Notes on Cheese, Pasteurization, and Contamination
Agatha M. Thrash, M.D.
It is true that at the present time, the FDA requires cheeses made in this country to either be pasteurized, or else "unpasteurized cheese must be aged at 35° F for 60 days." Soft-ripened cheeses from unpasteurized milk is common in Europe and Mexico. (FDA CONSUMER, October 1983, p. 36)
In addition to the frequent appearance of imported unpasteurized soft cheeses, there is little cause to be complacent over practices in the U.S.
Listeriosis caused 84 deaths in California in 1985 due to consumption of Mexican soft cheeses. In Feb. 1986, 6 brands of imported French Brie were recalled when found contaminated with Listeria. In 1983, a Listeriosis outbreak in Massachusetts occurred from pasteurized whole or 2% milk, with 84 illnesses and 14 deaths. A Yersinia outbreak in pasteurized milk in Tennessee in 1983 sickened 172 people. (A recent article in the THE NEW ENGLAND JOURNAL OF MEDICINE reviewed Yersinosis, and emphasized the serious chronic illnesses resulting from it, including many cases of rheumatoid arthritis.)
In 1985, 16,000 cases of Salmonellosis occurred in 6 midwestern states, found due to contaminated low-fat milk. "There has been a proliferation of pipelines connecting raw unpasteurized and pasteurized storage and holding tanks in dairy plants. [These] present easy by-passes around the pasteurizer, making contamination possible."
"Inspection of soft cheese manufacturers (in the U.S.) have shown 'similar problems with respect to potential by-passes around the pasteurizer.'" They also found "defects in the pasteurization process, pathogenic organisms in the processing and storage areas, and discrepancies in pasteurization charts and other records, with 'lack of education and training of dairy employees.'" (FDA CONSUMER, April 1986, p. 14. "Dairy Safety")
"Raw milk cheeses have become popular, especially among those who want to have their food as 'natural' as possible. They may be contaminated with pathogens that cause gastrointestinal diseases. According to the Centers for Disease Control, those (cheeses) contaminated with Staph. enterotoxin have become a widespread problem. Salmonella also survives the raw cheese making process." (CONSUMERS RESEARCH MAGAZINE, Feb. 1984, p. 8)
"Health officials in Switzerland have linked numerous cases of Listeriosis between 1984 and 1987 with a soft cheese, Vacherin Mont d'Or; which included 31 deaths." In the U.S. in 1986, the FDA found Listeria contamination in 3% of 1000 dairy-product plants: they found 1% contamination in U.S. Erie, Camembert, Mozzarella, and Liederkranz. Only 2 of 75 samples of hard cheeses were found to be contaminated (not a very large sample). "The FDA became alarmed that significant numbers of foreign soft-cheese entries contained Listeria."
Listeria mainly affects pregnant women and their fetuses and newborns: it commonly causes still-births: and in newborns, causes septicemia, meningitis, and encephalitis with a mortality rate of 33%. It also causes serious often fatal illness in the elderly and those with low immunity, such as alcoholics and AIDS patients; and those on corticosteroids and cancer chemotherapy or those who have had organ transplants.
Listeria resists heat and salt treatment, and can grow at temperatures below 40° F, which means that it can grow in refrigeration. (FDA CONSUMER, July-August 1988, p. 12)
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