CHOLERA, AVIAN - CANADA (NEWFOUNDLAND)
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A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail, a program of the
International Society for Infectious Diseases
<http://www.isid.org>

Date: 1 Feb 2007
From: ProMED-mail<promed@promedmail.org>
Source: CBC News [edited]
<http://www.cbc.ca/canada/newfoundland-labrador/story/2007/01/30/avian-cholera.html>


Avian cholera, a disease that can quickly kill bird populations, has been 
diagnosed in 6 dead seagulls, Newfoundland and Labrador's chief 
veterinarian reported Tuesday.

Hugh Whitney said the disease poses minimal risk to humans. He called on 
the public to avoid contact with birds they suspect may be infected with 
avian cholera.

However, the disease can cause what Whitney described as "large-scale 
die-offs in waterfowl and other bird populations."

Sick gulls have been reported at various offshore sites. As well, 
investigators are responding to reports of gull infections around the St. 
John's area, particularly at Quidi Vidi Lake in the city's east end.

Quidi Vidi Lake is a frequent stop for seagulls, and is near both a large 
landfill and the Atlantic Ocean.

Whitney advised the public to avoid contact with birds that may be 
infected, and to keep pets away. "The risk in contact with the sick or dead 
birds may include a skin infection if exposure is with an open cut," 
Whitney said in a statement.

The disease has so far been found in 3 gull species: great black-backed 
gulls, glaucous gulls and black-legged kittiwakes.

Avian cholera, a bacteria-based disease, can spread to other bird species, 
particularly scavengers such as crows, ravens and eagles.

"Affected birds may be seen lying on the ground, circling in the water with 
their heads twisting in different directions or found dead in areas where 
gulls roost," Whitney said. "Death is usually very quick."

Whitney called on poultry farmers to look after their stock and to try to 
keep gulls and scavengers from their premises.

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[A map of Newfoundland may be seen at 
<http://images.google.com/imgres?imgurl=http://www.reefball.com/map/newfoundland.gif&imgrefurl=http://www.reefball.com/map/newfoundland.htm&h=588&w=446&sz=31&tbnid=M8vITcpp5qPUTM:&tbnh=135&tbnw=102&prev=/images%3Fq%3Dmap%2Bof%2Bnewfoundland&start=1&sa=X&o>http://images.google.com/imgres?imgurl=http://www.reefball.com/map/newfoundland.gif&imgrefurl=http://www.reefball.com/map/newfoundland.htm&h=588&w=446&sz=31&tbnid=M8vITcpp5qPUTM:&tbnh=135&tbnw=102&prev=/images%3Fq%3Dmap%2Bof%2Bnewfoundland&start=1&sa=X&oi=images&ct=image&cd=1>

A discussion of Avian Cholera may be found in ProMED-mail posting 
200610231.3119.

Since avian cholera can kill quickly, it is not unusual to see a die-off of 
large number of birds quite suddenly. But seagulls are not one we often 
hear about.

A photo of a seagull may be seen at: 
<http://images.google.com/imgres?imgurl=http://www.mccullagh.org/db9/10d-16/assateague-seagull.jpg&imgrefurl=http://www.mccullagh.org/image/10d-16/assateague-seagull.html&h=512&w=768&sz=72&tbnid=fnEFT3QSbdph9M:&tbnh=95&tbnw=142&prev=/images%3Fq%3Dphoto%2Bof%2Bseagull&start=1&sa=X&oi=images&ct=image&cd=1> 
- Mod.TG]

[see also:
Cholera, avian - USA (CA)(03) 20070127.0355
Cholera, avian - USA (CA) (02) 20070117.0223
Cholera, avian - USA (CA) 20070112.0162
2006http://www.promedmail.org/pls/promed/f?p=2400:1000

It is BirdLife’s view that the authorities must work harder to present a balanced picture, and not allow automatic implication of wild birds as the likeliest vector every time an outbreak occurs. Even without additional evidence, the circumstances in these cases should have strongly suggested that other means of transmission were more likely:

1. Wild birds are not yet migrating, and (unlike early 2006) there have been no substantial movements of wintering birds in Europe in response to unusual weather conditions
2. There are active H5N1 surveillance schemes for wild birds in both Hungary and the UK. No suspicious deaths of wild birds have been reported. In the UK, 2,344 wild birds (found dead or shot by hunters) have been sampled since September 2006, with no H5N1 recorded.  Similar tests in Hungary (including also live birds captured for ringing) have also shown up no H5N1.
3. The two outbreaks have been in closed farms, at least one of which has high biosecurity. If H5N1 were present in the environment and being carried by wild birds, it would be much more likely that the virus would appear first in open, free-range poultry farms – but it hasn’t.

