Order Code RS21747
Updated August 29, 2006
CRS Report for Congress
Received through the CRS Web
Avian Influenza: Agricultural Issues
Analyst in Agricultural Policy
Resources, Science, and Industry Division
A strain of highly pathogenic avian influenza (H5N1) has spread throughout Asia
since 2003, infecting mostly poultry but also a limited number of humans. The virus
reached Europe in 2005, and the Middle East and Africa in 2006. Officials believe this
strain may enter North America later in 2006 through migratory flyways. Avian flu is
highly contagious in domestic poultry, prompting strict biosecurity measures.
International trade restrictions can cause significant economic effects.
A different strain of H5N1 was found in wild swans in Michigan in August 2006.
This low pathogenicity strain does not pose the same threat as highly pathogenic H5N1.
Controlling avian flu in poultry is seen as the best way to prevent a human
pandemic from developing, by reducing the number of animal hosts in which the virus
may evolve. This report mainly covers avian flu in poultry, and will be updated.
Two Forms with Many Strains
Avian influenza (AI) viruses exist throughout the world in many different strains.
Avian flu is an Influenza A virus that infects birds, and certain strains have been known
to infect both animals and humans. Avian flu is characterized by two forms in birds:1
a low pathogenicity (LPAI) form that causes mild illness, and
a highly pathogenic (HPAI) form that is extremely contagious, causes
severe illness, and frequently has high rates of mortality.
Both forms are possible in several strains, designated by the letters H and N.2 Some
low pathogenicity strains (H5 and H7) can become highly pathogenic, and thus are treated
aggressively. In Italy in 1999, an H7 LPAI virus mutated into HPAI within nine months.
Pathogenicity is determined by genetic sequencing, and by inoculating healthy chicks and
monitoring them. HPAI mortality ranges from 30-100%; LPAI mortality is usually less than 20%.
Surface proteins, called hemagglutinin and neuraminidase, are abbreviated H and N. Sixteen
H subtypes and nine N subtypes have been identified. They can occur in any combination.
Congressional Research Service ˜ The Library of Congress
Low pathogenicity outbreaks are not unusual since LPAI is endemic in wild birds.
The most recent cases in U.S. poultry were in 2004 with LPAI strains of H7N2 in
Delaware, Maryland, and New Jersey, and H2N2 in Pennsylvania. An H5N2 strain
classified as HPAI was found in Texas, although it did not manifest as such. Other cases
include low pathogenicity H7N2 in the Northeast in 2003, and in the mid-Atlantic in
2002. Only three HPAI outbreaks have occurred domestically (1924, 1983, and 2004).
Status of Avian Influenza Outbreaks
In the United States.3 The highly pathogenic H5N1 strain of current global
concern has not reached the United States, neither in poultry, wild fowl, nor humans. To
reduce this possibility, the U.S. Department of Agriculture (USDA) has blocked imports
of poultry and poultry products from affected countries, and increased smuggling
interdiction efforts. The Department of Homeland Security helps with enforcement.
Since wild birds can carry the disease, USDA and the Department of the Interior
have increased wild bird surveillance where flyways overlap because officials suspect
migrating birds in Asia could carry the virus to Alaska, and down North American
flyways in the fall of 2006. However, USDA’s Office of Inspector General identified
gaps in the surveillance plan.4 Steps have been taken subsequently to improve
In August 2006, USDA confirmed that two wild mute swans in Michigan tested
positive for a low pathogenicity strain of H5N1. The swans showed no signs of sickness
and were tested as part of the expanded surveillance program. This LPAI strain does not
threaten poultry or humans like highly pathogenic H5N1, and is not in commercial flocks.
Congressional Hearings. The House and Senate agriculture committees held
hearings on avian influenza on November 16 and 17, 2005, respectively. Administration,
industry, and academic witnesses reviewed prevention and control efforts. The Senate
committee held another hearing to review avian flu preparedness on May 11, 2006.5
In the Rest of the World.6 Since December 2003, at least 10 Asian countries
have had confirmed outbreaks of highly pathogenic H5N1 in poultry. In 2005, the virus
spread westward towards eastern Europe, being confirmed in six new countries. In 2006,
it spread to dozens of new countries in Europe, the Middle East, and Africa.
