are milk products a usual source for listeria
Prior to widespread adoption of. pasteurization, bacterial infections such as diphtheria, scarlet fever and. tuberculosis were often linked to consumption of raw milk products. Routine. pasteurization has been highly effective in ensuring the safety of dairy products. Venereal transmission might also be possible. In. ruminants, listeriosis typically occurs after the consumption of contaminated silage or. other feed. For humans, contaminated food sources include raw meat and fish, unpasteurized dairy products and uncooked vegetables. L. monocytogenes has also. been found in processed foods that have become contaminated after processing, particularly soft cheeses, deli cold cuts, sliced or grated cheese, and ice cream. Listeriosis usually results from infection by Listeria monocytogenes, a Gram. positive rod in the family Listeriaceae. This organism is a facultative intracellular. pathogen. There are 13 serovars of L. monocytogenes. Some infected people may excrete L. monocytogenes in. the feces for several months, mothers of infected newborns. can shed the organism for 7 to 10 days after delivery, and. Listeria has been isolated from human milk. Nevertheless, person-to-person transmission (except for prenatal. transmission) is not usually seen. Listeria bacteria are common in nature. Listeria is a common presence in nature, found widely in such places as water, soil, infected animals, human and animal feces, raw and treated sewage, leafy vegetables, effluent from poultry and meat processing facilities, decaying corn and soybeans, improperly fermented silage, and raw (unpasteurized) milk. In adult dairy cattle, clinical signs often occur during periods of. reduced immune function such as the peri-parturient period. The risk period for. calves varies depending upon serotype (usually <14 days of age for S. typhimurium, 1 week to 6 months of age for S. dublin). The disease is spread. through fecal-oral transmission and is maintained within cattle populations by 1) carrier animals; 2) infected calves; 3) environmental contamination. Listeriosis is usually a serious problem only in. pregnant women, newborns, the elderly, and. immunocompromised or debilitated hosts. Pregnant women may experience either a mild, flu-like. syndrome with fever, chills, headache, slight dizziness or. gastrointestinal signs, or an asymptomatic infection. In a western study, seven of 205 (3.4%) cull dairy cows on tested. farms were positive for E. coli O157:H7.25 E. coli was found in 30.1% of 209. samples of cattle feed.26 While none of the samples were positive for O157:H7, fecal contamination of feedstuffs is a likely possibility for environmental. contamination. awareness of potential threats to human health from food products.1,2,3 Much of. the concern about foodborne disease is related to the changing nature of. outbreaks.4 Traditionally, outbreaks of foodborne disease were acute and highly. local in nature, often following a social event in a community. Foods commonly identified as sources of Listeria infection include improperly pasteurized fluid milk , cheeses ( particularly soft-ripened varieties , such as traditional Mexican cheeses , Camembert and ricotta ) , ice cream , raw vegetables , fermented raw-meat sausages , raw and cooked poultry , and cooked , ready-to-eat ( RTE ) sliced meats—often ...
Yes