Purpose: In response, a food safety surveillance program was initiated by State Hygienic Laboratory and Iowa Department of Inspection and Appeals to test fresh produce (retail and farmers markets) for both parasites.
Methods: Two real-time polymerase chain reaction (qPCR) assays were developed for the rapid and sensitive detection of Cryptosporidium parvum/hominis and Cyclospora cayetanensis in leafy green produce. The Cyclospora cayetanensis PCR targets the 18S rRNA gene. The C. parvum/hominis assay is a multiplex PCR assay that amplifies a Cryptosporidium specific gene. The performance of the PCR assays on leafy green produce was evaluated by inoculation with oocysts and processed according to protocol. The methods are sensitive and able to detect C. cayentanenis and C. parvum/hominis parasites in leafy green products inoculated with 60 and 40 oocysts 100% of the time, respectively.
Results: Surveillance testing for C. cayetanensis was conducted for 105 packaged leafy green products from 15 different manufactures that were obtained from 13 Iowa grocery stores. C. parvum/hominis was tested for in 98 locally grown leafy green products from 37 different vendors/farms obtained from five different farmers markets. No parasites were detected in the 203 samples.
Significance: The 2013 Cyclospora outbreak suggested that the incidence of these parasites in produce may be of greater significance than previously recognized and sensitive real-time assays were needed. Surveillance testing will continue in 2016.