At present, swift action by the authorities appears to have contained these two outbreaks. The risk to public health from H5N1 remains very small. Detailed advice, answers to frequently asked questions and the updated BirdLife position statement can all be found by visiting the BirdLife Statement on Avian Influenza

AVIAN INFLUENZA, POULTRY VS MIGRATORY BIRDS (14)
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A ProMED-mail post
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ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>

Date: Tue 13 Mar 2007
From: Mary Mars****** <tropical.forestry@btinternet.com>
Source: EID, Volume 13, Number 4; April 2007 [edited]
<http://www.cdc.gov/eid/content/13/4/06-1072.htm>


"Movements of birds and avian influenza from Asia into Alaska." Kevin 
Winkler et. al.

Abstract:
Asian-origin avian influenza (AI) viruses are spread in part by 
migratory birds. In Alaska, diverse avian hosts from Asia and the 
Americas overlap in a region of intercontinental avifaunal mixing. 
This region is hypothesized to be a zone of Asia-to-America virus 
transfer because birds there can mingle in waters contaminated by 
wild-bird-origin AI viruses. Our 7 years of AI virus surveillance 
among waterfowl and shorebirds in this region (1998-2004; 8254 
samples) showed remarkably low infection rates (0.06 percent) [There 
were only 5 positive samples, and none were H5. - Mod.MHJ]. Our 
findings suggest an Arctic effect on viral ecology caused perhaps by 
low ecosystem productivity and low host densities relative to 
available water. Combined with a synthesis of avian diversity and 
abundance, intercontinental host movements, and genetic analyses, our 
results suggest that the risk and probably the frequency of 
intercontinental virus transfer in this region are relatively low.

Discussion:
Our surveillance did not show a "hotspot" of AI virus infection among 
avian hosts. Much higher infection rates are known from other 
multiyear surveillance studies at lower latitudes, e.g., Delaware Bay 
(4.7 percent, [32]), southern Minnesota (10.8 percent, [5]), and 
Alberta (22.2 percent, [32]) and British Columbia in Canada (55 
percent, although only a single-year study, [33]). The infection 
rates we found are substantially lower than those found for interior 
Alaska (9 percent, [12]). Arctic conditions in Alaska prevail well 
south of the Arctic Circle in the treeless regions of western Alaska, 
and the US Arctic includes the Alaska Peninsula and Aleutian 
Archipelago (34), a tundra ecosystem where our sampling was 
concentrated (for Figure go to source). Aerial surveys of waterfowl 
across Alaska show more ponds and fewer ducks per unit area on 
tundra; the number of ducks per pond on tundra habitat (2.1) is less 
than half the number found in the boreal-forest dominated interior 
(5.5, [18]). This simple ecologic factor (perhaps due to the lower 
productivity of these tundra ecosystems), resulting in the dilution 
of virus in waters with fewer available hosts, may in part explain 
our results. This is the 1st geographically and taxonomically 
extensive Arctic AI surveillance in North America, and it suggests 
that some Arctic effect lowers infection rates, thus lowering the 
risk of intercontinental viral transfer in these high-latitude 
regions. Our infection rates are low, comparable to those occurring 
at much lower latitudes (e.g., 9,35), whereas mid-latitude rates can 
be 2-3 orders of magnitude higher (33).

Human population densities in Alaska are relatively low, especially 
in the Beringian Crucible, and Alaska lacks a large agricultural 
sector. However, mammalian carnivores abound and could be susceptible 
hosts (36). Direct human infection from wild birds is possible, but 
transmission from birds to humans is difficult (37,38). Nevertheless, 
exposure in this region may be considerable; hunters kill around 99 
000 waterbirds for food each year on the Yukon-Kuskokwim Delta alone (39).

Although the existence of North American and Eurasian viral lineages 
is well established in the literature, evidence from other regions of 
North America has shown that geographic structure has been 
insufficient to prevent sporadic intercontinental exchange of some 
hemagglutinin subtypes (29,40). Our results can be considered to 
confirm the comparative rarity of such events in this important 
region of Alaska. Despite high diversity of host species and high 
numbers of individual birds in Alaska making intercontinental 
movements, the low AI infection rates and the genetic attributes of 
virus isolates (29) suggest that at most only small numbers of 
Asian-origin AI viruses or genes likely arrive in Alaska annually. 
Although AI viruses from Alaska have a clear link with other viruses 
in the lower 48 US states (29), the predominance of Arctic ecologic 
conditions and the lack of agriculture in the Alaska region most 
affected suggest a low risk for intercontinental viral transfer in this region.

