Although the recent spread of the H5N1 strain of avian influenza
to Nigeria and
several countries in the EU is causing public concern about its potential
to reach
Australia, it should be reiterated that the situation with regards to Australia
has not
changed. The westward spread of H5N1 into Europe is associated with Anseriformes
(ducks, geese and swans), which do not migrate to Australia. However, because
of the
possibility that migrating waterbirds are assisting the spread of the disease,
Birds
Australia is keeping a watching brief on developments overseas as well
as working
with Australian Government Health and Agriculture Departments to monitor
the
situation in Australia.
The purpose of the following statement is to inform the public about the
extremely
low level of risk of migrating birds carrying the disease to Australia
and passing it to
humans, and to direct the public to other sources of information on avian
influenza.
The Current Outbreak of Avian Influenza Strain H5N1
The H5N1 virus is spreading, with outbreaks in China, Kazakhstan, Mongolia,
regions of Russia and countries around the Black Sea, and more recent appearances
in
Turkey, Romania, Slovenia, Greece, Italy, Austria, Germany, France and
Nigeria, on
top of the spread through Asia since the end of 2003. It is not yet entirely
clear how
the disease is spreading, but clearly there is a possibility that migrating
waterbirds
may be involved. Swans, in particular the Mute Swan Cygnus olor, have been
implicated in the spread of H5N1 into European countries.
The movement of swans into southern Europe is likely to be in response
to freezing
weather conditions around the Black Sea. Wild birds normally die within
a few days
of infection. The appearance of the swans in Italy, Slovenia and Greece
indicates they
were likely infected just prior to setting off on their journeys. It is
possible the swans
caught the disease from other wild birds, although this is unlikely given
the tens of
thousands of waterfowl that have tested negative for H5N1 over the last
decade. A
more likely route is through contact with infected poultry or their faeces.
Mute Swans,
like wild geese but unlike most ducks, often feed by grazing on agricultural
fields.
The practice of spreading poultry manure onto fields as fertiliser is widespread
in
many parts of Eastern Europe, and this is a possible source of infection.
The swan deaths highlight the need for implementation of strict biosecurity
measures
in infected areas, and also highlight the need for monitoring of healthy
wild birds for
the presence of the virus. Swans seem particularly susceptible to avian
influenza, and
swan deaths have previously been reported in Russia and in October 2005
in Croatia.
Tests on the Croatian swans found the birds excreted tiny amounts of the
virus. Even
so, it was remarkable that waterbirds sharing the same fish ponds as infected
swans
remained free of the disease.
The finding of dead swans will fuel the debate over how H5N1 is spreading.
However, it is notable that if wild birds had been spreading the disease
across
continents there would have been trails of dead birds following migration
routes,
which isn't the case. There is still no explanation as to why certain countries
on flight
paths of birds from Asia remain flu-free, whilst their neighbours suffer
repeated
infections, nor of why only a single strain of H5N1 is found in outbreaks
west of
China.
An outbreak of H5N1 was reported on a large commercial chicken farm in
the
northern state of Kaduna, Nigeria, in early February 2006. Unofficial reports
suggest
the virus is genetically related to the strain that spread from Qinghai,
China, west to
Turkey in 2005. This is the first reported outbreak of H5N1 in Africa,
and a serious
development in the continuing spread of avian flu. Initial, unconfirmed
reports
indicate that the virus may have infected chickens at other commercial
farms in the
area. It may have been present since 10th January, when chickens first
began dying,
but was earlier diagnosed as Newcastle disease. (It is possible that the
outbreak
involves both diseases). Outbreaks of H5N1 at commercial chicken farms
have
previously been reported in Asian countries, notably in Laos, where 42
of 45
outbreaks were confirmed on commercial enterprises.
Importation of infected poultry is a suspected source of the Nigerian outbreak.
In
2004, the government banned imports of live poultry, although in early
2005 it came
under pressure from the country’s farmers to resume them again because
the country
lacked the technology to produce sufficient quantities of day-old-chicks.
A 2003
United States Department of Agriculture report stated that prior to an
earlier 2002
import ban on poultry meat, "virtually all imported frozen poultry
entered Nigeria
illegally."
