*Dr. Greger's Pandemic Update: April 2007*
Michael Greger, M.D.
Dr. Greger's Pandemic Update: April 2007
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CONTENTS
I. Dr. Greger's Multimedia Presentation Now Online
II. Is This Your Best Shot? FDA Approves First H5N1 Vaccine
III. Fly in the Ointment: Illusions of Biosecurity
IV. Restocking the Global Flock: Realigning Poultry Breeding
Priorities
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I. Dr. Greger's Multimedia Presentation Now Online
First, let me apologize for missing March's Pandemic Update--my
speaking schedule has been overwhelmingly hectic. Just last week, for
example, I gave 11 presentations in 3 states in 5 days! This year, I
am planning over 100 cities in 4 countries (confirmed engagements to-
date at http://birdflubook.com/events.php). If your city is not on the
list, a version of my presentation can now be viewed online.
The University of Wisconsin School of Medicine and Public Health
videotaped my presentation there last week and put it in its public
video library at http://videos.med.wisc.edu/videoInfo.php?videoid=241.
Warning: Some of the images (such as the footage from 1918) are
disturbing and may not be appropriate for all ages.
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II. Is This Your Best Shot? FDA Approves First H5N1 Vaccine
Last week, the Food and Drug Administration (FDA) approved the first
human H5N1 vaccine. According to the vaccine's maker, Sanofi Aventis,
it is "a significant milestone in pandemic preparedness." The head of
the FDA's Office of Vaccines Research and Review was less
enthusiastic, referring instead to the vaccine as "sort of an interim
measure" until better vaccines were created.[1]
This is the same "vaccine for the happy few" that I wrote about in
BIRD FLU (http://birdflubook.com/a.php?id=83). Even at the maximum
dose--two separate injections of 90µg, compared to the single shot of
15µg in the annual flu vaccine--less than half of those injected
showed an antibody response presumed to be protective. The larger the
required dose, the fewer that can be produced in time. At that dose,
even if the entire U.S. vaccine production system were dedicated to
making this one vaccine, in one year only a small fraction of the U.S.
population would be covered. "Needing two doses of 90µg is the worst-
case scenario," noted a leading virologist. "You are not going to get
very far with that."[2]
Also important to recognize is that this vaccine is for a bird virus,
not for what concerns us: a human pandemic virus. An H5N1 human
pandemic virus does not currently exist (thankfully!). Every major
vaccine manufacturer in the world is experimenting with developing
vaccines against avian strains of the virus in hopes that there will
be some kind of cross-protection should one of those avian strains
mutate into a human form capable of triggering a pandemic.[3]
Many, including myself, think this is a gamble we ought to take (in
fact I'm actually participating in a trial of the Sanofi vaccine here
at the National Institutes of Health). The fact that even at the
maximum dose, though, less than half responded to a vaccine matched to
a 2004 Vietnamese chicken virus (not even to the potentially more
concerning "clade 2" H5N1 viruses in Indonesia and Nigeria) does not
bode well. Responding to Health Secretary Leavitt's characterization
of the Sanofi vaccine approval as "a sign of progress," one senior
public health scientist saw it more as of a "sign of desperation."[4]
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III. Fly in the Ointment: Illusions of Biosecurity
In "Wishful Thinking" (http://birdflubook.com/a.php?id=76), I document
the industry's admission that biosecurity standards on industrial
poultry farms leave much to be desired. University of Maryland
researchers, for example, surveyed chicken production facilities
throughout the Delaware-Maryland-Virginia peninsula--perhaps the
densest concentration of chickens in the world--and concluded that
U.S. flocks "are constantly at risk of infection triggered by poor
biosecurity practices."[5]
Despite suggestions from within the industry that U.S. biosecurity
standards are actually in decline in order to cut costs,[6] the
response to H5N1 continues to focus on calls for greater biosecurity.
Even with perfect employee adherence to measures such as antiseptic
footbaths, hand-washing, and equipment disinfection, evidence
continues to accumulate that keeping these viruses from spreading into
industrial poultry flocks may not be effectively possible.
