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Are pill-popping turkeys a danger?
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Antibiotics are approved to treat sick turkeys and to
keep disease from spreading.
Treating poultry (and other food
animals) with antibiotics could lead to some serious health consequences for
human beings.
By Karen Ravn
November 24, 2008
Source of Article: http://www.latimes.com/features/health/la-hew-turkeybiotics24-2008nov24,0,6337742,full.story
Turkeys, like any other animal,
get sick. And while few would dispute that they should be treated when that
happens, many scientists, medical professionals and animal experts are
concerned that too much medicine is being given to too many turkeys -- and to
too many food animals in general.
"The use and misuse are rampant," says Bill Niman,
founder of Niman Ranch in Northern
California and a member of the Pew Commission on Industrial Farm
Animal Production.
Those concerned fear that the
practice will have serious consequences for human health care -- and that
some of those consequences are already starting to show up.
Antibiotics are approved in turkeys both for therapeutic use (meaning, to
treat sick turkeys) and for disease prevention -- which usually means the
rest of the flock will also be treated to keep the disease from spreading.
Antibiotics are used in this same way in other food animals, and in some
cases they're also used for growth promotion, although that's not supposed to
be done with turkeys.
The potential for danger from antibiotic use in farm animals comes in two
forms, experts say: The antibiotics could remain in meat when people eat it.
They could also contribute to the development of resistant bacteria.
If people are getting a dose of antibiotics every time they have a hamburger
or a piece of chicken -- or a turkey drumstick -- this exposure could
possibly be harmful. We all have benevolent bacteria in our bodies, and the
antibiotics we eat could kill those good bacteria. Also, some people are
sensitive to antibiotics, with reactions ranging from diarrhea to itching to
seizures, and they could have these reactions to the food they eat.
Even critics of antibiotic use see this danger as minimal, at least in
turkeys. A withdrawal time has been established for every antibiotic, based
on testing how long it remains in the bird after usage has stopped. So if the
withdrawal time is, say, two weeks, the antibiotic cannot be given for at
least two weeks before the turkey goes to market.
Besides, the Food and Drug Administration and U.S. Department of Agriculture
routinely examine the turkeys for residue of the drugs, says Sherrie
Rosenblatt, spokeswoman for the National Turkey Federation, and on average,
the birds are found to be 99.9% residue free.
The second concern -- that of antibiotic resistance -- has many more
scientists worried. Resistance develops when antibiotics kill off some of the
bacteria they're supposed to, but not all -- so only the super-strong
survive. If this happens enough, the susceptible bacteria are wiped out, but
a strain of resistant bacteria takes over in their place, and the antibiotics
that used to work don't work any longer.
The Centers for Disease Control and Prevention calls antibiotic resistance
one of its top concerns.
"There are bacteria that were once treatable with antibiotics that are
now resistant to everything," says microbiologist Lance Price, director
of metagenomics and human health at the
Translational Genomics Research Institute in Phoenix.
No one doubts that much of the problem stems from improper or unnecessary
antibiotic use by humans -- say, to treat viral infections like colds and
flu. But Price says that part of the problem is certainly due to agricultural
use.
One example is the use of fluoroquinolones to treat
Campylobacter in chickens, says Dr. Sherwood Gorbach,
distinguished professor of public health and medicine at Tufts University
School of Medicine in Boston.
Campylobacter is the leading cause of bacterial diarrhea in the United States,
and is typically treated by the fluoroquinolone Cipro. But since the mid 1990s, resistance to Cipro has gone up from 2% to 20% or even higher, Gorbach says. And he believes it's due to the use of Baytril, the form of the drug used in chickens.
The government found the drug troubling too. In 1996, the National Antimicrobial
Resistance Monitoring System was created to monitor human and animal
resistance to 17 antimicrobials (antibiotics, antivirals,
antifungals and antiparasitics).
And in 2005, using data from the monitoring system, the FDA banned the use of
fluoroquinolones in poultry in order to reduce the
prevalence of resistant Campylobacter.
Price led a team at the Bloomberg School of Public Health at Johns Hopkins
University in Baltimore that studied the effectiveness of
this ban by comparing Campylobacter resistance rates in 2004 and 2006. In a
study published last year in Environmental Health Perspectives, the team
tested chicken products from two conventional producers and three
antibiotic-free producers -- 198 packages in 2004 and 210 in 2006 -- and found
no significant change in the resistance rates.