See the U.S. Department of Agriculture (USDA) at [http://www.usda.gov/birdflu],and the
Centers for Disease Control and Prevention (CDC) at [http://www.cdc.gov/flu/avian].
USDA-OIG, Animal and Plant Health Inspection Service Oversight of Avian Influenza (Audit
Report 33099-11-Hy), June 2006 [http://www.usda.gov/oig/webdocs/33099-11-HY.pdf].
House Agriculture Committee, “Review Issues Related to the Prevention, Detection, and
Eradication of Avian Influenza,” Serial No. 109-21, November 16, 2005. Senate Agriculture
Committee, Avian Influenza: Role of U.S. Agriculture to Control and Eradicate, November 17,
2005; and USDA Avian Influenza Plan Review, May 11, 2006.
For international issues, see the World Health Organization (WHO) [http://www.who.int/en],
U.N. Food and Agriculture Organization (FAO) [http://www.fao.org], and the World
Organization for Animal Health (OIE) [http://www.oie.int].
The H5N1 outbreak is historically unprecedented and extremely challenging. The
U.N. Food and Agriculture Organization (FAO) estimates that over 200 million birds have
died or been culled. Some countries were reluctant to acknowledge the disease for fear
of economic consequences. In other countries, lack of compensation for farmers whose
flocks are destroyed has been a disincentive to report outbreaks early.
International Control Efforts.7 As H5N1 spreads, it may become endemic in
countries with low levels of veterinary services or animal husbandry practices that harbor
the virus. Chances increase that the virus will evolve through mutation or reassortment
into a strain that could be transmitted easily between humans. Thus, FAO and the World
Health Organization (WHO) developed a strategy calling for the swift and coordinated
control of avian flu in poultry as the best way to prevent or delay a human pandemic from
developing, by reducing the number of animal hosts in which the virus may evolve.
Wild birds are the primary natural reservoir for Influenza A viruses and often are
resistant to the virus. Domestic flocks can be infected by contact with wild birds. Avian
flu is highly contagious in domestic poultry. The virus is spread by contact with infected
feces, nasal, or eye excretions. People, clothing, vehicles, and supplies can carry the
virus between farms. Thus, strict biosecurity measures are adopted by nearly all U.S.
commercial poultry farms.8 Confined poultry sheds prevent contact with wild birds.
Avian flu viruses have been common in live bird markets. These markets sell less
than 1% of U.S. poultry, but outbreaks concern commercial growers who practice tighter
biosecurity. USDA has focused on these markets because insufficient biosecurity allowed
birds and equipment to intermingle at the market and return to farms. In Asia, a large
network of live bird markets and backyard farms have made eradication difficult.
Human Infection.9 Certain avian flu strains, including H5N1, can infect humans
through close poultry-to-human transmission, usually through with fecal matter or other
live bird excretions in backyard settings or home slaughtering. However, the species
barrier is significant. The human disease caused by H5N1 causes rapid deterioration and
fatality from viral pneumonia and organ failure. Officials worry that the virus could
mutate or combine with human flu viruses to allow efficient human transmission.
Food Safety. No epidemiological evidence exists indicating that people have been
infected with any avian flu virus, including H5N1, from properly cooked poultry or eggs.
“A Global Strategy for the Progressive Control of Highly Pathogenic Avian Influenza (HPAI),”
FAO and OIE, in cooperation with WHO, November 2005 [http://www.fao.org/ag/againfo/
subjects/documents/ai/HPAIGlobalStrategy31Oct05.pdf], and “Avian Influenza Control and
Eradication: FAO’s Proposal for a Global Programme,” FAO, Jan. 2006 [http://www.fao.org/ag/
againfo/subjects/documents/ai/Global_Programme_Jan06.pdf]. See also CRS Report RL33219,
U.S. and International Responses to the Global Spread of Avian Flu: Issues for Congress.
For biosecurity recommendations, see the USDA “Biosecurity for the Birds” website at
For more on human issues, see CRS Report RL33145, Pandemic Influenza: Domestic
Preparedness Efforts, by Sarah A. Lister.
