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Vaccine
a breakthrough in fight against E. coli
Source
of Article: http://www.capitalpress.info/main.asp?SectionID=75&SubSectionID=767&ArticleID=49767&TM=58133.16
It's not the silver bullet,
but the new vaccine that causes cattle to shed Escherichia Coli O157
bacteria as dead bits of matter comes close. Conditional approval of the
vaccine developed by Epitopix, a Minnesota animal pharmaceutical
laboratory, was announced earlier this month at the Beef Industry Food
Safety Conference.
As we understand the science, the vaccine, administered to feedlot cattle
before slaughter, interrupts the flow of iron, an essential nutrient, to E.
coli living in the gut. That means that in a high percentage of treated
animals, there's no living bacteria shed in manure. Epitopix hasn't set a
price, but promises the per dose cost "will be reasonably
priced."
From the time that the toxic strain of E. coli O157:H7 first surfaced in
1993 - traced to hamburger patties from a Washington state fast food
restaurant and blamed for the deaths of four children - the beef industry,
food processors and restaurant operators have invested millions of dollars
in research. Discovery of contaminated ground beef has put more than one processor
out of business.
E. coli is naturally occurring. Proper cooking of meat kills the organism
before human consumption. The same bacteria has also, from time to time,
turned up on fresh produce.
As research went forward, other subspecies of the O157 variety, in addition
to H7, were found to be highly toxic to humans. That caused scientists to
seek a cattle vaccine that works against known O157 subtypes.
The 2007 feedlot trials of the Epitopix vaccine were financed by the
National Beef Checkoff, a $1 a head fee paid each time cattle change
ownership. This amounts to a big research payoff for dairy and beef
producers, who since 1993 have invested $27 million in research fighting
this pathogen.
While the vaccine represents a breakthrough, drastically lowering the risk
that E. coli will be shed by an animal heading for slaughter, it's no time
to dismantle the elaborate set of safeguards the industry and government
regulators created over the past two decades. Epitopix, in its news release
announcing U.S. Department of Agriculture's conditional license for the
vaccine, is very careful to use the words "reduce the prevalence"
rather than "eliminate" E. coli.
USDA made the license conditional so the company and the industry can move
to large-scale tests on the potency of the vaccine and be more specific on
how dependable it may be. The vaccine is an extract of a bacteria that
blocks iron uptake in E. coli. The first time the material was tried in a
Kansas State University feedlot situation, it decreased shedding of E. coli
by 54 percent. When the research team at Kansas State and West Texas
A&M University increased the dose, shedding of E. coli was knocked down
by 85 percent.
Guy Loneragan, who headed the Texas portion of the trials, said at a beef
research meeting last year that 85 percent kill rate means handling the
remaining bacterial is "within the capacity" of the suite of
in-plant safety measures used by packers. They range from washing hides
before and after slaughter to in-plant carcass spray washes and microbial
laboratory testing during carcass handling.
Kansas State's lead scientist on the project, Dan Thompson, said of the
vaccinated cattle still shedding bacteria, "we observed nearly a 98
percent reduction of E. coli O157 fecal concentration."
That's manageable at a packinghouse, but it's still no reason to let up on
consumer education in proper cooking of food, nor in washing fresh produce
before consumption.
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