A recall occurs when a firm voluntarily removes product (i.e. contaminated meat) from channels of distribution. This is done to protect the public from consuming adulterated products.
The USDA’s Food Safety and Inspection Service performs random testing at meat production plants around the US. In an effort to prevent foodborne illness outbreaks, when potentially contaminated meat is identified, FSIS requests the recall of the product from all channels of distribution.

While recalls are an important step in removing a product from consumer channels, they are not wholly effective. There is often a time gap between the time a shipment of contaminated food reaches consumers and when the recall is issued, and some recalls are not put into effect until after outbreaks of foodborne illness have been identified by health departments and the CDC.
Each strain of E. coli, much like each human, has a unique “fingerprint” which it can be identified by. When E. coli O157:H7 outbreaks occur, scientists at labs across the country perform DNA fingerprinting by Pulse Field Gel Electrophoresis (PFGE). PFGE testing helps scientists determine whether strains of E. coli bacteria isolated from the stool of people who have become ill with E. coli infection can be linked to food contaminated with bacteria with the same fingerprint.
A national network of public health laboratories that performs DNA fingerprinting on foodborne bacteria, PulseNet, was developed by CDC to serve as an early warning system for detecting outbreaks of foodborne illness before they become widespread. PulseNet identifies and labels each fingerprint pattern and permits rapid comparison of patterns from human illnesses through an electronic database at the CDC.
By identifying the fingerprint of one strain of E. coli that can be linked to one product and many people, that product can be recalled, and the hope is that large E. coli outbreaks can be prevented.