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Appendix F Raw Milk An Editorial RAW MILK: A CONTINUING VEHICL~FOR THE TRANSMISSION OF INFECTIOUS DISEASE AGENTS IN THE UNITED STATES* To many infectious disease workers it appears incredible that in this day and age there should be a controversy over whether raw milk can serve as a vehicle of transmission for Salmonella and other human path- ogens. However, the controversy is a very real one and has been present, albeit with different degrees of intensity, in various parts of the United States since the turn of the century. Human milk is the most valuable single food for infants, and in its absence cow's milk is a good substitute. However, the shockingly poor level of sanitation in many commercial dairies during the latter part of the 19th century resulted in devastating outbreaks of infectious diseases; many infants and children died because of contaminated milk. An im- portant initial response to these deplorable conditions in commercial dairies was the formulation, in 1893, of Medical Milk Commissions which es- tablished sanitary criteria for the maintenance of dairy herds and for the collection and handling of market milk. These criteria included standards for raw milk which was "certified" by the Commissions; such raw milk exists today under the copyrighted trademark "Certified Milk." The work of the Medical Milk Commissions was a positive step in * This editorial is reprinted with permission from the Journal of Infectious Diseases 146(3):440- 441, 1982. Published by The University of Chicago Press. Copyright ~ 1982 by The University of Chicago. 395
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396 APPENDIX F reducing contamination of commercial raw milk, but it was recognized by medical authorities that milk certification could not eliminate contam- ination. The underside of a cow is often caked with mud and manure so that, even if it is washed and wiped with several towels, the udders can hardly be considered clean enough (much less sterile) to collect milk for direct human consumption. Pasteurization provided a means to prevent milk from transmitting in- fectious disease agents. In 1893, Nathan Straus, a layman who personally led the fight to have all milk in the United States pasteurized, established the first facility for the pasteurization of milk for infant feeding in New York City.2 A battle between advocates of raw milk and pasteurized milk has raged since then. Infectious disease epidemiologists have amply documented the health risks of raw milk (including certified raw milk); the raw milk industry has stressed the benefits of raw milk and minimized or denied any infec- tious disease hazards. Raw milk advocates perceive health benefits from the alleged "essential" enzymes, vitamins, and other undefined beneficial substances which they claim are destroyed by pasteurization. They also claim that pasteurization of the proteins in milk, together with homoge- nization, promote atherosclerosis. What has evolved is a virtual cult of advocacy for raw milk in which some believers absolutely deny any pos- sible transmission of infectious disease agents by this so-called life-giving fluid. Other raw milk advocates concede possible "minuscule" contam- ination of raw milk on occasions with enteric pathogens such as Salmonella but cite older medical papers which state that huge doses of Salmonella (~106 organisms) are necessary to cause human disease. Those who place such confidence in the safety of milk contaminated with Salmonella ignore the potential logarithmic growth of these bacteria in milk: an initially low level of contamination may, under suitable conditions, become very high in a few hours. Such misplaced confidence also ignores recent findings that contamination as low as one Salmonella organism/lOOg of food has resulted in human infection and diseased The raw milk industry believes that the abundant laboratory and epi- demiologic data which associate raw milk with disease are, at best, con- trived. Its concept of a milkborne outbreak is one in which virtually 100% of exposed persons develop severe illness. Raw milk advocates find in- comprehensible those factors known to govern the transmission of infec- tion by contaminated raw milk as well as those variables which significantly reduce the number of disease cases which come to public health recog- nition. These factors can be placed in several major groups. Initially, there are varying levels of infection at the source. Cows suffer from enteric and mammary infections, and contamination of milk is a
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APPENDIX F 397 possibility at all times. After milking, variations in holding conditions and holding temperatures up to the time of consumption can lead to rapid growth of organisms. Equally important in determining whether disease may occur is the response of persons who consume contaminated raw milk. There are differences in the number of organisms ingested; host defenses, such as gastric acidity; transit time; and immune status. Finally, signs and symptoms of disease may vary widely as do patients in seeking medical care of physicians in determining medical diagnoses. Laboratory tests may or may not have been obtained for a given patient, and labo- ratories differ in their isolation and identification of pathogens. Ultimately, great variation exists in reporting and investigation of disease. Public health epidemiologists are convinced that many thousands of enteric in- fections due to raw milk contaminated with Salmonella, Campylobacter, and other enteric pathogens occur annually in the United States, but few of these infections are recognized or associated with raw milk. The consistency of the findings of the Centers for Disease Control reported in this issue of the Journal4 with previously published results in Californias will likely be viewed by the unbelieving raw milk industry as further evidence of what is alleged to be a conspiracy among public health agencies to deny raw milk to those who want and need the "elixir of life" the industry sells. The report by Taylor et al.4 does not present any new or startling findings and may be considered to be essentially preaching to the already converted. Infectious disease professionals consider the sci- entific case against raw milk to be irrefutable. Several national health organizations including the American Academy of Pediatrics, the Con- ference of State and Territorial Epidemiologists, the American Veterinary Medical Association, the U.S. Animal Health Association, and the Na- tional Association of State Public Health Veterinarians have adopted policy statements which recommend that milk and milk products for human consumption be pasteurized. In some 20 states where the sale of raw milk is legal, the American Veterinary Medical Association has recommended that raw milk carry a warning label: "Not pasteurized and may contain organisms that cause human disease." Even with such a label, any batch of raw milk confirmed to be contaminated with Salmonella or other human pathogens must be promptly removed from commercial distribution and home refrigerators. To do any less would be to condone continuation of human exposure to known pathogens. The raw milk industry has lost its suit in the scientific and medical courts, so it has now carried its case to the political and legal arenas, where it is a formidable opponent in what amounts to a court of last resort.6 In these forums, the industry and its advocates cannot be lightly dismissed, especially in the current climate of heightened concern for
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398 APPENDIX F personal liberties, freedom of choice, and frequent rejection of science. Infectious disease workers cannot rest on the accumulated scientific evi- dence alone since in the words of a modern epidemiologic sage "public policy is established by the public, not by scientists."7 It is the respon- sibility of all health professionals to see that the public-and the policy makers are adequately informed about the scientific findings so that public policy on raw milk may be compatible with scientific knowledge and protective of the public's health. James Chin Infectious Disease Section California Department of Health Services Berkeley, California REFERENCES 1. Methods and standards for the production of certified milk. American Association of Medical Milk Commissions. Alpharetta, Georgia, 1976, 46 pp. 2. Straus, L. G. Disease in milk: the remedy pasteurization. The life work of Nathan Straus, 2nd ed. (Reprint ed. Arno Press, New York, 1977). E. P. Dutton, New York, 1917, 383 pp. 3. Fontaine, R. E. Cohen, M. L., Martin, W. T., Vernon, T. M. Epidemic salmonellosis from cheddar cheese: surveillance and prevention. Am. J. Epidemiol. 111 :247-253, 1980. 4. Taylor, D. N., Bled, J. M., Munro, J. S. Feldman, R. A. Salmonella dublin infections in the United States, 1979-1980. J. Infect. Dis. 146:322-327, 1982. 5. Werner, S. B., Humphrey, G. L., Kamei, I. Association between raw milk and human Salmonella dublin infector. Br. Med. J. 2:238-241, 1979. 6. Currier, R. W. Raw milk and human gastrointestinal disease: problems resulting from legalized sale of "certified raw milk." Journal of Public Health Policy 2:226-234, 1981. 7. Stallones, R. A. Epidemiology and public policy: pro- and anti-biotic. Am. J. Epidemiol. 115:485-491, 1982.