person to another. It also is unlikely that an infected food handler, who prepares food eaten within a few days, could cause a foodborne outbreak of cyclosporiasis.

The incubation period between becoming infected and developing symptoms averages 1 week. This long interval leads to delays in detection of cases and outbreaks. Cyclospora infects the small intestine and typically causes watery diarrhea, with frequent, sometimes explosive, bowel movements. Other symptoms can include loss of appetite, substantial loss of weight, bloating, increased flatus, stomach cramps, nausea, vomiting, muscle aches, low-grade fever, and fatigue. If untreated, illness may last for a few days to a month or longer, with a remitting-relapsing course.

Treatment
Trimethoprim/sulfamethoxazole (TMP/SMX) has been shown in a placebo-controlled trial to be effective treatment of Cyclospora infection. Adults should receive TMP 160 mg plus SMX 800 mg (one double-strength tablet) orally, twice a day for 7 days. Some patients may benefit from longer courses of therapy. Alternative treatments for persons allergic to sulfa drugs have not yet been identified.

Cases of cyclosporiasis unrelated to foreign travel may be associated with a new outbreak. Health-care providers and laboratory staff should report suspect and confirmed cases of cyclosporiasis to their local and state health departments. State health departments should report cases to CDC (770) 488-7775 / 7319 / 7772.

For more information about cyclosporiasis, see: http://www.cdc.gov/ncidod/dpd/parasites/cyclospora/default.htm

Categories of CDC Health Alert messages:
Health Alert: conveys the highest level of importance; warrants immediate action or attention.
Health Advisory: provides important information for a specific incident or situation; may not require immediate action.
Health Update: provides updated information regarding an incident or situation; unlikely to require immediate action.

Go Back to where you were.