Transcript The Perils of Raw Milk Linda K. Gaul, PhD, MPH Epidemiologist, Infectious Disease Control Unit.

The Perils of Raw Milk
Linda K. Gaul, PhD, MPH
Epidemiologist, Infectious Disease Control Unit
History of Raw Milk
Consumption, Illnesses, and Regulation
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History of Pasteurization
and Milk-Associated Illnesses
• Pasteur worked on process to prevent wine spoilage
• Pasteurization is the heat treatment of food to kill bacteria
• Early 1900s, pasteurization used for milk
• Fewer milkborne infections were noted
• In the 1930s, milk pasteurization was mandated in many
large cities
• In 1938, milkborne outbreaks made up ~25% of
outbreaks due to contaminated food and water
Hall, C.W and Trout, GM. Milk Pasteurization; AVI Publishing Company; 1968.
LeJeune, J.T. and Rajala-Schultz, P.J. CID. 2009;48:93-100.
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Pathogens Historically Associated
With Raw Milk
• Campylobacter sp.
• Shiga-toxin producing Escherichia coli (STEC)
• Including E. coli O157:H7
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Salmonella sp.
Listeria monocytogenes
Staphylococcus aureus
Yersinia enterocolitica
Mycobacterium bovis - Bovine tuberculosis
Brucella melitensis
Dairy animals are reservoirs for these organisms
Today, M. bovis and B. melitensis are controlled by nationwide eradication
programs for cattle herds. Occasionally, infected cattle are still found.
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History of Pasteurization and MilkAssociated Illnesses, continued
• By 1950, pasteurization was standard for
commercial US milk supply
• Nearly all pasteurized milk today is heated to
161oF for 15 seconds
• In 2000, milkborne outbreaks made up <1%
of outbreaks due to contaminated food and
water
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Achievements in Public Health, 1900-1990
Safer and Healthier Foods
Morbidity and Mortality Week Report
October 15, 1999
“Once the sources and characteristics of foodborne
diseases were identified--long before vaccines or
antibiotics--they could be controlled by handwashing,
sanitation, refrigeration, pasteurization, and pesticide
application.”
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Regulation of Raw Milk Sales
• In 1987, FDA prohibited interstate sales of unpasteurized milk
• The FDA does not regulate intrastate sales
• Each state regulates intrastate unpasteurized milk sales
• States vary in the type of raw milk sales that are allowed, if any
• The sale of raw milk is illegal in 20 states
• 30 states allow the sale of raw milk in certain settings
• 13 allow retail store sales
• 14 allow on-farm sales only (including Texas)
• 2 states allow sales by prescription only
• 1 state allows sales through purchase of “cow shares”
• Licensing and requirements for raw milk sales vary by state,
where allowed
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Status of Raw Milk Sales, 2008
Centers for Disease Control and Prevention (CDC), October 2009
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Milk Consumption Preferences
2002-2003 FoodNet Survey
Milk consumption during the past 7 days:
Milk type
Any kind
Unpasteurized
Survey pop. Estimated US
drinking
pop. drinking (#)
81.6%
248,000,000
3.5%
8,680,000
Consumer 23 times more likely to drink pasteurized milk
Estimated US population 288 million in 2002-03
U.S. Census Bureau, http://www.census.gov/popest/estimates.html
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Epidemiology of Illnesses Associated
with Raw Milk Consumption
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How Illnesses are Associated
with Specific Foods
• Sporadic cases are only rarely linked to a
specific food vehicle
• Outbreak data provide the best evidence for
links to food vehicles
• Milkborne outbreaks have been associated
with:
• Unpasteurized milk and milk products
• Inadequately pasteurized or post-pasteurization
contaminated milk and milk products
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Milk-Associated Outbreaks,
Scotland, 1980-2004
# of Outbreaks
30
25
1983 Legislat ion Prohibit s
Sale of Raw Milk
20
1986 Legislat ion Prohibit s
15
10
payment t o f arm workers
1424
in raw milk
Cases
126
Out breaks f rom
Cases
1986-2004 limit ed