The April 2007 issue of "Poultry International," for example, reviewed
the evidence showing that common flies may be able to transmit
influenza viruses in and out of poultry facilities.[7]
Before the emergence of H5N1, the largest outbreak of bird flu in
history wasn't in Asia; it was in Pennsylvania in 1983-84, resulting
in the costliest animal disease eradication in U.S. history and the
deaths of 17 million birds. In this U.S. outbreak of a highly
pathogenic H5N2 strain, researchers found that over one-third of
mature houseflies recovered from affected facilities were carrying the
virus. Universal fly infestation is inherent to poultry production:
One cannot effectively keep flies out of a poultry facility.[8]
In my presentations to industry academics and producers, I describe
how H5N1 is handled in the lab: Biosafety Level 3+ facilities with air
locks; shower in/shower out; all floors/walls/ceilings sealed and
waterproofed; all wall penetrations--electric outlets, phone cords--
caulked/collared/sealed to prevent air leaks; all surfaces
decontaminated daily; all solid waste incinerated. That's how we're
supposed to handle this virus. THAT is biosecurity. In contrast, the
global industrial poultry sector seems to be breeding viruses like
H5N1 at essentially Biosafety Level "zero."
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IV. Restocking the Global Flock: Realigning Poultry Breeding
Priorities
"So what can we do...realistically?" poultry producers often ask.
Certainly, a number of countries have taken steps to de-intensify the
industry, particularly in Europe, where they're phasing out
conventional cages for egg-laying hens[8] and considering decreasing
the stocking density of broiler (meat-type) chickens.[9]
"In the agricultural sector, greater account needs to be taken of the
implications of intensive animal husbandry practices," said the
European Commissioner for Health and Consumer Protection, speaking at
the conference Public Health Risks from Emerging Zoonotic Diseases.
"Public health policy needs to have a much greater role to ensure
human health protection. Policies need to encourage a shift away from
intensive rearing...at an international level."[10]
In the United States, there doesn't seem to be movement away from
greater intensification within the poultry industry, but in the pork
sector, Smithfield Foods--the largest pig producer in the world--
recently announced a phase-out of the use of gestation crates, the
veal crate-like stalls for pregnant sows.[11] Getting breeding pigs
out of crates so restrictive they cannot even turn around is certainly
a step in the right direction. Going one step further, studies suggest
that simply providing straw for pigs can significantly decrease swine
influenza transmission rates.[12] The presumed mechanism is that the
straw prevents them suffering the immunosuppressive stress of spending
their lives laying on bare concrete.[13]
Though there does not seem to be similar movement on the part of major
poultry producers in this country, there is building pressure from
major poultry buyers. In just the last few months, college dining
services, hospitals, hotels, and such major players as Burger King and
Wolfgang Puck have announced purchasing policies with improved welfare
standards[14] which could have positive impacts on both human and
nonhuman animal health.
This piecemeal, practice-by-practice or country-by-country approach,
however, is not sufficient. The most efficient way to fundamentally
change the global poultry industry may be to fundamentally change
global poultry.
In "Bred to be Sick" (http://birdflubook.com/a.php?id=72), I review
the science showing that by selectively breeding animals for
production characteristics like fast growth, we tend to shortchange
their immune function. For meat-type birds, we have produced a chicken
through selective breeding who now grows twice as big in half the time
it took 50 years ago. The trade-off, though, is that the diversion of
protein and energy into anabolic breast meat production comes at the
expense of internal organ development, including lymphoid (immune
system) tissue. In fact, today's broiler chickens can even outgrow
their cardiovascular systems. By prioritizing fatness over fitness,
we've produced birds who die of congestive heart failure in
adolescence, what's called "sudden death syndrome."[15]
In terms of the birds' immune systems, poultry scientists have
demonstrated that compared to slower-growing breeds, birds with
accelerated growth may have impaired immunity, inadequate antibody
production, and increased disease mortality.[16] You can breed for
disease resistance, but only, it seems, at the expense of growth.
The European Commission's Scientific Committee report on the welfare
of broiler chickens stated that its "most important recommendation"
was that "[b]reeders should give a considerably higher priority to
health variables in the breeding index, if necessary at the expense of
the selection pressure for growth and feed conversion."[16] Meanwhile
in the United States, growth rates continue to be pushed faster every
year[17] and we export our breeds around the world. As a result, we
are creating a global "monoculture" of birds with essentially built-in
immune dysfunction,[18] which may be facilitating the emergence and
spread of avian flu viruses with pandemic potential.
