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25 Jan 2006

A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases

Date: Wed 25 Jan 2006
From: ProMED-mail <>
Source: Reuters Alertnet, 24 Jan 2006 [edited]

Wild birds: vectors or victims of avian flu?
- -----------------------------------------------
Do the wild birds that fly through cold winter skies to warmer lands
silently carry deadly bird flu around the world, or, asks this story, are
they simply potential victims?

The story says that many scientists believe migrating wild fowl are
responsible for carrying the virus from Asia and Siberia to Romania and
Turkey. And although some argue there is not enough evidence yet for firm
conclusions, the theory is gaining ground.

The World Health Organization was quoted as saying in its latest bird flu
fact sheet last week [3rd week December 2006] that, "Scientists are
increasingly convinced that at least some migratory waterfowl are now
carrying the H5N1 virus in its highly pathogenic form, sometimes over long
distances, and introducing the virus to poultry flocks in areas that lie
along their migratory routes," and that scientists found that viruses from
the most recently affected countries, all of which lie along migratory
routes, were almost identical to viruses recovered from dead migratory
birds at Qinghai Lake in China. The viruses from Turkey's 1st human cases
were also virtually identical to the Qinghai Lake strain, it added.

Juan Lubroth, the senior officer for infectious diseases with the United
Nations Food and Agriculture Organization (FAO), was quoted as telling
Reuters that, "We do know that avian influenza viruses are carried by
migratory birds all over the world. But not all of them are highly
pathogenic or H5N1. I think that wild birds may introduce the virus, but it
is through man and man's marketing systems (the poultry trade) that the
disease spreads. It is also possible that poultry can transmit the virus to
wildlife when they share the same ecosystem."

The story goes on to say that the growing popularity of the migratory bird
theory has worried an increasingly vocal group of conservationists who fear
unfounded claims could lead to indiscriminate slaughters.

Dr. Richard Thomas of BirdLife International was quoted as telling Reuters
that, "The pattern of outbreaks between Asia and eastern Europe do not
follow any known pathway for migrant birds, which tend to fly on
northerly-southerly routes. They don't go east-west."

Andre Farrar, an ornithologist with Britain's Royal Society for the
Protection of Birds (RSPB), was cited as saying that if migratory birds
were spreading H5N1, it would have been spotted elsewhere, adding, "Go back
a stage and start off in southeast Asia. If migration was the primary
route, you would have expected it in Australasia, but it hasn't shown up
there. There is clearly a theoretical risk that migrant birds can carry
bird flu. There is published work showing that ducks in captivity can
survive H5N1 infection and can shed the virus, and we'd be foolish to
ignore this."

[Byline: Ed Stoddard]

- --

Date: Wed 24 Jan 2006
From: ProMED-mail <>
Source: Reuters via The, 24 Jan 2006 [edited]

Frosts drive birds to Turkey from Ukraine
- -----------------------------------------------
Ukraine's agriculture ministry was cited as saying in a statement on
Tuesday [24 Jan 2006] that severe frosts in Ukraine's southern Crimea
peninsula have prompted migratory birds to leave the area for Turkey,
lowering the risks of new domestic outbreaks of bird flu, adding, "A large
number of migratory birds which traditionally winter in Crimea have left
the region for Turkey. This could greatly improve the epizootic situation
in southern Ukraine."

Ukrainian officials have detected bird flu in 23 Crimean districts so far.
Testing showed the cases involved the deadly H5N1 strain of the disease.

- --

Date: Wed 25 Jan 2006
From: ProMED-mail <>
Source: OIE Disease Information, 19 Jan 2006, 19(3) [edited]

Highly Pathogenic Avian Influenza In Croatia
- -----------------------------------------------
Follow-up report No. 4. See also:
<> 16 Dec 2005,
<> 28 Oct 2005,
<> 28 Oct 2005,
<> 28 Oct 2005.

Information received on 19 Jan 2006 from Dr. Mate Brstilo, Director of the
Veterinary Administration, Ministry of Agriculture and Forestry, Zagreb:

End of previous report period: 13 Dec 2005 (see Disease Information, 18
[50], 512, dated 16 Dec 2005).

