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The Raw Milk Beat Goes On: A Look at the Literature and the 60-Day Raw Milk Cheese Aging Rule – Part 3

Regulation of Raw Milk Cheeses in Other Countries

Canada regulates cheeses made from raw milk similar to the US, except for Quebec where raw milk cheeses can be manufactured without 60-day aging if strict rules for milk quality and veterinary inspections of cattle herds are followed.  In 1996, following an outbreak of E. coli O157:H7 linked to cured Gouda cheese, Health Canada proposed a ban on all raw milk cheeses, but the initiative was defeated by industry and consumer groups (Honish 2005).

The European Union has no aging rule, but their requirements for hygiene during milking, storing, and collection of milk for cheesemaking are likely much stricter than in the US.  Additionally, requirements for both animal health and worker/personnel health help ensure safe raw milk cheese production.  Cheeses made from raw milk in Europe must be labeled “Made with Raw Milk.”

The regulation of raw milk cheeses in Australia and New Zealand has been an area of intense controversy in recent years.  Australia bans all domestic raw milk cheeses, but allows importation of certain cheeses—Roquefort, Gruyere, Sbrinz, Emmental—from Europe and Switzerland provided they are aged 90 days and meeting European safety standards (Standard 4.2.4A).  Domestic cheeses must be “thermised” by using a low temperature heat treatment followed by aging for 90-days.

Epidemiology

The epidemiology of cheese-related outbreaks has changed in the US since the 60-day aging rule was established in 1950.  The studies conducted in the 1940’s that presumably  provided the basis for the rule were based on diseases such as Typoid fever, an infection transmitted by human carriers.  Today, most of the cheese-linked illnesses are due to zoonotic enteric pathogens carried by ruminants including Campylobacter, E. coli O157:H7, Listeria monocytogenes, and SalmonellaL. monocytogenes is also a ubiquitous inhabitant of the dairy environment.  Table 2 shows some of the major pathogens that may survive in cheese even after aging.  

Internationally, dairy-related outbreaks are relatively uncommon in developed countries, but an estimated 11.8% are attributed to cheeses made from raw milk (FSANZ 2006).  Foodborne disease outbreaks have been reported in all countries that allow raw milk cheese including France where raw milk cheeses are popular (Desenclos 1996; Desenclos 1996; DeValk 2000; Dominguez 2009; Haeghebaert 2003; Ostyn 2010).  The most recent published review in the US examined reported cheese-related outbreaks and illnesses from 1973 – 1992 (Altekruse 1998).  Fresh Mexican-style cheeses (for example, queso fresco) were the most frequently implicated vehicle and caused 56 of the 58 deaths described in the review; the other 2 deaths were linked to improper pasteurization of Mozzarella cheese. 

Table 2.  Bacterial pathogens that can survive in cheeses aged for 60 days.

Organism

Incubation

Duration of illness

Signs and symptoms

Comment

Brucella spp.

1-2 months or longer

May relapse for years

Fever, headache, joint pain, depression, weight loss

Cause of abortions in dairy animals

Campylobacter

2-5 days

2-7 days; some patients develop paralytic syndrome as a long-term complication

Diarrhea (sometimes bloody), cramps, fever, nausea, vomiting, muscle aches

Found in health dairy animals

E. coli O157 and other pathogenic E. coli

2-8 days

5-8 days; some patients develop kidney disease or other long-term complications

Diarrhea (often bloody), cramps, sometimes low-grade fever

Found in healthy dairy animals

Listeria monocytogenes

3 – 70 days (average 3 weeks)

Variable depending on susceptibility; Death rate in patients with meningitis as high as 80%; septicemia as high as 50%

Septicemia, meningitis, intra-uterine infections in pregnant women with spontaneous abortions and stillbirths

Found in healthy dairy animals and the dairy processing environment

Mycobacterium bovis

4 – 12 weeks to positive tuberculin test; 1-2 years for systemic infection

Years; may persist lifetime as latent infection

Pulmonary and extra-pulmonary disease

Systemic illness in cattle; transmitted through milk and aerosols

Salmonella enterica

6 – 48 hours

 2-8 days; some patients develop long-term complications including arthritic disease