In "Monoculture" (http://birdflubook.com/a.php?id=73), I point out
that essentially all of the breeding stock for domestic poultry around
the world is supplied by just a tiny handful of corporations. This
mass consolidation offers an unprecedented opportunity to propagate
positive genetic changes throughout the world. We don't tend to shore
up the levees until after the disaster, but once the breeding industry
decides to prioritize selection for stronger immunity, in as few as
three or four years, practically the entire global flock could be
replaced with an improved disease-resistant variety of birds.[19]
Because these breeds would be slower-growing, chicken meat will likely
be slightly more expensive, but it's not worth risking the lives of
millions of people for the sake of cheaper chicken.
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REFERENCES
[1] Reuters. 2007. FDA approves Sanofi bird flu vaccine. April 17.
http://www.sciam.com/article.cfm?alias=fda-approves-sanofi-bird&chanID=sa003&modsrc=reuters.
[2] Butler D. 2005. Bird flu vaccine not up to scratch: positive
results of little practical use, experts warn. Nature News, August 10.
http://bioedonline.org/news/news.cfm?art=1964.
[3] Subbarao K and Joseph T. 2007. Scientific barriers to developing
vaccines against avian influenza viruses. Nature Reviews: Immunology
7:267-7.
[4] Effect Measure. 2007. Vaccine dreams. April 18.
http://scienceblogs.com/effectmeasure/2007/04/post_2.php.
[5] Tablante NL, San Myint M, Johnson YJ, Rhodes K, Colby M, and
Hohenhaus G. 2002. A survey of biosecurity practices as risk factors
affecting broiler performance on the Delmarva Peninsula. Avian
Diseases 46:730-4.
[6] Shane SM. 2003. Disease continues to impact the world's poultry
industries. World Poultry 19(7):22-7.
[7] Mabbett T. 2007. Another good reason to control houseflies: they
carry bird flu virus. Poultry International. April, pp. 16-7.
[8] BBC News. 1999. Battery hen cages to be outlawed. June 15.
news.bbc.co.uk/1/hi/world/europe/369555.stm.
[9] European Commission. 2005. Commission proposes legislation to
improve welfare of broiler chickens. May 31. int/rapid/
pressReleasesAction.do?reference=IP/05/637.
[10] Byrne D. 2004. Combating emerging zoonoses: challenges and
prospects at community level. Conference on Infectious Disease:
European Response to Public Health Risks from Emerging Zoonotic
Diseases, The Hague, September 17. medicalnewstoday.com/
medicalnews.php?newsid=13681.
[11] Kaufman M. 2007. Largest pork processor to phase out crates.
Washington Post, January 26, p. A06.
http://www.washingtonpost.com/wp-dyn/content/article/2007/01/25/AR2007012501785.html.
[12] Ewald C, Heer A, and Havenith U. 1994. Factors associated with
the occurrence of influenza A virus infections in fattening swine.
Berliner und Munchener Tierarztliche Wochenschrift. 107:256-62.
[13] André F and Tuyttens M. 2005. The importance of straw for pig and
cattle welfare: a review. Applied Animal Behavior Science 92(3):261.
[14] 2007. Restaurants switch pork, egg suppliers on the basis of
animal welfare. Journal of the American Veterinary Medical Association
News. May 1. http://www.avma.org/onlnews/javma/may07/070501l.asp.
[15] Martin D. 1997. Researcher studying growth-induced diseases in
broilers. Feedstuffs, May 26.
[16] European Commission Scientific Committee on Animal Health and
Animal Welfare. 2000. The welfare of chickens kept for meat production
(broilers). March 21. europa.eu.int/comm/food/fs/sc/scah/out39_en.pdf.
[17] Walker A and MacLeod M. 2004. Limits to the performance of
poultry. In: Wiseman J and Sylvester-Bradley R (eds.). 2005. Yields of
Farmed Species: Constraints and Opportunities in the 21st Century
(Nottingham: Nottingham University Press).
[18] Koenen ME, Boonstra-Blom AG, and Jeurissen SHM. 2002.
Immunological differences between layer- and broiler-type chickens.
Veterinary Immunology and Immunopathology 89:47-56.
[19] Thorp BH and Luiting E. 2000. Breeding for resistance to
production diseases in poultry. In: Axford RFE, Bishop SC, Nicholas
FW, and Owen JB (eds.), Breeding for Disease Resistance in Farm
Animals (Wallingford, UK: CABI Publishing, pp. 357-77).