Review. Dairy farm management and production practices associated with the presence of Listeria monocytogenes in raw milk and beef

Abstract

Human listeriosis is a severe foodborne disease caused by Listeria monocytogenes. It is a zoonosis that represents a significant concern for the food industry due to the high mortality rate it causes and the fact that the organism is capable of growing at refrigeration temperatures. Dairy products and ready-to-eat meats are among the foods most often involved in listeriosis outbreaks. Listeria is a common contaminant in the dairy environment, both on the farm and in the processing plant. The main sources of L. monocytogenes in dairy farms are manure and improperly fermented silage. If silage crops are grown on contaminated land, a new cycle of silage contamination and faecal shedding by ruminants that consume such silage may ensue. High loads of L. monocytogenes produced in farm environments may thus represent a primary source for the introduction of this pathogen into the human food supply chain; dairy cows would represent a reservoir for the bacterium, and raw milk and beef would represent the main vehicles for its transmission from dairy farms to humans. Even if contamination originates in post-processing environments, contaminated raw foods may still represent a vehicle for introducing L. monocytogenes into food processing plants. Molecular typing methods have confirmed that common strains of L. monocytogenes are present in dairy farm-associated isolates and isolates from both human epidemic and sporadic cases. Pre-harvest (on-farm) control of listeriosis should be based mainly on the control of manure, silage, herd health and milking practices.Additional key words: animal reservoir; dairy primary production; environmental sources; food vehicles; listeriosis. ResumenRevisión. Tipos de gestión y producción de las granjas de ganado vacuno lechero relacionados con la presencia de Listeria monocytogenes en la leche y la carne La listeriosis humana es una grave enfermedad transmitida por alimentos y causada por Listeria monocytogenes. Se trata de una zoonosis que supone una gran preocupación para la industria alimentaria debido a su alta tasa de mortalidad y al hecho de que el microorganismo es capaz de crecer a temperaturas de refrigeración. Listeria es un contaminante habitual en las granjas y plantas de productos lácteos. En las granjas las fuentes principales de L. monocytogenes son el estiércol y los ensilados mal fermentados. Si la cosecha utilizada para producir ensilados procede de campos contaminados, puede comenzar un nuevo ciclo de contaminación de los ensilados y liberación del patógeno en las heces de los animales. El ganado vacuno lechero representa uno de los principales reservorios de este microorganismo y la leche y la carne representarían los principales vehículos para su transmisión desde la granja de producción de leche al ser humano. Incluso cuando la contaminación del alimento procede de etapas posteriores al procesado, los alimentos crudos contaminados también representan uno de los vehículos de entrada de L. monocytogenes en las plan-

Listeriosis in animals, its public health significance (food-borne zoonosis) and advances in diagnosis and control: a comprehensive review

“…Crucial factors for disease prevention include timely detection, keeping away/eliminating possible sources of infection, maintaining high hygiene/sanitation standards and following good management practices in poultry farms and poultry processing units, discarding infected poultry at entry level of processing plants, adapting appropriate disinfection measures with proper culling and quarantine/isolation of affected birds (Swaminathan 2001;Cutter & Henning 2003;Kosek-Paszkowska et al 2005;Malik & Vaidya 2005;Rossi et al 2008;Dhama et al 2012;Oh et al 2014). Control of listeriosis on a preharvest basis on farms should be based mainly on manure control, silage, health of herd and milking practices (Farber & Losos 1998;Borucki et al 2004;Antognoli et al 2009;Little et al 2009;Buckley & Reid 2010;Santorum et al 2012). Antibiotics usage in feed is of prophylactic value for prevention of listeriosis in poultry.…”

Genotypic and virulence characteristics of Listeria monocytogenes recovered from food items in Lebanon

“…This can occur during processing or packaging of the end product as demonstrated by a study done in Finland [25]. Furthermore, raw meat and some of the white 'Baladi' cheese isolates showed 100% clonal relatedness and belonged to the same subtype, which might be explained by cross-contamination between dairy and meat products in cattle farms [26]. Interestingly, two of the CDC controls used showed a high genomic similarity with the tested isolates.…”

Invading slugs ( A rion vulgaris) can be vectors for L isteria monocytogenes

“…; Santorum et al . ). Slugs find mammalian faeces attractive as food (Kozlowski ) and Arion ater is described as coprophagous (Shrewsbury and Barson ), a behaviour that can contribute to bacterial persistence.…”