*Dr. Greger's Pandemic Update: August 2007*
Speaking Tour
Dr. Greger's Pandemic Update: August 2007
*******************************************************
CONTENTS
I. World Health Organization Calls Attention to Poultry Intensification
II. What Are the Odds a Pandemic Will Strike Within the Next Year?
*******************************************
I. World Health Organization Calls Attention to Poultry Intensification
Last week, the World Health Organization (WHO) released its 2007 World
Health Report. In the introduction, WHO Director-General Margaret Chan
noted that when the WHO was founded around 60 years ago, the
infectious disease situation was relatively stable and new diseases
considered rare. "Since then," she writes, "profound changes have
occurred in the way humanity inhabits the planet." Now, the disease
situation is "anything but stable." In part because of "intensive
farming practices, environmental degradation, and the misuse of
antimicrobials," she notes that new infectious diseases are now
emerging at a rate unprecedented in the history of medicine--nearly 40
new diseases since the 1970s, approximately one new disease every
year. During the last five years, the WHO has verified more than 1,100
epidemic events worldwide.[1]
At the launch of the WHO report, she specifically singled out poultry
production. "The intensity of poultry farming is such that we really
need to look at how the human animal interface is managed. It should
not come as a surprise that we are seeing more and more disease
outbreaks coming from the animal sector."[2] Similarly, a research
report released this summer by the Food and Agriculture Organization
(FAO) of the United Nations suggests that the industrialization of
animal agriculture in recent decades is increasing public health risks
on a global scale.
In 1980, nearly all chickens in China were raised outdoors in small,
traditional backyard flocks.[3] By 1997, though, the year H5N1 arose
in Hong Kong, approximately half of the 10 billion chickens[4] in
China were intensively confined[5] in more than 60,000 industrial
facilities, a few of which raised more than 10 million chickens at a
time.[6] An article published by scientists in Vietnam and Thailand in
the "Annals of the New York Academy of Sciences" explain why such
facilities may be particularly risky:
"The large concentration of animals farmed in overcrowded conditions
in industrial batteries (several hundreds or even several thousands of
individuals in a confined space), provides an extremely infectious
context through contact with numerous pathogens, as opposed to natural
extensive or semi-extensive breeding conditions....The numbers and
density in which animals are bred result in overcrowded conditions,
which, among other things, stress the animals, modify their metabolic
performances, weaken their immune system, and above all maintain a
high risk of hyperinfection by massive infectious loads....Where a
small infectious dose would naturally be controlled by a normal immune
system, there is no chance, even for an efficient immune system, of
controlling huge infectious doses which "saturate" defense effector
mechanisms and "overflow" the animals' immune mechanisms...."[7]
The scientists offer a potential solution: "Possible alternatives that
would reduce the risks of contact could for instance include replacing
large industrial units with several smaller-scale production units
containing lower densities of animals. In other words, this means
favoring product quality over industrial yield. There are many
advantages to this: animals would be less stressed and thus more
resistant to infectious aggressions; contact between individuals would
be less intense, which would reduce infection rates since infectious
doses would be lower."[8]
The FAO report "Industrial Livestock Production and Global Health
Risks" is available at
http://www.fao.org/ag/AGAinfo/projects/en/pplpi/docarc/rep-hpai_industrialisationrisks.pdf
and an earlier paper this year echoing much of this growing awareness,
"The Potential Role of Concentrated Animal Feeding Operations in
Infectious Disease Epidemics and Antibiotic Resistance," can be
downloaded at http://www.ehponline.org/members/2006/8837/8837.pdf
-----------------------------------------------------------
II. What Are the Odds a Pandemic Will Strike Within the Next Year?
In the 2007 World Health Report, the World Health Organization
reiterated that an influenza pandemic currently poses the greatest
threat to international public health and that the "question of a
pandemic of influenza from this virus [H5N1] or another avian
influenza virus is still a matter of when, not if."[9]
Because another pandemic is considered inevitable does not, however,
necessarily mean that one is imminent. I am commonly, and
understandably, asked at presentations and meetings to hazard a guess
as to when the next flu pandemic might likely hit. I explain to their
dissatisfaction that we do not know enough about the biology of these
viruses to make accurate predictions, unfortunately. Yet, as pandemic
contingency planners need to rely on some sort of estimate, there is
no shortage of speculation.
The British Government is working off the assumption that the
probability a human flu pandemic will strike in any given year is 3%,
based simply on the fact that in the last 100 years there have been
three pandemics. Described as "dangerously optimistic,"[10] this
estimate does not take into account the rather unique circumstances we
now find ourselves in with the unprecedented spread of H5N1. A review
at an international summit of avian flu experts reportedly put the
contemporary risk of a pandemic during the next year between
5-20%.[11] The University of Iowa Health bird flu futures market is
currently predicting the odds of a pandemic by July 1, 2008 at 8%.[12]
We should not let this uncertainty lead to complacency--if anything,
it should make us more vigilant to work on preparing our communities
for the coming pandemic. Retired Lieutenant General Peter Taylor is a
crisis management planner for the U.S. Centers for Disease Control and
Prevention. He recently stressed the need for personal responsibility
for pandemic preparation. "You need to have your own plan, each of us
with our families," he said. "If you think the federal government is
going to ride in on a white horse, let me disabuse you of that
idea."[13]
*******************************************************
REFERENCES
[1] World Health Organization. 2007. The World Health Report 2007. A
Safer Future: Global Public Health Security in the 21st Century
(Geneva: WHO). http://www.who.int/entity/whr/2007/whr07_en.pdf.
[2] Deutsche Presse-Agentur. 2007. Poultry farming must be
re-examined: WHO. http://www.eux.tv/article.aspx?articleId=13235.
[3] Bingsheng K. 1998. Industrial livestock production, concentrate
feed demand and natural resource requirements in China. (Beijing,
China: China Agricultural University).
[4] Food and Agriculture Organization of the United Nations. 2007.
FAOSTAT. Rome, Italy.
[5] Bingsheng K. 1998. Industrial livestock production, concentrate
feed demand and natural resource requirements in China. (Beijing,
China: China Agricultural University).
[6] Simpson JR, Shi Y, Li O, Chen W, and Liu S. 1999. Pig, broiler and
laying hen farm structure in China, 1996. Proposal to International
Agro-Hydrology Research and Training Centre (IARTC) International
Symposium, June 25-26.
[7] Maillard J-C and Gonzalez J-P. 2006. Biodiversity and emerging
diseases. Annals of the New York Academy of Sciences 1081(1):1-16.
[8] Maillard J-C and Gonzalez J-P. 2006. Biodiversity and emerging
diseases. Annals of the New York Academy of Sciences 1081(1):1-16.
[9] World Health Organization. 2007. The World Health Report 2007. A
Safer Future: Global Public Health Security in the 21st Century
(Geneva: WHO).
[10] Donnelly L. 2007. Risk of bird flu pandemic 'greater than
claimed.' Sunday Telegraph. August 20.
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/08/19/nbirdflu119.xml.
[11] Donnelly L. 2007. Risk of bird flu pandemic 'greater than
claimed.' Sunday Telegraph. August 20.
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/08/19/nbirdflu119.xml.
[12] University of Iowa. 2007. Avian Influenza Prediction Market.
August 23. http://fluprediction.uiowa.edu/fluhome/AvianFlu_Graphical.cfm.
[13] Gilbert M. 2007. General urges personal bird flu strategies.
Killeen Daily Herald, June 23.