Epidemiology of Foodborne Illnesses Linked to Consumption of Unpasteurized Dairy in the United State

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Epidemiology of Food-borne Illnesses Linked to
Consumption of Unpasteurized Dairy in the United
States, 1993-2007

• Jananne OConnell, DVM, MVPH
• North Carolina State University
• College of Veterinary Medicine

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History and Background

• The problem of food-borne illness linked to
  drinking unpasteurized milk was addressed by
  Marcia Headrick, DVM et al
• This paper looked at both the epidemiology of raw
  dairy-associated food-borne illness and the laws
  governing the sale of unpasteurized dairy from
  state to state.

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History and Background

• Regulations concerning the sale, or prohibition
  thereof, of milk or dairy products that have not
  been pasteurized are made on a statewide basis

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History and Background

• This paper showed an association between legal
  status of raw milk sales and raw dairy-associated
  outbreaks in different states during the study
  period of 1973-1992.
• QUESTION Does this association still hold?

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Methods

• Foodborne Illness Outbreak Surveillance
• Most outbreaks are detected, investigated, and
  controlled by local and state health departments
• CDC has a web-based reporting system that
  collects epidemiological information (electronic
  Foodborne Outbreak Reporting System, or eFORS)
• Approximately 1300 reports annually
• Data collected includes number ill, number
  hospitalized, number of deaths, etiology, and
  implicated food

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Methods

• Reviewed outbreaks reported through eFORS
• Outbreak defined as illness of two or more people
  following the ingestion of a common food
• Unpasteurized dairy outbreaks are defined as
• Liquid unpasteurized milk
• Unpasteurized cheese product

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Methods

• Multi-step process used to determine the legal
  status of the sale of raw milk in each state
• Surveys taken by the Dairy Division of the
  National Association of the State Departments of
  Agriculture (NASDA) in November 2004 and the
  Division of Animal Food Industry Services,
  Office of Dairy and Foods (Virginia Department of
  Agriculture), March 2005

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Methods

• Forty-six of fifty states gave consistent answers
  to the relevant questions in both surveys for 92
  agreement. State Public Health Veterinarians
  were contacted for clarification in the four
  states whose answers were inconsistent.

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Methods

• Developed a system to classify each state for
  each year of the survey into one of 4 categories
• Phone and email interviews with appropriate state
  governing body to verify findings from surveys
  and to confirm status of raw milk sales in the
  year 2006
• Data from 2007 provided courtesy of Adam Langer,
  DVM, MPH, DACPVM, Preventative Medicine Fellow in
  Foodborne Diarrheal Diseases Branch, Centers
  for Disease Control and Prevention

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Methods

• 1 Sale of raw milk is illegal, including animal
  shares
• 2 Sale of raw milk is illegal no restrictions
  on animal shares
• 3 Sale of raw milk is legal on farm only
• 4 Sale of raw milk is legal on farm and at
  retail

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2007 Additional Data

• Total outbreaks 1993 2007 n 80
• Liquid milk outbreaks n65
• Unpasteurized cheese outbreaks n 27

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Pathogens (Pasteurized/Probable Pasteurized)

• Bacillus ceres, Calicivirus/Norovirus,
  Campylobacter jejuni/ spp., Hepatitis A, Listeria
  monocytogenes, Salmonella enteriditis, newport,
  tennessee, typhimurium. Shigella sonnei,
  Staph. aureus toxin
• Strictly human pathogen high likelihood of
  post-pasteurization contamination

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Pathogens(Unpasteurized/Probable Unpasteurized)

• Brucella, Campylobacter jejuni/ spp., E. coli
  O157H7, L. monocytogenes, Salmonella
  bovismorbificans, enteriditis, java, newport,
  typhimurium, saintpaul. Shigella flexneri,
  Staph. aureus toxin

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2007 Data Update

• Twelve (12) additional outbreaks associated with
  unpasteurized dairy are reported (15 dairy
  outbreaks total)
• 1/12 Salmonella spp (liquid milk)
• 2/12 Brucella (cheese)
• 9/12 Campylobacter spp (7 liquid milk, 2 cheese)
• Little variation in pathogens from year to year

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2007 Update

• California, Kansas, Pennsylvania 2 outbreaks
• Colorado, Georgia, New York, North Carolina,
  Utah, Washington 1 outbreak each

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Results

• 22 outbreaks associated with homemade cheese or
  queso fresco
• Queso fresco is a soft, Mexican-style cheese
  traditionally made with unpasteurized milk
• 9 outbreaks in California

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Results

• Odds Ratio
• Unpast. Illness Past. Illness
• Legal 751 709
• Illegal 356 913
• OR 2.7165 95 CI 2.3154 3.1872

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Discussion

• 47/62 (75)outbreaks linked to unpasteurized or
  probable unpasteurized dairy linked to
  Campylobacter (jejuni 30/47)

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Discussion

• Unpasteurized Dairy Outbreaks in states
  associated w/ SECEBT
• Legal Status
• Alabama 0 2
• Georgia 1 2
• Florida 0 1(2)
• Mississippi 0 3
• North Carolina 2 1(2)
• South Carolina 0 4
• Tennessee 0 2
• Among the first states to pass laws expressly
  prohibiting animal shares in 2005. Considered a
  Category 2 state for the majority of the analysis

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Discussion

• NC Outbreak
• Robeson County, November 2001
• Unpasteurized liquid milk being served at a
  school
• 202 ill, 33 hospitalized
• E. coli O157H7 with 4 cases HUS
• Outbreak resulted in written policy change that
  non-commercial foods may not be brought into or
  served in county schools

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MANY THANKS TO

• State and local health department investigators
  and eFORS reporters
• Staff of the Enteric Diseases Epidemiology Branch
• Tracy Ayers, Michael Lynch, Fred Angulo, Ann
  Schmitz, Julian Grass, Heather Bair-Brake, Adam
  Langer
• Greg Podolej, Stic Harris
• Dr. Barrett Slenning, Dr. Jay Levine, Dr. Maria
  Correa, Dr. Prema Arasu, NCSU-CVM

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• All slides created by Tracy Ayers and used in a
  presentation to the Council of State and
  Territorial Epidemiologists are designated by the
  CDC logo
• The findings and conclusions in this presentation
  have not been formally disseminated by the
  Centers for Disease Control and Prevention and
  should not be construed to represent any agency
  determination or policy