A recent study was able to provide more details on years of Listeria outbreaks linked to meat products from one company in Germany. The U.S. was one of 20 countries that received the company's meat products. 

The goal of the study was to verify and describe a cluster of listeriosis patients, and identify outbreak factors. The cluster was named "Sigma1." The journal Clinical Microbiology and Infection published the study. 

The outbreak had 39 cases between 2014-2019, and three people died. No further patients were announced after a recall of meat products and closure of the company in October 2019.

The U.S. was one of 20 countries that had received meat from the company, but none of the other countries and any illnesses reported. Researchers were surprised by this, citing the export volume of the German company's products, and long-term contamination factors in the production plant.