References
5: Hanson BA, Stallknecht DE, Swayne DE, Lewis LA, Senne DE. Avian 
influenza viruses in Minnesota ducks during 1998-2000. Avian Dis. 
2003;47:867-71.
9: Chen H, Smith GJD, Li KS, Wang J, Fan XH, Rayner JM, et al. 
Establishment of multiple sublineages of H5N1 influenza virus in 
Asia: implications for pandemic control. Proc Natl Acad Sci U S A. 
2006;103:2845-50
12: Ito T, Okazaki K, Kawaoka Y, Takada A, Webster RG, Kida H. 
Perpetuation of influenza A viruses in Alaska waterfowl reservoirs. 
Arch Virol. 1995;140:1163-72.
18: Conant B, Groves DJ. Alaska-Yukon waterfowl breeding population 
survey [report]. Juneau (AK): US Fish and Wildlife Service; 2005.
29: Spackman E, Stallnecht DE, Slemons RD, Winker K, Suarez DL, Scott 
M, et al. Phylogenetic analyses of type A influenza genes in natural 
reservoir species in North America reveals genetic variation. Virus 
Res. 2005;114:89-100.
32: Krauss S, Walker D, Pryor SP, Niles L, Chenghong L, Hinshaw VS, 
et al. Influenza A viruses of migrating wild aquatic birds in North 
America. Vector-Borne Zoonotic Dis. 2004;4:177-89.
33: Canadian Cooperative Wildlife Health Centre. Avian influenza 
reports. 2006 [cited 12 Apr 2006]. Available from
<http://wildlife1.usask.ca/en/aiv/duck_survey_region.php>.
35: Stallknecht DE, Shane SM, Swank PJ, Senne DA, Kearney MT. Avian 
influenza viruses from migratory and resident ducks of coastal 
Louisiana. Avian Dis. 1990;34:398-405.
36: Thanawongnuwech R, Amonsin A, Tantilertcharoen R, 
Damrongwatanapokin S, Theamboonlers A, Payungporn S, et al. Probable 
tiger-to-tiger transmission of avian influenza H5N1. Emerg Infect 
Dis. 2005;11:699-701.
37: Beare AS, Webster RG. Replication of avian influenza viruses in 
humans. Arch Virol. 1991;119:37-42.
38: Shinya K, Ebina M, Yamada S, Ono M, Kasai N, Kawaoka Y. Avian 
flu: influenza virus receptors in the human airway. Nature. 2006;440:435-6.
39: Wentworth C. Subsistence harvest survey Yukon-Kuskokwim Delta, 
1995-2000 [report]. Anchorage (AK): US Fish and Wildlife Service; 2004.
40: Makarova NV, Kaverin NV, Krauss S, Senne D, Webster RG. 
Transmission of Eurasian avian H2 influenza virus to shorebirds in 
North America. J Gen Virol. 1999;80:3167-71.

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ProMED-mail
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[One should never say "never", but the authors' comment that "the 
risk and probably the frequency of intercontinental virus transfer in 
this region are relatively low" would seem to be cautiously on the 
high side, that is, the risk is probably negligible. - Mod.MHJ, JW]

[see also:
Avian influenza, poultry vs migratory birds (13) 20070216.0587
Avian influenza, poultry vs migratory birds (12) 20070214.0556
Avian influenza, poultry vs migratory birds (11) 20070213.0539
Avian influenza, poultry vs migratory birds (10) 20070131.0394
Avian influenza, poultry vs migratory birds (09) 20070124.0323
Avian influenza, poultry vs migratory birds (08): RFI 20070120.0262
Avian influenza, poultry vs. migratory birds (07) 20070111.0135
Avian influenza, poultry vs migratory birds (06) 20070108.0082
Avian influenza, poultry vs migratory birds (05) 20070107.0071
Avian influenza, poultry vs migratory birds (04) 20070105.0049
Avian influenza, poultry vs migratory birds (03) 20070103.0024
Avian influenza, poultry vs migratory birds (02) 20070103.0017
Avian influenza, poultry vs migratory birds 20070102.0013]
..........................................................mhj/msp/jw 

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