METHODS: An epidemiological investigation was initiated to identify clusters of illness and potential food vehicles. The Incident Command System (ICS) was activated to manage resources, calls from the public and media inquiries. A state supplied case investigation form for cyclosporiasis was used for each reported case and food histories were collected in detail. Restaurant and event clusters were identified from case interviews utilizing a line list and meal items analyzed to identify common food items within each cluster. Restaurant site visits with managers, food purchasers, and chefs helped hone in on specific food ingredients by reviewing recipes and supplier invoices.
RESULTS: Sixty-seven confirmed cases and 20 probable cases of cyclosporiasis that had onsets between May 27, 2015 and August 26, 2015 were investigated. Disease clusters were identified at three restaurants, one local business cafeteria, two weddings and two graduations. Trace back investigation in Austin/Travis County converged on one produce supplier focusing on cilantro, basil, parsley and mint herbs.
CONCLUSIONS: Through trace back investigations conducted by state and federal agencies in partnership with local partners, the US Food and Drug Administration (FDA) placed an import ban on cilantro from Puebla, Mexico on July 28, 2015. Key strengths of our investigation were: ICS structure was used early in the investigation to streamline processes and prioritization; communication and strong relationships with state partners that supported investigation and collaboration; and a strong focus on cluster identification through targeted interviews.