The Lancet Infectious Diseases 2006; 6:185
Avian influenza goes global, but don't blame the birds
Since early 2006, highly pathogenic avian influenza H5N1 has been
clocking up air miles at an alarming rate. It has spread quickly to
Europe, the middle east, India, and Africa following no apparent pattern,
and underlining how little scientists know about the virus ecology
and where it will strike next. There is now growing concern that the
whirlwind spread of avian flu in some parts of the world is not entirely
governed by nature, but by the human activities of commerce and trade.
Since mid-2005, the Food and Agriculture Organisation (FAO) and WHO
have given wide prominence to the theory that migratory birds are carrying
the H5N1 virus and infecting poultry flocks in areas that lie along
their migratory route. Indeed, this is probably how the virus reached
Europe. Unusually cold weather in the wetlands near the Black Sea,
where the disease is now entrenched, drove migrating birds, notably
swans, much further west than usual. But despite extensive testing
of wild birds for the disease, scientists have only rarely identified
live birds carrying bird flu in a highly pathogenic form, suggesting
these birds are not efficient vectors of the virus. Furthermore, the
geographic spread of the disease does not correlate with migratory
routes and seasons. The pattern of outbreaks follows major road and
rail routes, not flyways.
Far more likely to be perpetuating the spread of the virus is the
movement of poultry, poultry products, or infected material from poultry
farms-eg, animal feed and manure. But this mode of transmission has
been down-played by international agencies, who admit that migratory
birds are an easy target since nobody is to blame. However, GRAIN,
an international, non-governmental organisation that promotes the sustainable
management and use of agricultural biodiversity, recently launched
a critical report titled Fowl play: the poultry industry's central
role in the bird flu crisis. GRAIN points a finger at the transnational
poultry industry as fuelling the epidemic. Over the years, large concentrations
of (presumably stressed) birds have facilitated an increased affinity
of the virus to chickens and other domestic poultry, with an increase
in pathogenicity. Since the 1980s, the intensification of chicken production
in eastern Asia has gained momentum, changing the whole dynamic of
avian influenza viruses in the southern China epicentre, which has
had far-reaching consequences for the rest of the world.
Reports suggest that the outbreak in Nigeria emerged as a result of
illegally imported poultry, specifically day-old chicks. It seems that
Nigeria has continued to import chickens from China and Turkey despite
the FAO forbidding such trade with infected countries. It is unacceptable
that this trade continues unchecked. Tighter regulation and monitoring
of poultry movement should be enforced, and the perpetrators held accountable
for their actions.
Of major concern now is the continued spread of the H5N1 virus in
Africa, where millions of people live alongside chickens, increasing
the chances of the virus crossing into human beings. Poor medical,
veterinary, and laboratory services, lack of health education, porous
borders, and high mortality rates from other infectious diseases mean
a new human influenza virus could spread undetected. Furthermore, we
do not know what the impact of exposure to avian influenza will be
on the many people who are already immunocompromised with, for example,
As in southeast
Asia, poultry culls in Africa would damage the livelihood of millions
Poultry is a major source of dietary protein,
thus ridding the continent of H5N1 could lead to malnutrition with
devastating consequences to human health. Even with a concerted education
campaign about the dangers of contact with dead birds, many Africans
are likely to continue selling or eating birds that have died because
they cannot afford to throw away meat even if it might be infected.
Africa will need financial assistance to combat bird flu. Currently
the $1·9 billion pledged in Beijing in January to combat avian
influenza is earmarked for aiding research efforts, strengthening surveillance,
and increasing the stockpiling of surgical masks and other equipment.
But some of these funds should be set aside to compensate African farmers
for destruction of their birds. Inadequate compensation will not only
tip people into extreme poverty, but will also help spread the virus
by discouraging people from reporting the disease.
As bird flu spreads it is clear no country is protected from the virus.
Although the risk to people is still low, movement of the virus through
more hosts and different environments increases the chances of viral
mutation and efficient transmission among human beings.
The Lancet Infectious Diseases