End of this report period: 17 Jan 2006.

Identification of agent: highly pathogenic avian influenza virus serotype H5N1.

Date of 1st confirmation of the event: 21 Oct 2005.

Date of start of the event: 19 Oct 2005.

Clinical disease: yes.

Nature of diagnosis: laboratory.

During regular monitoring activities conducted at Ribnjak 1905 fish pond, 4
swans in a flock of around 265 swans were shot for diagnostic purposes;
samples were taken and sent to the Poultry Center of the Croatian
Veterinary Institute in Zagreb. Laboratory testing revealed that 2 samples
were positive for avian influenza virus. All samples were found to be
negative on virus isolation in chicken embryos.

In the same location, 26 other birds (wild ducks) were shot for diagnostic
purposes. Samples from these 26 birds were tested at the Poultry Center of
the Croatian Veterinary Institute in Zagreb and were all found to be
negative for avian influenza.

Details of outbreak:
1st administrative division (County): Osijecko-Baranjska
Lower administrative division (municipality): Nasice
Type of epidemiological unit: village
Name of the location: Ribnjak 1905
Latitude: 45o 34' 020" N; Longitude: 18o 08' 891" E
Start of the outbreak: 3 Jan 2006
Species: fau
Number of animals in the outbreak
susceptible / cases / deaths / destroyed / slaughtered
265 / ... / 0 / 4 / 0

Laboratory where diagnostic tests were performed: Poultry Center of the
Croatian Veterinary Institute, Zagreb
Date: 13 Jan 2006
Birds examined: 4 swans
Diagnostic tests used:
1. virus isolation in chicken embryos. Results: negative.
2. hemagglutination inhibition test. Results: positive (2 out of 4 swans).
Date: 17 Jan 2006
Birds examined: 26 wild ducks
Diagnostic tests used:
1. virus isolation in chicken embryos. Results: negative.
2. hemagglutination inhibition test. Results: negative.

Source of outbreak or origin of infection: seasonal migration of wild
birds: swans.

- --

[Though the sequencing data from the Russian labs -- regarding isolates
from wild birds (see 20060120.0191) -- are persuasive, it is still far from
proven that bird migration is a significant factor in the spread of H5N1
virus infection of domestic poultry. The sequence data lack a temporal
scale, which would confirm the direction of movement of the infection.
Wider surveillance is necessary, including samples taken from birds at
different times and from sites at intermediate points on migration routes
and also outside the current range of HPAI H5N1. - Mod.CP]

[The chapter "Role of Migratory Birds" in the recent overview "H5N1
Outbreaks and Enzootic Influenza" by Robert G. Webster, Malik Peiris,
Honglin Chen and Yi Guan may be helpful in further elucidating the issue.
(From: Emerging Infectious Diseases, 12 [1], Jan 2006,

"Role of Migratory Birds: Migratory waterfowl are generally believed to be
the main reservoir of all 16 subtypes of influenza A viruses, including H5
and H7 subtypes. However, less agreement is found regarding the role of
migratory waterfowl in the initial spread of highly pathogenic H5N1 viruses
across eastern Asia in 2003. The isolation of highly pathogenic H5N1 from
herons, egrets, and peregrine falcons in Hong Kong in 2003 and 2004 leaves
no doubt that wild migratory birds can be infected and may spread disease
to local poultry flocks. The outbreak in Qinghai Lake proves that these
highly pathogenic H5N1 influenza viruses are transmissible among migratory
waterfowl. The migration route of shorebirds in the east Asian-Australasian
flyway does overlap the areas that have had H5N1 outbreaks, although the
virus has been notably absent in Taiwan, Malaysia (except for occasional
outbreaks near the Thai border), and western Australia. The role of
migratory birds in the transmission and spread of highly pathogenic H5N1
viruses is still unclear. However, the recent outbreak of H5N1 infection in
bar-headed geese and other species in Qinghai Lake is a cause for concern,
because these birds migrate southward to the Indian subcontinent, an area
that has apparently not been affected by H5N1 avian influenza. If the virus
were to become entrenched in India, its geographic range would be
substantially extended, and the pandemic threat would increase accordingly.
A mutation in the PB2 gene (residue E627K) associated with pathogenicity in
mammals has been found in viruses isolated from birds in Qinghai Lake; this
finding has caused concern that this mutation will be transferred to other
migratory birds (e.g., wild ducks) and will be spread because not all
infected birds die.

