On Oct. 19, 2011, the Food and Drug Administration released a document that provides an overview of factors that potentially contributed to the contamination of fresh, whole cantaloupe with the pathogen Listeria monocytogenes, which was implicated in a 2011 multi-state outbreak of listeriosis.
In early September 2011, the FDA, in conjunction with the Centers for Disease Control and Prevention (CDC) and state health departments, began to investigate a multi-state outbreak of listeriosis. Early in the investigation, cantaloupes from Jensen Farms in the southwest region of Colorado were implicated in the outbreak.
On Sept. 10, 2011, FDA, along with Colorado state officials, conducted an inspection at Jensen Farms during which FDA collected multiple samples, including whole cantaloupes and environmental (non-product) samples from within the facility, for laboratory culturing to identify the presence of Listeria monocytogenes. Of the 39 environmental samples collected from within the facility, 13 were confirmed positive for Listeria monocytogenes with pulsed-field gel electrophoresis (PFGE) pattern combinations that were indistinguishable from three of the four outbreak strains collected from affected patients. Cantaloupe collected from the firm's cold storage during the inspection was also confirmed positive for Listeria monocytogenes with PFGE pattern combinations that were indistinguishable from two of the four outbreak strains.
As a result of the isolation of outbreak strains of Listeria monocytogenes in the environment of the packing facility and whole cantaloupes collected from cold storage, and the fact that this is the first documented listeriosis outbreak associated with fresh, whole cantaloupe in the United States, FDA initiated an environmental assessment in conjunction with Colorado state and local officials. FDA, state and local officials conducted the environmental assessment at Jensen Farms on Sept. 22-23, 2011. The environmental assessment was conducted to gather more information to help FDA identify the factors that potentially contributed to the introduction, growth or spread of the Listeria monocytogenes strains that contaminated the cantaloupe.
FDA identified the following factors as those that most likely contributed to the introduction, spread and growth of Listeria monocytogenes in the cantaloupes.
• There could have been low level sporadic Listeria monocytogenes in the field where the cantaloupe were grown, which could have been introduced into the packing facility.
• A truck used to haul culled cantaloupe to a cattle operation was parked adjacent to the packing facility and could have introduced contamination into the facility.
• The packing facility's design allowed water to pool on the floor near equipment and employee walkways;
• The packing facility floor was constructed in a manner that made it difficult to clean
• The packing equipment was not easily cleaned and sanitized; washing and drying equipment used for cantaloupe packing was previously used for postharvest handling of another raw agricultural commodity.
• There was no pre-cooling step to remove field heat from the cantaloupes before cold storage. As the cantaloupes cooled there may have been condensation that promoted the growth of Listeria monocytogenes.
FDA's findings regarding this particular outbreak highlight the importance for firms to employ good agricultural and management practices in their packing facilities as well as in growing fields. FDA recommends that firms employ good agricultural and management practices recommended for the growing, harvesting, washing, sorting, packing, storage and transporting of fruits and vegetables sold to consumers in an unprocessed or minimally processed raw form.
FDA has issued a warning letter to Jensen Farms based on environmental and cantaloupe samples collected during the inspection. FDA's investigation at Jensen Farms is still considered an open investigation.
Jensen Farms' recall
Jensen Farms voluntarily recalled its whole cantaloupes on Sept. 14 in response to the multi-state outbreak of listeriosis. Cantaloupes from other farms have not been linked to this outbreak.
FDA has successfully audited the majority of Jensen Farms' direct and secondary accounts. The recalled cantaloupes were produced from the end of July to Sept. 10, 2011. Given that the Jensen Farms' recall has been in effect for more than a month and that the shelf life of a cantaloupe is approximately two weeks, it is expected that all of the recalled whole Jensen Farms cantaloupes have been removed from the marketplace.
FDA has verified that the following states received recalled cantaloupes directly from Jensen Farms: Arizona, Arkansas, Colorado, Idaho, Illinois, Indiana, Kansas, Louisiana, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Dakota, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Wisconsin and Wyoming. There is no indication of foreign distribution.