2014 Outbreak of Listeria Infections Linked to Oasis Brands, Inc. Cheese

On July 28, 2014, Virginia’s Division of Consolidated Laboratory Services (DCLS) identified Listeria monocytogenes in quesito casero, a type of unaged soft cheese made from pasteurized milk, produced by Oasis Brands, Inc. and collected during routine sampling. On August 4, 2014, Oasis Brands, Inc. voluntarily recalled quesito casero. On August 1, 2014, the U.S. Food and Drug Administration (FDA) began inspections at the firm’s processing facility in Miami, Florida. FDA subsequently collected environmental samples at the production facility; these samples yielded Listeria monocytogenes. As a result of these findings, on October 6, 2014, Oasis Brands, Inc. expanded the recall to include cuajada en hoja (fresh curd). On October 16, 2014, Oasis Brands, Inc. announced an additional recall of various Lacteos Santa Martha and one HonduCrema brand cheese and dairy products. At this time, Oasis Brands, Inc. has ceased manufacturing of all products, including the recalled products. 

FDA and Virginia DCLS performed pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) on the isolates from cheese (quesito casero) and environmental samples to further characterize the Listeria. Compared with PFGE, WGS provides a clearer distinction of genetic differences between bacteria strains. Strains that are highly related by WGS are more likely to have come from a common source.

Public health investigators used PFGE and WGS to identify cases of illness that were caused by highly related strains and therefore may have been acquired through consumption of these recalled products. They used data from PulseNet, the national subtyping network of state and local public health laboratories, CDC, and federal food regulatory laboratories that performs molecular surveillance of foodborne infections. 

Whole-genome sequences of the Listeria monocytogenes strains isolated from five ill persons were found to be highly related to sequences of the Listeria strain isolated from quesito casero cheese produced by Oasis Brands, Inc. These ill persons have been reported from four states: Georgia (1), New York (1), Tennessee (2), and Texas (1).  The first person became ill in September 2013, and four more recent illnesses occurred during June through October 2014.

Four of the five ill persons were hospitalized. Three illnesses were related to a pregnancy – one of these was diagnosed in a newborn. The two other illnesses occurred among adults. One death was reported in Tennessee. All ill persons were reported to be of Hispanic ethnicity. All five ill persons reported consuming Hispanic-style soft cheese in the month before becoming ill. Two persons who were able to answer questions about specific varieties of Hispanic-style soft cheeses reported consuming quesito casero, though neither could remember the brand.

The high degree of genetic similarity between isolates from ill persons and recalled cheese isolates showed that food contaminated with this strain of Listeria monocytogenes can cause serious illness. Although limited information was available about the specific cheese products consumed by ill persons, the whole genome sequencing findings, together with the cheese consumption history of the patients, suggested that these illnesses could have been related to products from Oasis Brands, Inc.

This particular investigation is over. However, the recalled products may still be in peoples’ homes. Consumers unaware of the recall could continue to eat these products and possibly get sick. Listeria is an important cause of human illness in the United States. More information about Listeria and steps people can take to reduce their risk of infection can be found on the CDC Listeria Web Page.

Final Case Count Update

A total of 5 ill persons infected with Listeria monocytogenes were reported from 4 states since June 2014. Since the initial announcement on October 29, 2014, 2 additional ill persons were reported from Georgia (1) and Tennessee (1).

Illness onset dates ranged from September 2013 to October 2014. Four of the five ill persons were hospitalized. One death was reported in Tennessee. Three illnesses were related to a pregnancy – one of these was diagnosed in a newborn. All ill persons were reported to be of Hispanic ethnicity and reported consuming Hispanic-style soft cheese. Two persons who were able to answer questions about specific varieties of Hispanic-style soft cheeses reported consuming quesito casero, though neither could remember the brand.

This investigation appears to be over. However, Listeria is still an important cause of human illness in the United States. More information about Listeria, and steps people can take to reduce their risk of infection, can be found on the CDC Listeria Web Page.

Investigation

On July 28, 2014, Virginia’s Division of Consolidated Laboratory Services (DCLS) identified Listeria monocytogenes in quesito casero, a type of unaged soft cheese, produced by Oasis Brands, Inc. and collected during routine sampling. On August 4, 2014, Oasis Brands, Inc. voluntarily recalled quesito casero. On August 1, 2014, the U.S. Food and Drug Administration (FDA) began inspections at the firm’s processing facility in Miami, Florida. FDA subsequently collected environmental samples at the production facility; these samples yielded Listeria monocytogenes. As a result of these findings, on October 6, 2014, Oasis Brands, Inc. expanded the recall to include cuajada en hoja (fresh curd). On October 16, 2014, Oasis Brands, Inc. announced an additional recall of various lots of Lacteos Santa Martha products.

FDA and Virginia DCLS performed pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) on the isolates from cheese (quesito casero) and environmental samples to further characterize the Listeria. Compared with PFGE, WGS provides a clearer distinction of genetic differences between bacteria strains. Strains that are highly related by WGS are more likely to have come from a common source.

Public health investigators used PFGE and WGS to identify cases of illness that were caused by highly related strains and therefore may have been acquired through consumption of these recalled products. They used data from PulseNet, the national subtyping network of state and local public health laboratories, CDC, and federal food regulatory laboratories that performs molecular surveillance of foodborne infections.

Whole-genome sequences of the Listeria monocytogenes strains isolated from three ill persons were found to be highly related to sequences of the Listeria strain isolated from quesito casero cheese produced by Oasis Brands, Inc. These ill persons have been reported from three states: New York (1), Tennessee (1), and Texas (1). The first person became ill on September 13, 2013, and two more recent illnesses occurred on June 25, 2014, and August 13, 2014.

All three ill persons were hospitalized. One of the illnesses was related to a pregnancy and was diagnosed in a newborn. The two other illnesses occurred among adults. One death was reported by Tennessee. All ill persons were reported to be of Hispanic ethnicity. All three ill persons reported consuming Hispanic-style soft cheese in the month before becoming ill. The two persons who were able to answer questions about specific varieties of Hispanic-style soft cheeses both reported consuming quesito casero, though neither could remember the brand.

The high degree of genetic similarity between isolates from ill persons and recalled cheese isolates shows that food contaminated with this strain of Listeria monocytogenes can cause serious illness. Although limited information is available about the specific cheese products consumed by ill persons, the whole genome sequencing findings, together with the cheese consumption history of the patients suggests that these illnesses could have been related to products from Oasis Brands, Inc.

CDC, the states involved, and FDA continue to work closely on this ongoing investigation, and new information will be provided when available.