Alexandra Esteves

By Cristina Saraiva, Juan García-Díez, Maria da Conceição Fontes and Alexandra Esteves

This work was conducted to present some studies that show the behavior of Listeria monocytogenes in meat, according to intrinsic and extrinsic factors. The understanding of factors that affect the survival and growth of L. monocytogenes in meat, such as temperature, pH, acid, salt, water activity or modified atmosphere packaging, is crucial to develop strategies for food operators to reduce and prevent Listeria contamination and growth. The knowledge of L. monocytogenes behavior according to its physiological and ecological characteristics, under all probable conditions, will support risk assessors to find strategies to control this ubiquitous bacteria in food industry and food service. The Regulation (EC) No 2073/2005, reviewed by the Regulation (EC) No 1441/2007, does not establish the limits for L. monocytogenes in fresh meat. However, it is generally accepted a level of 100 cells on fresh meat, except for some risk groups. Food business operators and authorities can use predictive microbiology models as important tools to model bacterial growth in quantitative microbial risk assessments.

Part of the book: Listeria Monocytogenes

By Carla Neves Machado, Leonor Orge, Isabel Pires, Adelina Gama, Alexandra Esteves, Ana Paula Mendonça, Ana Matos, Anabela Alves, Carla Lima, Estela Bastos, Fernanda Seixas, Filipe Silva, João Carlos Silva, Luis Figueira, Madalena Vieira-Pinto, Maria De Lurdes Pinto, Nuno Gonçalves-Anjo, Paula Tavares, Paulo Carvalho, Roberto Sargo and Maria Dos Anjos Pires

Among the transmissible spongiform encephalopathies (TSEs), chronic wasting disease (CWD) in cervids is now the rising concern within Europe. CWD will be outlined in this chapter gathering its epidemiology, transmission, diagnosis, genetics, and control. Prion diseases are fatal neurodegenerative diseases characterized by the accumulation of an abnormal isoform of the prion protein (PrPc), usually designated by PrPsc or prion. CWD is a prion disease of natural transmission affecting cervids detected mainly in North America. The first European case was detected in Norway, in 2016, in a wild reindeer; until April 2018, a total of 23 cases were described. The definite diagnosis is postmortem, performed in target areas of the brain and lymph nodes. Samples are first screened using a rapid test and, if positive, confirmed by immunohistochemistry and Western immunoblotting. It is not possible to establish a culling plan based on the genotype, once affected animals appear with all genotypes. However, some polymorphisms seem to result in longer incubation periods or confer a reduced risk. The control is not easy in captive cervids and even more in the wildlife; some recommendations have been proposed in order to understand the danger and impact of CWD on animal and public health.

Part of the book: Wildlife Population Monitoring