5

45
t o f arm f amilies
Cases
0
1980-1982
1983-1985
1986-1988
1989-2004
Sharp. J Med Micro. 1989. 29:239-242.; Food Standards Agency, 5/11/2009.
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Raw Milk Associated Outbreaks,
US, 1973-1992
• 46 outbreaks reported from 21 states
• 1733 cases
• 40 (86%) occurred in states where raw milk sale
was legal at time of outbreak
• 6 (14%) occurred in states where raw milk sale
was not legal at time of outbreak
• 6 times as many outbreaks in states where
raw milk sales were legal
Headrick, et al. 1998 AJPH.88:1219-1221
Raw Milk Associated Outbreaks,
US, 1998-2007
Number of Outbreaks
Raw Pasteurized**
Milk
Milk
51
12
Number of Cases
1054
2213
57
25
Number of Hospitalizations
**The pasteurized milk outbreaks were traced back to attempted pasteurization that failed
or contamination after pasteurization
• 41 (80%) occurred in states where raw milk sale was legal at time
of outbreak
• 10 (20%) occurred in states where raw milk sale was not legal at
time of outbreak
•4 times as many outbreaks in states where raw milk sales were
legal
Center for Disease Control and Prevention (CDC): October 2009
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Reported Outbreaks
Associated with Raw Milk 1998-2007
National Association of State Departments of Agriculture Raw Milk Survey April 2008; CDC, October 2009
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Pathogens in Raw Milk Associated
Outbreaks, US, 1998-2007
Number of Outbreaks
Outbreak Pathogens
Campylobacter Spp
Escherichia coli O157:H7
Listeria monocytogenes
Salmonella Spp
Unknown agent
Raw
Milk
51
Pasteurized**
Milk
12
42
7
0
2
0
3
0
1
3
5
**The pasteurized milk outbreaks were traced back to attempted pasteurization that failed or
contamination after pasteurization
Center for Disease Control and Prevention (CDC): October 2009
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Texas Outbreaks Associated with Raw Milk
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Texas Outbreaks Associated with Raw
Milk or Raw Milk Cheese*
• 2000 Campylobacteriosis outbreak
• 2 cases
• Sampled raw goat milk at a conference
• Included in 1998-2007 outbreak summary slide
• 2003-2009 Listeriosis outbreak
• 46 cases, 9 deaths
• 29 mother-baby sets (5 miscarriages, stillbirths, infant deaths)
• 17 immonocompromised persons (4 deaths)
• Case-patients consumed unpasteurized queso fresco (cow milk)
• Cheese produced in Mexico
• Cheese carried legally into US
• Cheese sold illegally in US
• NOT included in 1998-2007 summary slide
*Cheeses not included in other outbreak information
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Campylobacteriosis Outbreaks
Associated with Raw Milk,
Youth Activities, US, 1981-1990
• CDC survey of 50 states, Puerto Rico
• Youth activities: School field trips to dairy
farms, other
• 20 outbreaks, 11 states
• 1013 youths, adults drank raw milk, 458 ill
• Attack rate 45%
• 12 known hospitalizations, no deaths
• 70% of outbreaks with children K-3rd grade
• Only 60% of outbreaks reported to CDC
• Wood, et al. 1992. JAMA. 268:3228-3230.
Nutritional and Other Health Considerations,
Raw vs. Pasteurized Milk
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Claimed Advantages of
Unpasteurized Milk over Pasteurized
Milk: Are These Real?
• There are no scientific studies reported in peer-reviewed
literature that show any advantage of unpasteurized milk over
pasteurized
• Some raw milk advocates claim that certain beneficial
proteins and other chemicals are degraded substantially
during pasteurization
• Milk is not a significant source for some of these
chemicals, such as vitamin C
• Only ultra-high temperature pasteurization destroys
many other chemicals
• Unpasteurized milk always carries with it the risk of illness
caused by pathogens
• The nutrients for which milk is an important source are not
destroyed or altered by pasteurization
• Calcium, protein
Characteristics of Human Breast Milk
and Animal Milk
Human breast milk
Unpasteurized animal milk
• Mother produces antibodies,
other protective substances
against pathogens in her
environment
• Milk is sterile
• Animals produce antibodies,
other protective substances
against pathogens in their
environment
• Milk is not sterile,
•
Unless mother has an infection
Newman. 1995. SA:273:76-79; Potter, 1984. JAMA:252, 2048-2052
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Even if animals are healthy
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Characteristics of Human Breast Milk
and Animal Milk
Human breast milk
Unpasteurized animal milk
• Substances suppress
harmful bacteria and block
their absorption, promote
beneficial bacteria
• Benefits last only ~3 months,
when baby’s immune system
becomes more mature
• Substances may suppress
harmful bacteria and block
their absorption, promote
beneficial bacteria
• Any benefits would last only
~3 months, when baby’s
immune system becomes
more mature
Newman. 1995. SA:273:76-79; Potter, 1984. JAMA:252, 2048-2052
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American Academy Of Pediatrics
Position Statement
“Prevention of disease in children is one of the
Academy’s highest priorities. Raw milk is known to
transmit infectious diseases, and pasteurization is
known to minimize risk. Raw milk has no benefits that
would justify any increase in risk to children. The
Academy supports legislation efforts at both the state
and national levels that mandate pasteurization of all
dairy products.”
Bradley et. al. December 2008. AAP News. Volume 29
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Regulation of Raw Milk in Texas
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Current Raw Milk Regulations
In Texas
• Farms selling Grade “A” Raw for Retail Milk must be
licensed with DSHS
• However, DSHS is aware of some unlicensed farms
• The consumer can purchase raw milk from a farm that
has a Grade “A” Raw for Retail permit
• Grade “A” Raw for Retail dairies have same requirements
as the dairies that sell milk to be pasteurized, except
• Additional requirements for coliform and pathogen
testing
• Milk must be stored at or below 45 ºF until sold
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Licensed Retail Raw Milk Farms
35 Licensed Grade “A”
Raw for Retail Dairies
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“Consumption of raw milk remains a preventable
cause of foodborne disease outbreaks.”
Headrick, et al. 1998 AJPH.88:1219-1221
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Acknowledgements
Julie Loera, Division of Regulatory Affairs, DSHS
Frank Borden, Division of Regulatory Affairs, DSHS
Gene Wright, Division of Regulatory Affairs, DSHS
Maricela Montoya, WIC Clinical Services, DSHS
Tracy Hayward, Division of Prevention and Preparedness, DSHS
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