WELLFLEET BAY VIRUS - USA: (MASSACHUSETTS) WILD DUCK
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Date: Sat 10 Mar 2012
Source: Cape Cod Times [edited]
<http://www.capecodonline.com/apps/pbcs.dll/article?AID=/20120310/NEWS/203100335>
A virus is not the kind of thing to have named after your town, but for the past 6 years scientists have focused on finding out why common eider ducks have been dying by the hundreds, sometimes thousands, in the fall along the shore of Wellfleet Bay [Massachusetts].
Veterinarians at Tufts Cummings School of Veterinary Medicine led the investigation, along with the University of Georgia-based Southeast Cooperative Wildlife Disease Study and the National Wildlife Health Center in Wisconsin.
"It's pretty clear, between what the National Wildlife lab found and from the Southeast Cooperative, that there is a new virus found in eiders in Wellfleet that hasn't been detected before," said Sarah Courchesne, project director for the Seabird Ecological Assessment Network at Tufts veterinary school.
Courchesne will be speaking about the research into the eider die-off at the Cape Cod Natural History Conference today [10 Mar 2012] at Cape Cod Community College.
Loosely related to the flu virus, it attacks the liver and gallbladder and seems to work very fast. Eider ducks collected from these mass die-offs appear healthy. They are not emaciated from a long illness [during] which they can't feed. "They basically die from liver disease," Courchesne said.
National Wildlife scientists discovered the virus while conducting necropsies on dead ducks but couldn't identify it. It was the scientists in Georgia who figured out the virus type and family, Courchesne said. They also named it: Wellfleet Bay virus.
So far, Wellfleet Bay is the only place in the world known to harbor this virus, although the scientists believe it is related to an equally mysterious Quarjavirus family that is distributed around the world. Ticks spread the diseases in colonies of nesting birds.
Researchers are now trying to discern whether ticks in Wellfleet are infecting the large flocks of eiders that congregate onshore and in the waters in the fall.
During large die-offs, workers collecting duck carcasses have noticed there were also sizeable rafts of eiders floating in the near shore waters. Eiders are not endangered or threatened; rather, they are a fairly common seabird with populations estimated to be in the hundreds of thousands. 50 000 or more have been spotted floating in huge groups in Nantucket Sound.
So far the disease appears to be confined to the portion of the eider population that summers in Maine and winters on the Cape.
Once they isolated the virus, researchers wanted to know whether they could replicate the disease and show it was the likely culprit. The National Wildlife lab infected eider ducklings with the virus, euthanized them and found the same lesions on the liver. "The eider, where we have a clear culprit, is one of those rare instances where we have found a thread this strong; it is rare for us and even more exciting," Courchesne said. Eiders face a different threat when they are in their summer breeding grounds with thousands dying from avian cholera.
Courchesne is concerned about the possibility of a major population decline because of consecutive years in which these twin diseases take large chunks out of the population of adult breeding-age birds.
Global warming and loss of habitat also make birds more vulnerable to disease, Courchesne said. Habitat loss means birds crowd together in the remaining wild areas, making transmission of disease that much easier. As temperatures rise, ticks can expand their range and remain active longer each year. Plus less temperature-tolerant diseases can also spread north infecting species which don't have a natural defense against them. "Climate change could have a huge impact," she said.
[Byline: Doug Fraser]
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ProMED-mail from HealthMap alerts
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[These common eider (_Somateria mollissima_) mortality events at Cape Cod Bay have been puzzling scientists since 2006. A multi-agency investigation has finally pinpointed the etiology. The novel Wellfleet Bay virus is an Orthomyxovirus, an RNA virus like the influenzas, although this particular type is related to those that are transmitted by arthropod vectors. The pathogenicity of the virus was demonstrated experimentally in eider ducklings.
Portions of this comment were extracted from <http://www.aphis.usda.gov/wildlife_damage/nwdp/pdf/The%20Carrier%20Vol%204%20Iss%201.pdf>.
A picture of a common eider duck can be seen at <http://upload.wikimedia.org/wikipedia/commons/6/6f/Somateria_mollissima_male..jpg>.
The state of Massachusetts can be located on the HealthMap/ProMED-mail interactive map at <http://healthmap.org/r/1_I2>. - Mod.PMB]
[see also:
Undiagnosed die-off, avian - USA: (MA) swans, RFI 20120106.1001760
2004
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Waterfowl die-off - USA (ND) 20040729.2070] .................................................sb/pmb/mj/jw/ll
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