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


Slide3: Milk Quality 00 49 99 00 29 49 69 89 99 Pasteurization of milk Milkborne diseases 1000 500 250


Slide4: 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 ?


Improved farm hygiene and milking practicesImproved milk handling and processing technologyEducated consumers and higher consumer awareness on food safety Still………………. : Improved farm hygiene and milking practices Improved milk handling and processing technology Educated consumers and higher consumer awareness on food safety Still……………….


Newspapers inform public about outbreaks!: 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


Why do milkborne illnesses occur ?: Why do milkborne illnesses occur ? Faulty pasteurization of fluid milk Defective pasteurizer -- less likely Post-pasteurization contamination of 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


Slide8: 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% How prevalent is consumption of raw milk ?


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]: 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


Slide10: 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.


How do pathogens get into raw milk ?: How do pathogens get into raw milk ?


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


Slide13: Other routes of entry


Slide14: Putting it all together !


Salmonella : 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


Salmonella Typhimurium DT 104: 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


Campylobacter jejuni: 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


Escherichia coli: 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


Yersinia enterocolitica: 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 1978 22% Ontario Canada 1978 18% Ontario Canada 1981 81% France 1984 37% Italy 1992 15.1% USA 1997 6.1% USA…. Natural hosts


Listeria monocytogenes: 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


Why do people consume raw milk ?: 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


Slide22: 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)