Foie gras vector for H5N1?

From ANIMAL PEOPLE, July/August 2006:

WASHINGTON D.C.– The U.S. Department of Agriculture on June
29, 2006 released a draft summary of a $91 million battle plan to
combat any U.S. outbreaks of a “highly pathogenic avian influenza,”
such as the H5N1 strain that has killed more than 130 people
worldwide since 1996.
The plan discusses migratory bird surveillance, the
bird-breeding industry, poultry dealers, live-bird markets,
auctions and slaughterhouses, but appears to make no specific
reference to foie gras farming, a $25 million a year branch of
poultry production with just three major U.S. producers, whose farms
are concentrated in upstate New York and northern California.
The odds that H5N1 or any other deadly influenza might hit
the U.S. through foie gras farming may be incalculably low–but if
H5N1 begins killing human poultry workers in Europe, as it has since
2003 in Southeast Asia, experts suspect the lethal crossover might
begin on the sprawling foie gras farms of southwestern France and
parts of Hungary.

There are so far no known cases of H5N1 being transmitted
through consumption of foie gras, but the paste-like substance is
made from the macerated livers of artificially fattened ducks and
geese. As the livers of birds are among the body sites infected by
H5N1, Japan quickly banned imports of French-produced foie gras, as
well as all other French poultry products after H5N1 was found on a
French turkey farm in March 2006.
As Japan is not a large importer of most French poultry
products, the ban accounted for relatively little of a 50% drop in
French poultry exports during the next few weeks–a $130 million hit.
French exports within the European Union were protected somewhat
under protocols that quarantine producers by region rather than
nation, but 45 non-European Union nations suspended all poultry
imports from France.
However, the Japanese ban hit the foie gras industry hard.
Japan had imported approximately 10% of French foie gras production
in recent years.
The EU quarantine hit the foie gras industry too, as 22% of
French foie gras output is within Landes, the quarantined area.
Foie gras farmers were accordingly among the first French
poultry growers to vaccinate their flocks against H5N1, under
government orders.
Among those vaccinating were Benoit Descorps, of Horsarrieu,
and Eric Degert, of Clermont, witnessed by Associated Press writer
Elaine Ganley.
“Local officials deny that ducks were selected for vaccination simply
to protect luxury products like foie gras,” Ganley wrote.
“Veterinary teams are racing from farm to farm. They use a vaccine
against the H5N2 strain of bird flu, rather than H5N1, so that
laboratories can differentiate between vaccinated and infected ducks.”
The H5N2 vaccine also protects birds against H5N1.
“Non-vaccinated sentry ducks–50 to a flock of 500 to 3,000–serve as
a control group to flag contamination,” Ganley continued. “Breeders
say the alternative, keeping flocks indoors, is unworkable because
their free-range birds need to roam outdoors.”
Even in France, which produces 83% of the global foie gras
volume, and consumes 90%, foie gras farms are few compared to the
200,000 egg and broiler farms that account for 20% of the total
European Union egg and chicken output. The French foie gras industry
is worth $110 million, but the French egg and chicken industry is
worth $3.6 billion.
Yet the foie gras industry presents unique risks.
One of those risks is that domestic ducks and geese are much
more closely related than chickens to wild migratory waterfowl who
may bring H5N1 into a particular neighborhood. That means a virus
need not mutate as much to spread from a form carried by wild birds
to a form that attacks birds on foie gras farms–and potentially can
mutate from there to attack humans.
A second risk is that most European foie gras producers,
like those of Landes, still keep their flocks outdoors. Infection
from the wild is not considered the main route by which H5N1 spreads,
since most wild birds who become infected appear to die quickly,
close to domestic outbreaks. However, transmission by wild birds is
the H5N1 exposure route least susceptible to human control, and
migratory waterfowl are the birds believed to be most capable of
carrying H5N1 from farm to farm or region to region.

Unique risk

The greatest H5N1 risk associated with foie gras production,
however, is the method by which foie gras is made: ducks and geese
are induced to develop livers as much as six times their normal size
by having excessive rations of grain poured directly into their
gullets through a tube. This is done for anywhere from 10 to 30 days
preceding slaughter. The invasive and frequently violent aspects of
forced intubated feeding are the basis of humane opposition to the
foie gras industry.
Most laying hens and broiler fowl are handled by humans only
three times in their lives: when they are put into the cages or
enclosures where they spend most of their lives, when they are taken
out and stuffed into transport cages, and when they are killed.
Most chickens who fall ill die without any close-up human
examination or treatment. Except for carcass removal, they are not
handled at all. Poultry workers who wear gloves accordingly have no
direct physical contact with chickens who may be harboring a live
lethal virus.
Ducks and geese raised for foie gras, by contrast, are
handled or at least closely approached at least 20-30 times each,
mostly during the force-feeding. The process is semi-mechanized,
but not to the point of precluding all direct handling.
Because birds raised for foie gras are both potentially
exposed more to H5N1 from wild birds and have more opportunity to
infect humans, foie gras farms are potential incubators for mutant
forms of H5N1 that might easily cross into humans and then spread
from person to person.
Person-to-person transmission is believed to be an essential
development before H5N1 can become an authentic human epidemic, as
most humans do not have enough contact with poultry to be highly
exposed.
Although foie gras production is among the most
labor-intensive types of poultry farming, worker exposure is
geographically limited. Force-feeding birds for foie gras production
and/or sale is already banned in Britain, Denmark, Switzerland,
Finland, Norway, Sweden, Luxembourg, Germany, Poland, the Czech
Republic, and Israel.
The foie gras production bans substantially lower the risk
that foie gras could become a direct avenue for transmitting H5N1 to
the public, but a worker infected with a strain that passes from
human-to-human could become the source of an outbreak that might
radiate throughout Europe as rapidly as mass transportation can carry
anyone the worker comes into contact with before the disease is
identified.
H5N1 transmission to people, so far, requires more than
just casual contact with infected birds. Globally, most of the
130-plus known human victims have actually shared their homes with
poultry. Many, especially in Southeast Asia, have been
cockfighters. Some, most often in Turkey and Egypt, were children
who made pets of chickens or ducks.
Poultry barn workers, butchers, and feather-pluckers have
become ill chiefly when they did not wear gloves when handling birds.
Foie gras workers are not known to have contracted H5N1 yet,
though there is suspicion that China in particular has withheld
information about human cases lest public fear create civil unrest.
China is known to have a rapidly expanding foie gras
industry. China, the only nation in Asia with noteworthy foie gras
production, has had recurring H5N1 outbreaks in some of the same
areas, but whether foie gras farms have been involved is unclear
from the currently available information.
Partnering with the French firm Delpeyrat, a Chinese company
called the Jifa Group is currently force-feeding about 200,000 geese
in northeastern Jilin province, managing director Qi Mingce told
Agence France-Presse in April 2006, and plans to have about two
million geese by 2010.
Other Chinese foie gras producers reportedly now have about
100,000 ducks and geese, with expansion plans of their own.