Although culling domestic poultry to contain the spread of highly
pathogenic H5N1 virus is considered an acceptable agricultural practice,
culling migratory birds is not acceptable to any international authority
(Food and Agriculture Organization of the United Nations [FAO], the World
Organisation for Animal Health [OIE], the World Health Organization [WHO]).
The idea of culling migratory birds must be strongly discouraged, for it
could have unknown ecological consequences. Instead, since highly
pathogenic H5N1 has been demonstrated in migratory birds, the poultry
industries of the world must adapt measures, such as increased biosecurity,
the use of vaccines, or both."

The said overview might have been written prior to the westward spread of
H5N1 and its detection in Romania, Turkey, Crimea and Croatia. This does
not affect the validity of the authors' remarks, discouraging culling of
migratory birds while underlining the measures to be adapted.

The OIE report on the identification of H5N1 in swans in Croatia, a country
where -- reportedly -- no disease has been detected in domestic poultry,
adds another perspective; information on the possible origin of these
swans, allegedly "seasonal migrants," will help. The virus has been
isolated there, since 19 Oct 2005, from sick and healthy swans in 2
locations ("Grudnjak" fishpond in the village Zdenci, 45:34:45N, 17:56:44E,
and "Ribnjak" fishpond in the village Nasice, 45:29:07N, 18:05:52E; the
distance between the 2 is about 20 km). The 1st isolates were sent to the
reference centre for avian influenza, VLA Weybridge, which reported on 26
Oct 2005 the following:

"Conventional amino acid sequencing at the cleavage site of the
hemagglutinin (HA) has revealed multi basic amino acid sequences of
PQGERRRKKRGLF' which is consistent with highly pathogenic avian influenza.
Molecular phylogeny based on a short fragment (300 base pairs) of HA1
indicates that the HA gene of all the 4 samples has a 99.7 percent identity
with A/Great Black Headed Gull/Qinqhai/2/05, 99.3 percent identity with the
Turkish virus and 99.1 percent identity with the Romanian virus."

Croatia's reports can be accessed in OIE's Update On Avian Influenza In
Animals (Type H5), available at
< percent20INFLUENZA/A_AI-Asia.htm>.
  - Mod.AS]

[see also:
Avian influenza - Eurasia (02): Ukraine (Crimea), 20060105.0037
Avian influenza - Eurasia (04): Turkey, wild ducks, suspected 20060106.0047
Avian influenza - Eurasia (05): China (Sichuan), wild birds 20060107.0053
Avian influenza - Eurasia (17): Russia 20060112.0112
Avian influenza - Eurasia (21): prevention, surveillance wild birds
Avian influenza - Eurasia (27): Russia, wild birds 20060120.0191
Avian influenza - Eurasia (31): Ukraine (Crimea), wild birds 20060123.0229
- ----
Avian influenza - Eurasia (106): Denmark, wild bir... 20051221.3650
Avian influenza - Eurasia (45): Finland, avian spp. 20051101.3191
Avian influenza - Eurasia (49): wild birds 20051103.3211
Avian influenza - Eurasia (52): Romania, migratory... 20051106.3247
Avian influenza - worldwide (03): FAO Update 20051106.3251
Avian influenza - Eurasia (58): wild birds, Italy,... 20051110.3286
Avian influenza - Eurasia (61): wild ducks, Italy,... 20051112.3318
Avian influenza - Canada (02): survey wild ducks 20051102.3204]


End of ProMED Digest V2006 #41