Dissecting the Science Behind Salmonella, Listeria and E. coli Claims

An Examination of How the Science Links to Causation and Opens the Door to Liability

William D. Marler, Esq.

To Put Things in Perspective

• According to the CDC, pathogens in food cause an estimated 48 million cases of human illness annually in the United States

• 125,000 hospitalized

• Cause up to 3,000 deaths

• Illnesses from food poisoning pose a $75 to $125 billion economic burden in the United States annually

Estimates Differ From Actual Counts

• Annual E. coli O157:H7

Estimates:

– 62,000 illnesses

– 1,800 hospitalizations

– 52 deaths

Bottom Line: Most Victims Never Linked

E. coli O157:H7Patterns Submitted 5,376Clusters Identified 67Multi-state Clusters 36Epi Investigation 19Vehicle Implicated 4Regulatory Activity 4

Ill person

Specimen collection

The Long Pathway of a Foodborne Illness Investigation

Health Care Provider

Organism identified

Ill person

Organism identified

Specimen collection

The Pathway Continued

Health Care Provider

Epidemiologic investigation

Public Health Laboratory

If there are more ill persons than expected, an

OUTBREAK might be underway

Ill person

Organism identified

Specimen collection

Pathway of a Foodborne Illness Investigation

Health Care Provider

Epidemiologic investigation

Public Health Laboratory

Environmental investigation

Product Trace BackPRODUCT RECALL

Proving a Case Using Lab Tests

• All states require reporting of tests for a number of pathogens, including;

– E. coli O157:H7

– Salmonella

– Shigella

– Listeria

– Hepatitis A

– Campylobacter

• The process of obtaining the DNA fingerprint is called Pulse Field Gel Electrophoresis (PFGE).

Proving a Case with PulseNet

• PulsetNet is an early-warning system for outbreaks of foodborne disease.

• Using this system scientists at labs throughout the country can rapidly compare the PFGE patterns of bacteria from ill persons to help determine where the outbreak occurred.

Proving a Case Using PFGE

• The PFGE pattern of bacteria isolated from contaminated food can be compared and matched to the PFGE pattern of the strain isolated from the stool of infected persons.

• When paired, PFGE and epidemiological evidence are extremely potent in supporting causation.

Causation - Science

• “Causation is an essential concept in epidemiology, yet there is no single, clearly articulated definition ….” J Epidemiol Community Health 2001Dec;55(12):905-12; Parascandola M, Weed DL.

• Confidence Interval (CI) – Range within which 95% of times the true value of the estimated association lies (95% CI)

Causation – The Law

• “A proximate cause of an injury is a cause which, in natural and continuous sequence, produces the injury, and without which the injury would not have [likely] occurred. The concept of proximate causation has given courts and commentators consummate difficulty and has in truth defied precise definition.” Prosser, Torts, pp. 311-313

• However, “It really is what is more likely than not. It is 50% and an extra grain of sand.” Marler on the law

Resources

• Food Safety News

• Foodborne Illness Outbreak Database

• Marler Blog

• Occupy Food Safety

Questions?