But they did find that the Campylobacter from the two conventional producers
were significantly more likely to be resistant than those from the
antibiotic-free producers.
The team concluded that resistant strains of bacteria may continue to
contaminate poultry products even after the drug is no longer being used.
How many antibiotics are used in agriculture? That is hard to estimate,
scientists say, because there is no requirement to report this use.
"We . . . have no knowledge about how they are being used in the field,
i.e., whether it is common practice to use them on a regular basis,"
says Siobhan DeLancey in the FDA Office of Public
Affairs in Washington, D.C.
In 2001, the Union of Concerned Scientists, a Washington, D.C.-based
nonprofit that advocates for a healthy environment, estimated that every year
in this country 3 million pounds of antimicrobials are used in human
medicine. By contrast, the organization estimated that 24.6 million pounds are
used in food animals for nontherapeutic purposes:
about 10.5 million pounds in poultry, 10.3 million pounds in hogs and 3.7
million pounds in cattle.
In poultry, the organization found, use had shot up since the 1980s, from 2
million to 10.5 million pounds, and only 40% of that increase could be
attributed to growth in the poultry industry.
An earlier study by the Animal Health Institute came up with a much lower
figure for agricultural use: 17.8 million pounds for therapeutic and nontherapeutic uses in all animals, not just poultry,
hogs and cattle.
"But no one would challenge that we're using far more in agriculture
than in human medicine," says Margaret Mellon, director of the food and
environment program at the Union of Concerned Scientists.
Some view antibiotics as key to growing healthy turkeys in large numbers,
which is not to say they believe in using the drugs willy-nilly.
In fact, growers have strong incentives to use as few as possible, says
Francine Bradley, extension poultry specialist in the Animal Science
Department at UC Davis. "They cost a lot of money, so no one gives them
indiscriminately. Besides if they've overused them previously, they won't get
a good response when they really need them."
But growers do need them sometimes, and not only to treat sick birds, but to
keep the disease from spreading to the whole flock, says Daniel Fletcher,
head of the Animal Science Department at the University of Connecticut.
Without them, costs would go up and price many people out of the meat market.
"If we didn't use antibiotics," he says, "we'd have a tough
time meeting the nutritional needs of people in this country."
Gorbach says there's a bill before Congress right
now intended to allow more use of fluoroquinolones
in chickens again and adds, "We feel very strongly that's the wrong
thing to do."
Other studies also point toward dangers from antibiotic use in food animals.
* One, published in 2007 in the journal Foodborne
Pathogens and Disease, found a possible link between the meat women eat and
their chances of getting a urinary tract infection caused by drug-resistant Escherichia
coli (E.coli).
In it, a team from UC Berkeley studied 99 women, comparing those with urinary
tract infections caused by drug resistant E. coli to those with urinary
tract infections caused by nonresistant E. coli. They found that women
infected with E. coli resistant to multiple antibiotics ate chicken
more often than the others. They also found that women infected with either ampicillin-resistant or cephalosporin-resistant E.
coli ate pork more often.
The researchers concluded that the antimicrobial-resistant E. coli that
cause urinary tract infections may come from poultry, pork or both.
* And in June, a study presented at the annual meeting of the American Society
for Microbiology in Boston found potentially
deadly methicillin-resistant Staphylococcus aureus -- or MRSA -- in nearly half of the 299 pigs
tested on 10 farms in Iowa and Illinois, as well as
in nine of the 20 farm workers they tested. (The study has not yet been
published.)
Study lead author Tara Smith, an assistant professor of epidemiology at the University of Iowa, has speculated that the
tetracycline used in hog farming may be responsible.
Yet in spite of such studies there remains no conclusive evidence that
antibiotic use in food animals is to blame. And some believe it's all just a
tempest in a turkey barn.
"Some people have an agenda against farm animals," says Murray
Bakst, research physiologist at the Agricultural Research Service in Maryland.
"There's more of a danger from people flushing antibiotics down the
toilet than from the antibiotics in animal feed."
Ravn is a freelance writer.
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