Diarrhea, nausea, vomiting, cramps fever

Some strains cause illness in dairy animals

Salmonella typhi

8 – 14 days

Variable;  case fatality of 10-20% without antibiotic treatment

Fever, cramps, diarrhea, anorexia

Human carriers

Staphylococcus enterotoxin

2-4 hours

1-3 days

Vomiting, nausea, cramping

Animal and human carriers; toxin produced following growth in a food

The problem with fresh, soft cheeses is ongoing and most often associated with use of inadequately pasteurized milk and cross-contamination in the processing environment (CDC 2000; CDC 2001; CDC 2008; CDC 2009; Cody 1999; MacDonald 2005; Villar 1999).  Listeria monocytogenes and Salmonella are pathogens most often found in fresh Mexican-style soft cheeses as reviewed previously (Marler, 2009).  Over the last decade, there have been only two deaths from cheese made with raw milk; both occurred in 2003, and were due to consumption of contaminated fresh (un-aged) queso fresco Mexican-style cheese (CDC OutbreakNet).

In contrast, outbreaks and illnesses linked to 60-day aged cheese are relatively rare despite microbiological evidence of pathogen survival in these cheeses (Altekruse 1998; D’Amico 2008b; D’Amico 2010; Donnelly 1990; Jaros 2008; Reitsma 12996; Schlesser 2006).  Researchers from the University of Vermont have speculated that the relative paucity of outbreaks and illnesses associated with 60-day aged cheese may be due to 1) a low contamination level in milk used for cheesemaking or 2) alterations in virulence of pathogens within the cheese matrix (D’Amico 2010).

However, there are notable exceptions including E. coli O157:H7 outbreaks linked to cured Gouda cheese in Canada in 2002 (Honish 2005) and the US in 2010 (CDC 2010).  In the latter, at least 38 cases have been linked to consumption of Gouda cheese made with raw milk and presumably aged for 60-days in accordance with FDA regulations.  The CDC summarized findings from the ongoing investigation in a November 24, 2010 report: http://www.cdc.gov/ecoli/2010/cheese0157/index.html

References

1.              Altekruse, S. F., B. B. Timbo, J. C. Mowbray, N. H. Bean, and M. E. Potter. 1998. Cheese-associated outbreaks of human illness in the United States, 1973 to 1992: sanitary manufacturing practices protect consumers. J Food Prot 61:1405-7.

2.              Bachmann, H. P., and U. Spahr. 1995. The fate of potentially pathogenic bacteria in Swiss hard and semihard cheeses made from raw milk. J Dairy Sci 78:476-83.

3.              Back, J. P., S. A. Langford, and R. G. Kroll. 1993. Growth of Listeria monocytogenes in Camembert and other soft cheeses at refrigeration temperatures. J Dairy Res 60:421-9.

4.              CDC. 2000. Outbreak of Escherichia coli O157:H7 infection associated with eating fresh cheese curds–Wisconsin, June 1998. MMWR Morb Mortal Wkly Rep 49:911-3.

5.              CDC. 2001. From the Centers for Disease Control and Prevention. Outbreak of Listeriosis associated with homemade Mexican-style cheese–North Carolina, October 2000-January 2001. JAMA 286:664-5.

6.              CDC. 2008. Outbreak of multidrug-resistant Salmonella enterica serotype Newport infections associated with consumption of unpasteurized Mexican-style aged cheese–Illinois, March 2006-April 2007. MMWR Morb Mortal Wkly Rep 57:432-5.

7.              CDC.  2009.  Campylobacter jejuni Infection Associated with Unpasteurized Milk and Cheese — Kansas, 2007. MMWR Morb Mortal Wkly Rep 57:1377-1379.

8.              CDC.  OutbreakNet.  Foodborne Outbreak Online Database.  Available from:  http://www.cdc.gov/foodborneoutbreaks/Default.aspx

9.              CDC.  2010.  Investigation Update: Multistate Outbreak of E. coli O157:H7 Infections Associated with Cheese.  Available from:  http://www.cdc.gov/ecoli/2010/cheese0157/index.html

10.          Cody, S. H., S. L. Abbott, A. Marfin, B. Schulz, P. Wagner, K. Robbins, J. C. Mohle-Boetani, and D. J. Vugia. 1999. Two outbreaks of multidrug-resistant Salmonella serotype typhimurium DT104 infections linked to raw-milk cheese in Northern California. JAMA 281:1805-10.

