Listeria outbreaks are often linked to soft cheese, usually made by small facilities. The 2014 outbreak associated with Oasis Brands soft cheeses and the current outbreak linked to Queseria Bendita soft cheeses are two cases in point.
There are several reasons for these outbreaks: small vendors may not have the experience or training to understand the risks inherent in making their product. These cheeses have higher pH than aged cheese and a high moisture content, which makes them quite susceptible to contamination. And third, Listeria monocytogenes bacteria is everywhere and it is hardy, growing at refrigerator temperatures and quite difficult to kill.
The outbreak in 2014 was never definitely linked to Oasis brand cheeses, but Listeria strains isolated from quesito casero cheese produced by Oasis Brands was “highly related” to sequences of Listeria strains isolated from patients. And environmental samples found Listeria monocytogenes at the production facility. Oasis Brands ceased all manufacturing of all products after the outbreak was discovered.
The five ill persons were from: Georgia (1), New York (1), Tennessee (2), and Texas (1). One person who lived in Tennessee died. Four of the five ill persons was hospitalized. And three illnesses were related to a pregnancy. One newborn was diagnosed with the illness. All of the sick people were Hispanic and reported eating Hispanic-style soft cheese.
The cheese could still be in consumer’s homes. Three recalls were issued during the course of the investigation. Oasis brands of quesito casero and cuajada en hoja were recalled. In October, Lacteos Santa Martha brand cheeses and one HonduCrema brand product were recalled. If you purchased these products, do not eat them. Discard in a sealed container, wash your hands thoroughly, then clean your fridge with a mild bleach solution to kill bacteria.
When the outbreak was first discovered in the summer of 2014, FDA and Virginia’s Division of Consolidated Laboratory Services performed pulsed field-gel electrophoresis (PFGE) and whole genome sequencing (WGS) on the isolates from the cheese samples and the environmental samples. Those methods were also used on samples taken from patients. The whole genome sequences from the five patients were also “highly related” to sequences of the Listeria strain found in the cheese.
The symptoms of a Listeria infection include flu-like fever and muscle aches, upset stomach or diarrhea, stiff neck, headache, loss of balance, and confusion. Pregnant women may be only mildly sick, but listeriosis can cause miscarriage, stillbirth, and a serious infection in the newborn baby. If you ate soft cheeses and have experienced these symptoms, please see a doctor immediately for treatment.