Virginia Aguado Lorenzo from Pamplona has carried out a study to analyze the presence of listeria monocytogenes in various foods consumed by the people of Navarre. This pathogenic microorganism is mainly transmitted through food and causes listeriosis, a disease of leave incidence, but of serious consequences, with associated mortality fees of 25-30%. With this study, directed by Professor Isabel García Jalón, Virginia Aguado has obtained the Degree of Doctor of Science from the University of Navarra with the maximum grade, A cum laude.

The results obtained indicate a wide distribution of the bacterium in food," he says. Its presence in meats is very high; on the other hand, it has hardly been found in vegetables". According to the new doctor, "raw products do not pose any health risk, since they will undergo heat treatment before consumption. More important from the sanitary point of view is the presence of listeria detected in products for direct consumption, such as smoked salmon or cooked meat products, although the levels found are not high enough to cause the disease".

Slicing, a critical point of risk

The researcher from the University of Navarra stresses that the study has shown, on the one hand, the existence of clones specially adapted to survive in certain foods; and on the other hand, cross-contamination between different products during handling at points of sale or at home. "Specifically, the slicing operation is a critical point of risk in the spread of contamination".

Therefore, the results "highlight the need to monitor this pathogen in order to establish the risk points and to be able to recommend to industries and food handlers the appropriate prevention and control measures for each case".

The absence of data, in Spain and in Navarra, about the presence and distribution of listeria monocytogenes led Virginia Aguado and the department of Microbiology of the University of Navarra to consider this study, in which a wide variety of raw and treated foods have been investigated.

Risk groups

Regarding listeriosis, the new doctor explains that "it affects developed countries because it is directly related to food habits. Thus, products that are purchased prepared and consumed without prior culinary treatment are those that present the greatest risk in the transmission of the bacterium, since it can multiply during storage in refrigerated conditions and even under vacuum, up to dangerous levels for the consumer. In fact, the most serious outbreaks of the disease have been due to soft cheeses and cooked meat products".