Bird Flu: The Coming Pandemic Or Much Less?

July 15, 2006

By CHRISTINE HEINRICHs

Highly Pathogenic A (H5N1) Avian Influenza (AI) is killing birds and occasionally infecting and killing humans. This story continues to develop as both breaking news and a continuing story involving commercial poultry industry, ethnic differences, rural life, Third World poverty, and global and domestic preparedness for a disease pandemic.

"There is no evidence it will be the next pandemic," Dr. Julie Gerberding, head of the Centers for Disease Control and Prevention in Atlanta, said of avian flu at a recent conference in Tacoma, Wash.

Gerberding added there is "no evidence it is evolving in a direction that is becoming more transmissible to people."

Avian flu stories can be localized since many readers, viewers, and listeners care about the birds in our midst: small flocks of chickens, pet birds, and migratory birds. Scientific investigation has turned up little H5N1 in those groups, but they are frequently cited as carriers and hosts of the virus. Owners of small flocks of chickens dot the United States. Some are back-to-the-landers raising chickens for their own use and income from farmers' markets, some are selling to niche markets in organic and heirloom breed fowl, some are hobbyists. Youngsters who are in 4-H and Future Farmers of America still raise and show poultry. And cock fighting remains a large underground gambling practice.

H5N1 avian influenza has been around for years, possibly as long as 40. It came to attention in 1997 when infected chickens began dying in Southeast Asia. The response of governments was to kill all the chickens within a certain radius of a confirmed case of H5N1. The theory was that the virus would be stopped if there weren't any birds to catch it or pass it on.

The reality under that policy is that not all birds get killed. In countries that have feral populations of chickens, birds evade capture. Rural farmers conceal their birds. Government workers charged with this onerous task don't always follow through with biologically secure methods of disposal of the avian carcasses. Trucks used to transport dead birds may not be disinfected, making them carriers of the disease they are intended to end.

Occasionally, a person catches the flu from a bird. Since 1997, more than 100 deaths have been reported. The virus appears to be highly lethal to humans. However, a study in the January issue of The Archives of Internal Medicine suggests that in Vietnam, more people may have been infected and recovered than have been officially reported.

The public health concern is that this virus will mutate into a form that is easily transmissible among humans, swirling around the globe leaving devastation in its wake. After the spectacle of disasters like the 2004 tsunami and Hurricane Katrina, disaster preparedness has piqued more interest from audiences. New York Times reporter Gina Kolata's 2001 book, "Flu: The Story of the Great Influenza Pandemic" awakened interest in pandemics. The Times published a major takeout on avian flu in its Science section March 28. It examined reports circulating about major bird die-offs in China and Mongolia, determining that they are either unsupported or far less devastating than rumored. One of the veterinarians quoted said, "The disease is self-limiting in wild birds."

Besides killing off domestic flocks when infection strikes, some governments are opting to prevent the spread of avian flu through the vaccination of poultry. Vietnam, China, The Netherlands and France have begun vaccinating commercial birds and recommending vaccination for small flocks as well.

Merial, a joint venture between Merck & Co. and sanofi-aventis, is one of the companies manufacturing vaccines against many forms of avian influenza. Merial's Trovac AIV H5 vaccine is recognized by the U.S. government as an effective vaccine against the H5N1 virus. According to company spokesman Steve Dickinson, the company has the capacity to produce 50 million doses a month, if the U. S. government decides to use vaccines to contain H5N1 instead of mass culling. Merial bid unsuccessfully for the French contract.

"Every decision to use vaccine is driven by the containment strategies of the government," he said.

Vaccination of poultry is controversial. The most commonly used method to detect H5N1 involves a test for antibodies to the virus. Thus, both vaccinated and infected chickens test positive. This has implications under international trade rules for monitoring and eliminating avian influenza, which ban imports of poultry that tests positive for antibodies. A new method of testing, the Rapid Polymerase Chain Reaction, can differentiate between infected and immunized birds, but RPCR is not in general use for poultry yet.

Countries are responding in a variety of ways to control avian influenza. In the wake of devastating culling episodes, Vietnam and China began vaccinating, despite trade concerns. The action has significantly curtailed the outbreaks in those countries.

France has introduced mass vaccinating with no further outbreaks. Dutch officials, meanwhile, are unwilling to exempt vaccinated poultry from culling in the event of a confirmed H5N1 case – and this policy is slowing vaccination in The Netherlands.

How H5N1 spreads is in dispute. At Quinhai Lake in China, migratory waterfowl were investigated as possible victims and carriers of H5N1. But the lake has many commercial poultry operations on its shores along with a fish farm where chicken manure may be used as fertilizer and feed, according to a paper published by GRAIN, an international NGO promoting sustainable management and agricultural biodiversity (www.grain.org.) GRAIN and BirdLife International, a global partnership of conservation organizations (www.birdlife.net,) offer research that shows H5N1 spreading along major roads and rail lines, following commercial distribution rather than migratory routes.

In much of the world, small-scale poultry operations are an important part of the economy for rural poor, providing nearly a third of the protein in the diet. The Lancet Infectious Diseases, a British medical journal, notes that little of the funding pledged is dedicated to education or compensation to farmers for dead birds. GRAIN has issued a report on the effects on rural economies (see www.grain.org/articles/?id=12). Meanwhile, Gary Butcher, professor of poultry diseases at the University of Florida, has seen poultry consumption plummet, even in countries that have not reported any cases of AI. He consults in the Middle East and Asia on poultry diseases, including AI.

Books are appearing on the subject and provide a trove of scientific background. Dr. Marc Siegel, associate professor at New York University School of Medicine and a practicing internist, followed his 2005 book, "False Alarm: The Truth about the Epidemic of Fear" with "Bird Flu: Everything You Need to Know about the Next Pandemic" this year. It includes a bibliography. Lindsey Hillesheim has written "Dead Birds Don't Fly: An Avian Flu Primer for Small-Scale Farmers," for the Institute for Agriculture and Trade Policy (www.iatp.org.)

Everyone is a stakeholder in an influenza pandemic, as we all are in global warming. The varied economic and social strings that connect us require broader and deeper information to inform decisions that will protect us all.

Resources:

• Gary Butcher, University of Florida, (352) 392-4700 ext. 5695, ButcherG@mail.vetmed.ufl.edu • Tracy S. DuVernoy, DVM, MPH, Dipl. ACVPM, USDA, APHIS, VS, Emergency Management, 4700 River Road, Unit 41; 5D16, Riverdale, MD 20737-1231, (301) 734- 7781, cell: (240) 508-8619, tracy.s.duvernoy@aphis.usda.gov • The Council for Agricultural Science and Technology, organization of professional organizations, (515) 292-2125, www.cast-science.org • International Society for Infectious Diseases, www.promedmail.org •Merial, Steve Dickinson, (678) 638-3682, Steve.Dickinson@merial.com • www.grain.org/briefings/?id=194 • www.theregister.co.uk/2006/03/22/bird_flu_receptor/

Websites of interest

• www.usda.gov
• www.pandemicflu.gov/
• www.cdc.gov/flu/avian
• www.fao.org
•www.oie.int/eng/en_index.htm
• www.who.int/csr/disease/avian_influenza/en
•www.docuticker.com/2006/03/avian-flu-crisiseconomic- update.html •www.nal.usda.gov/awic/aflu/Avian%20Influenza.htm