11.          D’Amico, D. 2008a. Incidence, ecology, and fate of target foodborne pathogens in the cheesemaking continuum. University of Vermon.  Available from:  http://library.uvm.edu/jspui/bitstream/123456789/165/1/damicofinal.pdf

12.          D’Amico, D. J., M. J. Druart, and C. W. Donnelly. 2008b. 60-day aging requirement does not ensure safety of surface-mold-ripened soft cheeses manufactured from raw or pasteurized milk when Listeria monocytogenes is introduced as a postprocessing contaminant. J Food Prot 71:1563-71.

13.          D’Amico, D. J., E. Groves, and C. W. Donnelly. 2008c. Low incidence of foodborne pathogens of concern in raw milk utilized for farmstead cheese production. J Food Prot 71:1580-9.

14.          D’Amico, D. J., and C. W. Donnelly. 2010a. Microbiological quality of raw milk used for small-scale artisan cheese production in Vermont: effect of farm characteristics and practices. J Dairy Sci 93:134-47.

15.          D’Amico, D. J., M. J. Druart, and C. W. Donnelly. 2010b. Behavior of Escherichia coli O157:H7 during the manufacture and aging of gouda and stirred-curd cheddar cheeses manufactured from raw milk. J Food Prot 73:2217-2224.

16.          Deschenes, G., C. Casenave, F. Grimont, J. C. Desenclos, S. Benoit, M. Collin, S. Baron, P. Mariani, P. A. Grimont, and H. Nivet. 1996. Cluster of cases of haemolytic uraemic syndrome due to unpasteurised cheese. Pediatr Nephrol 10:203-5.

17.          Desenclos, J. C., P. Bouvet, E. Benz-Lemoine, F. Grimont, H. Desqueyroux, I. Rebiere, and P. A. Grimont. 1996. Large outbreak of Salmonella enterica serotype paratyphi B infection caused by a goats’ milk cheese, France, 1993: a case finding and epidemiological study. BMJ 312:91-4.

18.          De Valk, H., E. Delarocque-Astagneau, G. Colomb, S. Ple, E. Godard, V. Vaillant, S. Haeghebaert, P. H. Bouvet, F. Grimont, P. Grimont, and J. C. Desenclos. 2000. A community–wide outbreak of Salmonella enterica serotype Typhimurium infection associated with eating a raw milk soft cheese in France. Epidemiol Infect 124:1-7.

19.          Dominguez, M., N. Jourdan-Da Silva, V. Vaillant, N. Pihier, C. Kermin, F. X. Weill, G. Delmas, A. Kerouanton, A. Brisabois, and H. de Valk. 2009. Outbreak of Salmonella enterica serotype Montevideo infections in France linked to consumption of cheese made from raw milk. Foodborne Pathog Dis 6:121-8.

20.          Donnelly, C. W. 1990. Concerns of microbial pathogens in association with dairy foods. J Dairy Sci 73:1656-61.

21.          FDA.  21 C.F.R. Part 133–Cheeses and Related Cheese Products.  Available from:  http://law.justia.com/us/cfr/title21/21cfr133_main_02.html

22.          FDA.  21 C.F.R. Part 1240.61–Mandatory pasteurization for all milk and milk products in final package form intended for direct human consumption.  Available from:  http://law.justia.com/us/cfr/title21/21-8.0.1.5.48.4.1.2.html

23.          FSANZ.  2006.  A risk profile of dairy products in Australia.  Available from:  http://www.foodstandards.gov.au/_srcfiles/P296%20Dairy%20PPPS%20FAR%20Attach%202%20FINAL%20-%20mr.pdf

24.          Govaris, A., D. K. Papageorgiou, and K. Papatheodorou. 2002. Behavior of Escherichia coli O157:H7 during the manufacture and ripening of feta and telemes cheeses. J Food Prot 65:609-15.

25.          Haeghebaert, S., P. Sulem, L. Deroudille, E. Vanneroy-Adenot, O. Bagnis, P. Bouvet, F. Grimont, A. Brisabois, F. Le Querrec, C. Hervy, E. Espie, H. de Valk, and V. Vaillant. 2003. Two outbreaks of Salmonella enteritidis phage type 8 linked to the consumption of Cantal cheese made with raw milk, France, 2001. Euro Surveill 8:151-6.

26.          Headrick, M. L., S. Korangy, N. H. Bean, F. J. Angulo, S. F. Altekruse, M. E. Potter, and K. C. Klontz. 1998. The epidemiology of raw milk-associated foodborne disease outbreaks reported in the United States, 1973 through 1992. Am J Public Health 88:1219-21.

