Agriculture Reference
In-Depth Information
1
Enteric Human Pathogens Associated
with Fresh Produce: Sources, Transport,
and Ecology
Robert E. Mandrell
Introduction
Now in the cold parts of the country, don't you think people get to wanting
perishable things in the winter—like peas and lettuce and caulifl ower? In a big
part of the country they don't have those things for months and months. And
right here in Salinas valley we can raise them all the year round. … Do you
know we could ship lettuce right to the east coast in the middle of winter?”
John Steinbeck
In 1952, John Steinbeck through his character Adam Trask in “
East of Eden
” com-
mented on the desirability of fresh produce and the uniqueness of the climate and soil
conditions of the Salinas Valley of California for providing leafy greens and other
vegetables year-round to the rest of the nation. The development of this region on the
central coast of California, known as the “Salad Bowl of America,” is linked closely
to the growth of fresh produce consumption in the U.S. as a result of increased sea-
sonal availability, new varieties of domestic and imported produce, and increased
interest in the nutritional and health benefi ts of fresh produce (Clemens 2004). The
growing global economy has continued demand for fresh produce and involves ship-
ping produce long distances rapidly. Increased mechanization and effi ciency of pro-
duction, new and improved cultivars, and new chemicals to treat plant disease and
new products have been developed to meet this demand. Minimally processed, bagged
produce is a relatively recent new product to help meet the growing demand for fresh
produce (USDA- ERS 2001 ).
An unintended consequence of increased consumption of fresh and bagged produce,
however, is an increase in illnesses and outbreaks, including some multistate and
multicountry outbreaks. Some of the higher profi le outbreaks have been caused by
E. coli
O157:H7-contaminated leafy vegetables, in addition to outbreaks caused by
Salmonella
- contaminated tomatoes, cantaloupe, and other produce items. Investigations
of some of these outbreaks have led some to conclude that contamination occurred
probably in the fi eld, i.e., preharvest contamination (CalFERT 2007a,b, 2008; Hedberg
and others 1999; Gupta and others 2007; Greene and others 2008; Castillo and others
2004 ).
The leafy green outbreaks appear not to be associated simply with an increase in
consumption. Leafy green consumption between 1996 and 2005 increased 9% com-
pared to the previous decade, but outbreaks associated with leafy greens increased
38.6%, with a majority of them caused by
E. coli
O157:H7 (Herman and others 2008).
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