Officials at the Centers for Disease Control and Prevention in Atlanta said at least 18 people were reportedly hospitalized in three states from the nasty stomach bug.
"No food items have been implicated to date, but public health authorities are pursuing all leads. Previous outbreak investigations have implicated various types of fresh produce," a statement by the CDC said.
Since no source has been identified, health officials recommend consumers should always practice safe food handling and wash hands, utensils and surfaces with hot, soapy water before and after handling food. Fresh produce should be thoroughly washed before it is eaten, officials said.
Most past infections were associated with international travel or contaminated basil, mesclun lettuce, raspberries and snow peas.
Cases in this outbreak are defined as laboratory-confirmed Cyclospora in a person who became ill in June or July and had no history of travel outside the United States or Canada during the 14 days prior to onset of illness.
The number of cases identified were: 138 in Iowa, 71 in Texas, 70 in Nebraska, 23 in Florida, four in New York City, three in Wisconsin, three in Georgia, two in Missouri, and one in Arkansas, Connecticut, Illinois, Kansas, Minnesota, New Jersey and Ohio.
To date, the CDC confirmed 33 cases of Cyclospora infection in CDC laboratories. One of the cases was confirmed via telediagnosis. The CDC encourages laboratories to obtain confirmation of cases using telediagnosis, which allows for rapid laboratory confirmation.
State health laboratories may submit images to the CDC showing suspected Cyclospora oocysts -- a hardy, thick-walled spore -- captured from modified acid-fast stained smears or from wet mounts examined by UV fluorescence microscopy. Instructions for submitting images for telediagnosis are found on the DPDx site at: http://www.dpd.cdc.gov/dpdx/Default.htm.