27.          Honish, L., G. Predy, N. Hislop, L. Chui, K. Kowalewska-Grochowska, L. Trottier, C. Kreplin, and I. Zazulak. 2005. An outbreak of E. coli O157:H7 hemorrhagic colitis associated with unpasteurized gouda cheese. Can J Public Health 96:182-4.

28.          Jaros, P., N. Cogger and N. French.  2008. A systematic review of the human disease evidence associated with the consumption of raw milk and raw milk cheeses.  A report prepared for the New Zealand Food Safety Authority (NZFSA).  Availabel from:  http://www.nzfsa.govt.nz/science/research-projects/final-report-rawmilk.pdf

29.          Johnson, M.E.  2002.  Cheese products.  In:  Applied Dairy Microbiology, 2nd Ed., Marth, E. H. and J.L. Steele (eds), Ch. 11, p.345-384.

30.          MacDonald, P. D., R. E. Whitwam, J. D. Boggs, J. N. MacCormack, K. L. Anderson, J. W. Reardon, J. R. Saah, L. M. Graves, S. B. Hunter, and J. Sobel. 2005. Outbreak of listeriosis among Mexican immigrants as a result of consumption of illicitly produced Mexican-style cheese. Clin Infect Dis 40:677-82.

31.          Marler, W.  2009.  Comparing the food safety record of pasteurized and raw milk products – Part 3.  Available from:  http://www.marlerblog.com/lawyer-oped/comparing-the-food-safety-record-of-pasteurized-and-raw-milk-products—part-3/.

32.          Marth, E. H. 1969. Salmonellae and salmonellosis associated with milk and milk products. A review. J Dairy Sci 52:283-315.

33.          Oliver, S. P., K. I., Boor, S. C. Murphy, and S.e E. Murinda.  2009.  Food safety hazards associated with consumption of raw milk.  Foodborne Pathog Dis. 6:793-806.

34.          Ostyn, A., M. L. De Buyser, F. Guillier, J. Groult, B. Felix, S. Salah, G. Delmas, and J. A. Hennekinne. 2010. First evidence of a food poisoning outbreak due to staphylococcal enterotoxin type E, France, 2009. Euro Surveill 15.

35.          Reitsma, C. and D. H. Henning.  1996. Survival of enterohemmorrhagic Escherichia coli O157:H7 during the manufacture and curing of cheddar cheese. J Food Prot 59:460-464.

36.          Schlesser, J. E., R. Gerdes, S. Ravishankar, K. Madsen, J. Mowbray, and A. Y. Teo. 2006. Survival of a five-strain cocktail of Escherichia coli O157:H7 during the 60-day aging period of cheddar cheese made from unpasteurized milk. J Food Prot 69:990-8.

37.          Sheehan, J., R. Childers, and S. Clanci.  2004.  Ask the regulators:  enhancing the safety of dairy and other animal based foods.  Available from:  http://www.foodsafetymagazine.com/article.asp?id=1354&sub=sub1

38.          Villar, R. G., M. D. Macek, S. Simons, P. S. Hayes, M. J. Goldoft, J. H. Lewis, L. L. Rowan, D. Hursh, M. Patnode, and P. S. Mead. 1999. Investigation of multidrug-resistant Salmonella serotype typhimurium DT104 infections linked to raw-milk cheese in Washington State. Jama 281:1811-6.

39.          Werner, S. B., G. L. Humphrey, and I. Kamei. 1979. Association between raw milk and human Salmonella dublin infection. Br Med J 2:238-41.

  • Anne

    Sounds like driving a car is WAYYY more dangerous than eating a steady diet of raw milk products. Why do we need to be protected by the state?

  • Curious George

    Sounds like driving a car is WAYYY more dangerous than E. coli in cookie dough, burgers, or spinach; or salmonella in peanut butter or eggs. Why do you think we need to be protected by the state?
    Oh, and by the way, the state does regulate and impose restrictions on driving to protect the public. Have you heard of speed limits, stop lights, driver’s licenses, DUI and seatbelt laws, and even requirements for emissions testing?

  • Debra C

    Typhoid fever was more than likely from drinking water. Back in the 1940′s the majority of people had only well water., as a matter of fact most drinking water has some type of bacteria and most Medical Doctors will say that we all carry some form of bacteria in our system, , e coli, salmonella, H Pylori and so on,, it is when our immune system goes out of whack that we develop the symptoms and an out break occurs..