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Microbial Pathogens in Raw Milk

Microbial Pathogens in Raw Milk. Bhushan Jayarao Extension Veterinarian Department of Veterinary Science The Pennsylvania State University University Park. Introduction. Milk and other dairy products are of superior quality and safety. Milk Quality. 00 29 49 69 89 99.

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Microbial Pathogens in Raw Milk

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  1. Microbial Pathogens in Raw Milk Bhushan Jayarao Extension Veterinarian Department of Veterinary Science The Pennsylvania State University University Park

  2. Introduction • Milk and other dairy products are of superior quality and safety Milk Quality 00 29 49 69 89 99

  3. Milkborne diseases 1000 500 250 Pasteurization of milk Milk Quality 00 29 49 69 89 99 00 49 99

  4. Historical perspective • 1900 -1940s: Tuberculosis, Bang’s disease, Diptheria, Typhoid fever highly prevalent • 1930s: Pasteurization of milk • 1940-1960s: Eradication of animal diseases (Brucellosis, Tuberculosis) • 1970s: Few human cases reported • 1990s:Few human cases still reported Why ?

  5. Improved farm hygiene and milking practicesImproved milk handling and processing technologyEducated consumers and higher consumer awareness on food safetyStill……………….

  6. Newspapers inform public about outbreaks! Milk makes kids sick ……… Salmonella outbreak traced to DAIRY farm …….. Milk contains bugs that makes people sick ………. Scientists say …….. Dairy farming ...... Dairy cows ….. All infected with dangerous bugs Killer bug on the loose …… dairy cows responsible

  7. Why do milkborne illnesses occur ? • Faulty pasteurization of fluid milk • Defective pasteurizer -- less likely • Post-pasteurization contaminationof milk and milk products • -- likely • Raw milk consumption • Rural communities with access to raw milk • Holistic / new age / back to nature - city folks ? • Visitors on farms • raw milk products

  8. How prevalent is consumption of raw milk ? • Highly prevalent in the rural communities • Rohrbach & others: 1991, Eastern Tennessee - 34.9% • Jayarao & others: 1997, South Dakota & Minn.- 60% • Jayarao & others: 1998, Pennsylvania - 54%

  9. The Epidemiology of Raw Milk - Associated Foodborne Disease Reported in the United States 1973-1992 [ Headrick and others, Am. J. Pub. Hlth. 88, 1219-1221; 1998] • Results of the study • 46 raw milk associated outbreaks reported were during the study period • 40 outbreaks (87%) occurred in states where the intrastate sale of raw milk was legal • Conclusions of the study • Consumption of raw milk remains a preventable cause of foodborne disease outbreaks Legal to sell raw milk WA, CA, OR, MO, ID, NV, AR, NM,TX, UT, SD, NE, KS, OK, MN, MO, AR, OH, PA, NY, ME, VT, NH, CONN, MA SC,IL, RI, WI Illegal to sell raw milk ND, WY, CO, IA, MI, IN, KY, TN, LA, AL, GA, FL, NC, AL, PR, WV, VA, MD, NJ, HA, DE, MD

  10. Health risks associated with raw milk ? • Several reports on foodborne outbreaks due to consumption of raw milk • Escherichia coli O157:H7 • Salmonella typhimurium DT104 • Campylobacter jejuni • Listeria monocytogenes • Yersinia entercolitica • Salmonella spp.

  11. How do pathogensget into raw milk ?

  12. How do Pathogens gain access to a farm ? Most important sources of infection Replacement calves trucks heifer/ cows birds /pests feed water visitors

  13. Other routes of entry

  14. Putting it all together !

  15. Salmonella • Occur in humans, warm and cold blooded animals, food and environment • Pathogenic to humans and many animals • Causes typhoid, enteric fevers, gasteroenteritis and septicaemia • More than 2200 types of Salmonella • Prevalence in bulk tank milk • 1987 4.7%* USA • 1988 0.2% United Kingdom • 1988 2.9% Canada • 1992 0.16% Ireland • 1992 8.9% USA • 1995 0.36% England & Wales • 1997 6.1% USA ……... • 1998 0.17% Canada Light Microscope Electron Microscope

  16. Salmonella Typhimurium DT 104 • Emerging foodborne pathogen • Detected in several countries • Why is DT 104 of concern ? • Multiple antibiotic resistance • Ampicillin • Chloramphenicol • Streptomycin • Sulfonamides • Tetracycline • DT 104 has been isolated from; • poultry, swine, cattle and wild animals, and from bulk tank milk

  17. Campylobacter jejuni • Inhabitant in the reproductive tract, intestine, and oral cavity to humans and animals • Excreted in large numbers in feces • 1983- Campylobacterosis associated with raw milk consumption in PA • Prevalence in bulk tank milk • 1982 0.9% USA • 1983 1.5% USA • 1986 4.8% USA • 1988 5% Netherlands • 1988 6% UK • 1988 4% USA • 1992 12.3% USA • 1997 9.2% USA ……... • 1998 0.47% Canada

  18. Escherichia coli • Occur as normal flora in the lower part of intestine of warm blooded animals • Toxin producing strains of E. coli are important agents of food-borne illnesses • Emerging pathogen E. coli O157:H7; dairy cattle considered as reservoirs. • Prevalence of enterotoxigenic E. coli in bulk tank milk • 1989 1.4% Canada • 1997 3.9% Germany • 1997 12.3 % Canada • 1997 3.8% USA ……... • 1998 0.87% Canada

  19. Yersinia enterocolitica • Occur in a broad spectrum of habitats including man, animals, rodents, birds, soil, water, dairy products and other foods. • Yersinia enterocolitica causes chronic diarrhea and severe septicaemia • Prevalence of Y. entercolitica in BTM Natural hosts • 1978 22% Ontario Canada • 1978 18% Ontario Canada • 1981 81% France • 1984 37% Italy • 1992 15.1% USA • 1997 6.1% USA….

  20. Listeria monocytogenes • Widely distributed in the environment • Listeria monocytogenes pathgoenic to humans and animals • Several reported outbreaks following consumption of raw milk • Prevalence of L. monocytogenes in bulk tank milk • 1987 4.2% USA • 1988 1.3% Canada • 1988 5.4% Canada • 1990 5.2% South Africa • 1992 4.9% Ireland • 1992 4.1% USA • 1995 5.1% England and Wales • 1997 4.6% USA... • 1998 2.7% Canada

  21. Why do people consume raw milk ? • Access to raw milk • Less access to pasteurized milk • Drinking raw milk practiced over time • A notion that raw milk is better than pasteurized milk

  22. Should one discontinue drinking raw milk ? • Yes ! If you are, • Concerned about pathogens in raw milk such as Salmonella DT 104 or E. coli O157:H7 • Elderly / young / immunocompromised/ expectant mothers • Genetic type HLA-27, which makes you more disposed to reactive arthritis if exposed to foodborne pathogens such as Campylobacter jejuni • Guilliame Barre’s syndrome • Concerned about long term effects on health • Can we pasteurize milk in our home ? • Yes ! you can, • Nasco- Safeguard Home Pasteurizer ( ~ $ 200)

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