In 2005, BirdLife warned of the risk of H5N1 spreading through illegal
importation of
poultry and poultry products after live chickens from China were confiscated
by
Italian customs and tonnes of frozen Chinese poultry meat were seized in
the UK.
The following information is taken from the website of Birdlife International.
Birds
Australia is the Birdlife Partner in Australia and endorses the views expressed.
“There are numerous strains (at least 144) of avian influenza, many
of which
circulate in wild birds at low levels, but which can occur more frequently
in
waterbirds. Most of these viruses within wild bird populations are benign.
Highly
pathogenic-avian influenza viruses can cause great mortality in domestic
poultry
flocks but are very rare in wild birds. H5N1 is highly pathogenic but was
never
recorded in wild birds before the recent outbreaks in South-east Asia,
Russia and
countries around the Black Sea. It is likely that it originated in domestic
poultry
through mutation of low pathogenic sub-types and was subsequently passed
from
poultry to wild birds.
Transmission is promoted in domestic flocks due to the density of birds
and the
consequent close contact with faecal and other secretions through which
the virus
can be transmitted. Husbandry methods in South-east Asia where domestic
flocks
are often allowed to mix freely with wild birds, especially waterfowl will
have
facilitated the transmission to migratory waterbirds, leading to several
reported
instances of die-offs.
There is no evidence that H5N1 infection in humans have been acquired from
wild
birds. Human infections have occurred in people who have been closely
associated with poultry. The risk to human health from wild birds is extremely
low
and can be minimised by avoiding contact with sick or dead birds. However,
there
is a possibility that this virus could develop into one that might be transmitted
from human to human. If this happens, then it is most likely to happen
in Southeast
Asia, from where it could then spread rapidly around the world.
The situation is evolving rapidly from day to day, and our position on
the disease
and proposed control measures will continue to evolve as new data emerge.
The
points below are based on the best information available on 21 February
2006:
1. The most recent outbreaks suggest that migratory birds may have
transmitted the disease between countries or regions. Although this link
has not been proven we cannot ignore the possibility. Movements of
domestic poultry, another possible transmission route, have been largely
implicated in the spread of the disease in SE Asia.
2. There have been no recorded instances of transmission of the disease
between infected wild birds and humans. The H5N1 virus strain is not
currently contagious between humans and most human cases to date have
been associated with close contact with infected domestic poultry. The
risk
of a human contracting the disease from a wild bird is remote, unless
there was excessive close contact with infected birds and their excreta.
3. Culls of wild birds are highly unlikely to stop the spread of the disease
and
are extremely difficult to implement. This view is shared by the World
Health Organization, Food and Agriculture Organization of the United
Nations, the World Organisation for Animal Health and the UK
Government. Indeed, culls have the potential to make the situation worse
by dispersing infected individuals and stressing healthy birds, making
them more prone to disease. Moreover, it would divert resources away
from important disease control measures.
4. The most efficient control techniques involve improved biosecurity,
primarily of the poultry industry, to reduce the likelihood of contact
between domestic stock and wild birds or infected water sources. This
needs to be coupled with swift and complete culls of infected poultry flocks
in the event of an outbreak. Further measures that should be considered
include stricter controls on wild bird markets, and movements of domestic
poultry. Such measures should be introduced worldwide. Countries
currently free of the disease should consider a ban on imports of domestic
poultry and wild birds for the pet trade from affected regions. Preventing
public access to infected sites is also clearly a sensible precaution.
5. It is important that discussions of the issues relating to avian influenza
should differentiate between the real problems caused by the spread of
the disease within bird populations, especially within the poultry industry,
and the theoretical risks of a human pandemic, which might not happen.
6. We fully recognise the potential for a human pandemic should the current
viral strain increase its transmissibility through mutation or reassortment,
thus facilitating human to human transfer of the disease, and in the
absence of swift measures to safeguard public health. We also recognise
the impact the current strain is having on local economies forced into
culls
of domestic flocks, and the potential for greater financial impact on the
poultry industry.
7. In addition to the impact of the disease on economics and livelihoods,
and
the potential impacts for human health, there are also potential
implications for conservation. For instance, it is estimated that somewhere
between 5% and 10% of the world population of the Bar-headed Goose
Anser indicus perished in the recent outbreak in China.