The virus is killed at conventional cooking temperatures (160 degrees F), making properly
cooked poultry safe. However, highly pathogenic viruses such as H5N1 can spread to
nearly all parts of an infected bird, survive in raw poultry, and be spread if contaminated
poultry is marketed and prepared.10 Yet, with commercial poultry production under strict
veterinary control, such as in the United States, infected poultry are very unlikely to enter
the food chain. Infected flocks are destroyed and not slaughtered for food. Thus, the
Centers for Disease Control and Prevention (CDC) and the USDA recommend standard
food safety practices such as those for preventing infection from Salmonella and E.coli.11
Avian flu is controlled domestically through prevention and eradication by individual
farmers cooperating with industry associations and state and federal governments. The
USDA Animal and Plant Health Inspection Service (APHIS) is the lead federal agency.
Internationally, FAO has a joint response plan with WHO for the current outbreak.
Preventing Infection. Biosecurity practices are the most important means of
preventing outbreaks in poultry. This includes preventing access of wild birds to
domestic flocks and limiting access to farm buildings. For example, delivery trucks and
personnel are cleaned and disinfected before entering a farm’s biosecure area. In other
parts of the world, small farms or backyard flocks without biosecurity practices have
posed greater problems for control. Such animal husbandry practices are slow to change.
Vaccines. While vaccination of poultry is possible and has been used on a small
scale with some success, it generally is not considered a sufficient control method.
Vaccination poses problems for international trade as many countries will not import
poultry products from other countries that use vaccination, since animals will test positive
for antibodies. If vaccination is not administered and monitored correctly, it can allow
the virus to become endemic and continue to spread or mutate.12
In the United States, vaccination is most likely to be used for breeding poultry, egg
layers, and other higher value birds. Vaccination in a ring surrounding an eradication
zone is another possible vaccination strategy.
WHO, “Avian Influenza (AI): Food Safety Prevention Measures”, accessed May 3, 2006 at
“Highly Pathogenic H5N1 Avian Influenza Outbreaks: Food Safety Implications,” Nov. 4, 2005,
USDA Fact Sheet, “Avian Influenza,” March 2006, [http://www.usda.gov/wps/portal/
Savill et al., “Silent spread of H5N1 in vaccinated poultry,” Nature, 442: 17 (August 2006),
p. 757, at [http://www.nature.com/nature/journal/v442/n7104/pdf/442757a.pdf]. Capua and
Marangon, “Vaccination for avian influenza in Asia,” Vaccine, 22 (2004), 4137-7138, at
[http://www.oie.int/eng/avian_influenza/vaccination%20in%20Asia.pdf], and Capua and
Marangon, “The use of vaccination as an option for the control of avian influenza,” May 2003,
In November 2005, USDA had a stockpile of 40 million doses of vaccine (for two
types of H5 and two types of H7 viruses). USDA plans to double this stockpile with
supplemental funds appropriated for avian flu in December 2005 (discussed below).
Eradicating Outbreaks. Because the virus is highly contagious and easily spread
in poultry, the most common method of control after there is an outbreak is culling (also
called “stamping out,” or depopulating) the infected flocks, and certain flocks in close
proximity to the infected flock. Following depopulation, buildings and equipment are
rigorously disinfected before new birds are allowed, a process that takes at least several
weeks. The virus is killed by common disinfectants or heat (about 160 degrees F).
Domestic outbreaks usually are managed through joint federal, state, and industry
cooperation. States usually lead the response in terms of depopulation and quarantines
of surrounding areas which are imposed until the disease is eradicated. APHIS provides
personnel and equipment to advise and supplement state resources. In highly pathogenic
outbreaks, APHIS may take a larger role. Federal statute allows the destruction of
affected animals (9 CFR 53.4). The USDA National Veterinary Services Lab (NVSL)
conducts confirmatory tests on the pathogenicity and type of virus. USDA also works to
limit export restrictions (such as to states or counties) and reopen export markets.
Indemnities to Farmers. Compensation programs are desired to encourage
farmers to report outbreaks and cooperate with control programs when culling is needed.
States generally manage indemnification programs for low pathogenicity outbreaks.
