Multistate outbreak of Listeriosis – Investigation update

In interviews, ill persons answered questions about foods consumed and other exposures in the month before becoming ill. All patients in Maryland reported consuming soft or semi-soft Hispanic-style cheese and all shopped at different locations of the same Hispanic-style local food store chain (Chain A). Testing of cheese products collected from Chain A stores was performed in Maryland and Virginia.

Virginia’s Division of Consolidated Laboratory Services (DCLS) identified Listeria monocytogenes in a sample of Caujada en Terron (fresh cheese curd) collected by the Virginia Department of Agriculture and Consumer Services (VDACS) from a Chain A store. The strain isolated from this product was indistinguishable by PFGE from the Listeria strainisolated from the 8 patients (outbreak strain). This cheese was produced by Roos Foods of Kenton, Delaware and was later repackaged in the Chain A store. VDACS issued a press releaseExternal Web Site Icon on February 15, 2014, instructing persons who purchased this product not to consume the cheese and to discard any remaining product.

VDACS subsequently collected pre-packaged Caujada en Terron produced by Roos Foods from Chain A that was not repackaged in the store. On February 21, the Virginia DCLS identified the outbreak strain of Listeria monocytogenes from these pre-packaged samples; a consumer advisoryExternal Web Site Icon was issued on February 21. Whole-genome sequencing will be performed on these isolates. In addition, the Maryland Department of Health and Mental Hygiene tested samples of pre-packaged cheese products purchased at Chain A stores. Cultures of those products produced by Roos Foods grew the outbreak strain of Listeria monocytogenes; whole genome sequencing of this strain will be performed. On February 19, the Maryland Department of Health and Mental Hygiene issued a warning to consumersExternal Web Site Icon to not eat any cheese products made by Roos Foods. This warning stated that Roos Foods cheese products are sold under brand names Santa Rosa de Lima, Amigo, Mexicana, Suyapa, La Chapina, and La Purisima Crema Nica. The District of Columbia issued a similar warningExternal Web Site Icon to consumers on February 20.

On February 23, Roos Foods voluntarily recalled all lots of its Cuajada En Terron, Cuajada/Cuajadita Cacera, Cuajada Fresca, Queso Fresca Round, and Queso Dura Viejo hard cheeses marketed under its Mexicana, Amigo, and Santa Rosa De Lima brands. These cheeses were manufactured or repacked by Roos. Roos Foods also recalled Queso Fresco marketed under the Anita brand. These products were distributed through retail stores in Maryland, Virginia, and the District of Columbia, including many retail stores other than Chain A.

FDA issued a notice of this recallExternal Web Site Icon on February 23 with advice to consumers, retailers, and restaurants.

Three of five adults associated with this outbreak are known to have consumed a cheese produced by Roos Foods. Health officials are continuing to investigate patients’ illnesses, including the exact type of cheese consumed.