Notes:
The World Heath Organization (WHO), The Office International des Epizooties
(OIE) and the Food and Agriculture Organization (FAO) all concur that “the
control of avian influenza infection in wild bird populations is not feasible
and
should not be attempted.”
The Risk of Migrating Birds Bringing Avian Influenza to Australia
Various strains of avian influenza are present in birds in Australia but
these are
largely benign. The current concern is over the specific strain called
H5N1.
Each year over 3 million migrating shorebirds spend the southern summer
in
Australia. These birds have come from breeding grounds as far away as Siberia
and
Alaska and travel to Australia along the East-Asian/Australian Flyway.
This
migration pathway takes the birds through east and South-east Asian countries
where
the H5N1 strain is present. However, while it is possible migrating birds
could carry
highly pathogenic forms of avian influenza to Australia, it is unlikely
for the
following reasons:
1. Monitoring data from northwest Australian over the past 25 years suggest
the
incidence of avian diseases (including influenza, encephalitis and Newcastle
disease) in migratory shorebirds is low. No birds with the H5N1 strain
of
avian influenza have ever been found in Australia including during the
present
time.
2. The birds possibly associated with the spread of avian influenza in
Asia and
Europe are migrating waterfowl such as swans, ducks and geese. In Australia,
such species are not migratory, and there is probably only limited interaction
with birds to the immediate north of Australia, such as PNG. These areas
have
not reported any instance of avian influenza at the current time.
3. Migrating shorebirds travel relatively quickly from northern hemisphere
breeding grounds, covering the thousands of kilometres in a few long “steps”
(for some species, perhaps three or four steps) with brief rests in between.
The
limited time spent in countries affected by the current outbreak reduces
the
likelihood of contracting the disease. As the migration is highly demanding,
energetically speaking, it may be that diseased birds could not complete
the
migration to Australia anyway.
4. Many, and perhaps most, migrating shorebirds inhabit the inter-tidal
zone
during and after their migration, reducing the likelihood of contracting
the
disease from waterfowl and poultry, or the likelihood of transmitting the
disease to these species on arrival in Australia.
Could H5N1 Avian Influenza Reach Australia?
The most credible ways for avian influenza to reach Australia are through
the
importation of infected live birds, or of poultry products. Both of these
pathways are
under the strict control of the Australian Quarantine and Inspection Service,
but a
residual risk of accidental introduction remains.
In the event that the H5N1 strain develops the capability for human-to-human
transfer
the major risk of entry to Australia would be posed by international travellers.
What Should I do if I am in Direct Contact with Migratory Birds?
Although the risk of contracting avian influenza from wild birds in Australia
is very
low there are some sensible precautions which people can take:
¨ Don’t pick up sick birds or dead birds,
¨ When walking, keep your dog on a lead at all times to avoid contact
with dead
or injured birds,
¨ If you have ducks or chickens, don’t let wild birds mix with
them.
¨ Observe wild birds from a distance.
¨ Avoid touching wildlife – if there is contact, do not rub eyes,
eat drink or
smoke before washing hands thoroughly.
What is Birds Australia Doing?
Birds Australia is directly monitoring the international situation as the
outbreak
unfolds. Our colleagues at Birdlife International and Wetlands International
are
assisting by providing us with information.
We are cooperating with the Australian Government Departments of Health
and
Ageing, and Agriculture Fisheries and Forestry, who in turn have international
links
through the World Health Organisation (WHO), the World Organisation for
Animal
Health (OIE) and the Food and Agriculture Organization (FAO).
Birds Australia’s vast datasets are being used by authorities to
examine areas where
migratory birds might occur near poultry facilities. This planning will
aid Australia’s
preparedness. Birds Australia is also assisting with surveillance, and
in understanding
the ecology of migratory and resident wild birds. Thus, we are contributing
to longerterm
solutions of this problem.
In 2004, Birds Australia’s journal, The Emu, published a review of
the role of wild
birds in the possible transmission of avian influenza.
Useful links
Australia
Australian
Government Department of Agriculture Fisheries and Forestry:
Australian
Government Department of Health and Aging:
International
World
Health Organisation:
Food
and Agriculture Organisation:
World Organisation
for Animal Health (OIE)
Birdlife International:
(USA) Centers for Disease Control and Prevention:
Last updated 21 February 2006
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