Some industry associations, such as those on the Delmarva peninsula (Delaware,
Maryland, and Virginia), have compensation funds. In the past, USDA has not had a
compensation program for LPAI.13 However, a new low pathogenicity indemnification
program was begun in FY2005 and final regulations are expected in 2006. USDA’s
standard indemnification rate for low pathogenicity programs is 50% of fair market value,
which may supplement state or industry compensation. For highly pathogenic outbreaks,
regulation allows USDA to offer 100% indemnification (9 CFR 53.2).
Federal Appropriations to Control Avian Flu in Poultry
For FY2007, USDA requests $82 million for avian flu: $77 million for APHIS and
$5.4 million for agricultural research. Of the amount for APHIS, $56.7 million would be
for a new HPAI monitoring and surveillance program, and $16.7 million for LPAI. The
Senate-reported appropriations bill (H.R. 5384) concurs with the HPAI request, but
provides $3 million less for LPAI. The House-passed bill concurs with the LPAI request,
but provides $9.5 million less than requested for HPAI.
For FY2006, the regular appropriation to APHIS for its LPAI program is $13.8
million (but with carryover, $28.3 million is available, with about $12 million for
indemnities; P.L. 109-97, H.Rept. 109-255). In addition, Congress appropriated USDA
$91.4 million in emergency supplemental funds as part of $3.8 billion for pandemic
influenza (Division B, Title II, of P.L. 109-148). From the supplemental, APHIS received
$71.5 million for domestic surveillance, diagnosis, and vaccine stockpiles; and
international technical assistance for surveillance, biosecurity, and control.
A limited indemnification program was created for an LPAI outbreak in 2002 (9 CFR 53.11).
In FY2005, Congress appropriated APHIS $23.8 million for avian flu, with about
half for the indemnity reserve. In FY2004, APHIS received a $1 million appropriation,
and USDA transferred $13.7 million in emergency funds during the 2004 outbreak.
In other international, agricultural aid, the Emergency Supplemental Appropriations
Act of 2005 (P.L. 109-13) provided $25 million to the U.S. Agency for International
Development (USAID) and CDC to combat avian flu. Conferees encourage cooperation
with FAO and WHO on a joint international plan (footnote 6).
Avian flu can affect the agricultural economy significantly. Usually, direct costs
include culling birds and quarantining farms. Larger economic effects arise from
international trade bans which affect farms outside the quarantine area. However, in the
current H5N1 outbreak, global consumer confidence is increasingly at stake despite
official statements that normal cooking would kill any virus if it was present.
With strong consumer confidence, demand for healthy poultry may rise. But weak
consumer confidence could depress poultry prices and raise demand for substitute meats.
In a recent domestic survey, 46% of chicken eaters said they would stop eating chicken
and 25% said they would eat less chicken if avian flu entered the United States.14 In 2006,
consumer demand for poultry dropped in Europe and Africa. Lower shipments to Eastern
Europe and Central Asia depressed U.S. poultry prices in 2005.15
Demand for feed such as corn and soy meal is tied to poultry production. Poultry
account for about one-third of total world feed use. So far, the global impact on feed
consumption has been limited due to relatively quick recovery of production where
outbreaks were contained, since the production cycle is quite short (about eight weeks).
The United States is the world’s largest producer and exporter of poultry meat and
the second-largest egg producer. About 8.5 billion broilers are produced, worth over
$23.3 billion on the farm (22% of farm livestock sales, and 12% of total farm sales
including crops). Broiler production accounts for about $15 billion, eggs $5 billion, and
turkeys nearly $3 billion. Five states account for 60% of U.S. production: Georgia (15%),
Arkansas (14%), Alabama (13%), Mississippi (9%), and North Carolina (9%). About
16% of U.S. poultry production is exported.
No economic estimates of an H5N1 outbreak in the United States are provided
because the extent of such an outbreak is highly uncertain.
Harvard School of Public Health, “Project on the Public and Biological Security,” January 1725, 2006, [http://www.hsph.harvard.edu/press/releases/press02232006.html].
FAO, “Escalating bird flu crisis jeopardizes global poultry trade prospects,” Feb. 28, 2006
[http://www.fao.org/newsroom/en/news/2006/1000240/index.html], and USDA Economic
Research Service, “Livestock, Dairy, and Poultry Outlook,” February 15, 2006 (monthly),