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Á¦¸ñ ¹Ù´ÙÇ¥¹ü Influenza·Î »ç¸Á °ü·Ã ÀÚ·á
ÀÛ¼ºÀÚ arseidon
ÀÛ¼ºÀÏÀÚ 2016-04-28
Á¶È¸¼ö 1142
¹Ù´ÙÇ¥¹ü Influenza·Î »ç¸Á °ü·Ã ÀÚ·á  
DIE-OFF, SEAL - USA (03): NEW ENGLAND, INFLUENZA
************************************************
A ProMED-mail post
<
http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<
http://www.isid.org>

Date: Tue 20 Dec 2011
Source: The Boston Globe [edited]
<
http://bostonglobe.com/metro/2011/12/20/flu-virus-linked-seal-deaths-off-new-england-coast/CGm1ytfcDbuxc0msgNnT9J/story.html>


A flu virus similar to one found in birds but not previously detected
in harbor seals was the cause of 5 of 162 recent deaths of the marine
animals off the New England coast, federal and state officials said
yesterday [19 Dec 2011].

The influenza virus, known as H3N8, appears to have a low risk for
transmission to humans, they said. But officials are urging the public
to be cautious about approaching stranded seals to reduce the
potential risk of spreading the infection to people or their unleashed
dogs.

"Influenza that poses a risk to people are human strains of influenza,
but there have been documented cases in people of transmission from
other species," said Dr. Catherine M. Brown, public health
veterinarian for the Massachusetts Department of Public Health.

Other viruses that caused global disease outbreaks in years past, such
as avian and swine flu, jumped from birds and pigs to humans, usually
through the animals' caretakers, Brown said. She said there have been
an increasing number of instances in the past decade of flu viruses
jumping from one species to another.

As Dr. Teri Rowles, a marine mammal coordinator at the National
Oceanic and Atmospheric Administration's fisheries service put it: "We
all understand the connectivity between wildlife health and human
health and ocean health."

Federal scientists have been working with researchers from the New
England Aquarium and various centers around the country to investigate
the string of seal deaths since September 2011 along coastline
stretching from Massachusetts to Maine.

Young harbor seals accounted for most of the deaths, which were coming
at a pace roughly 3-4 times the normal number in September and October
2011, said Dr. Charles Innis, the aquarium's chief veterinarian. The
death rate has slowed since late November 2011.

The specialists said in a press conference that they believe the
influenza type A virus that infected the seals left them vulnerable to
a bacterial pneumonia that killed 5 of them, all off New Hampshire's
coast. They said that land-based animals such as wild birds that were
infected suffered upper respiratory infections, and most recovered.

"We don't understand at the moment what is making this virus more
deadly," said Dr. Hon Ip, a researcher at the US Geological Survey
Wildlife Health Center. Ip said earlier deaths of seals have been
traced to an influenza virus but that they were few and far between
since the 1970s.

The scientists said they will continue to study the strandings and
test tissue samples taken from some of the dead seals to determine how
many others may have been infected by the virus.

So far, only harbor seals appear to have been affected, but the
scientists said they will be investigating whether the virus has
infected gray seals and harp seals, and they will be working with
scientists in Canada to monitor the health of harbor seals in Canadian
waters.

Some studies have indicated that certain contaminants can adversely
affect marine mammals, such as polychlorinated biphenyls, or PCBs, a
lubricant banned in the United States in the 1970s because of evidence
it harmed fish and other wildlife. The substance is slow to break down
and persists in the environment.

Rowles, the NOAA fisheries coordinator, said researchers have not seen
any signs of a spike in PCB levels in the dead seals they have studied
so far.

"That is something that, as we move forward, we will look for and
test?" Rowles said, "but at this point, we have no evidence that
there is something abnormal for PCB loads or other contaminants."

[Byline: Kay Lazar]

--
Communicated by:
ProMED-mail <promed@promedmail.org>

[Influenza A viruses are classified according to subtypes that are a
combination of 16 possible HAs (hamaglutinin) and 9 possible NAs
(neuraminidase). All H3N8 viruses belong to the same subtype, but this
does not necessarily mean they are the same virus. The fact that only
5 out of 162 stranded tested seals were positive suggests that this
virus might not be the major health problem these seals are facing.
Apparently, there is no evidence either that the virus is now
"deadlier." In the past (1979-1983), influenza A virus was isolated
from seals which had died from pneumonia in New England. It is
relevant to establish whether other stranded animals also had
pneumonia.

The interactive HealthMap/ProMED-mail map for New England is available
at: <
http://healthmap.org/r/1xMA>. - Mod.PMB]

[This appears to be the first time that A/(H3N8) influenza virus
viruses have been associated with mortality in marine mammals.
Influenza A(H3N8) virus is commonly associated with ducks and other
wild aquatic birds. This may conceivably be a route of exposure of
marine mammals such as seals to this virus, but it would be premature
to assume this. Two other distinct groups of A/(H3N8) influenza
viruses infect horses and dogs. Recent analyses of these viruses
suggest that the canine and equine viruses are separately evolving
groups. Rivailler et al. (Virology. 2010 Dec 5;408(1):71-9) have
investigated the canine and equine influenza (H3N8) viruses
co-circulating in the the USA during the period between 2005 and 2008.
The genomes of the influenza A /(H3N8) viruses isolated from numerous
dogs and horses were sequenced to determine their origin and
evolution. Phylogenetic analyses revealed that the A/(H3N8) influenza
viruses isolated from horses and dogs were monophyletic and distinct.
There was no evidence of canine influenza virus infection in horses
with respiratory disease or new introductions of equine influenza
viruses into dogs in the United States. Analysis of a limited number
of equine influenza viruses suggested substantial separation in the
transmission of viruses causing clinically apparent influenza in dogs
and horses. It may be that a distinct group of influenza A/(H3N8)
viruses is already present in seal populations. Genomic analysis will
help to resolve this issue. - Mod.CP]

[see also:
Die-off, harbor seals - USA (02): New England, influenza
20111215.3607
Die-off, harbor seals - USA: northeast, influenza susp. 20111106.3301
Die-off, seal - USA: New England, RFI 20111027.3203
Die-off, marine wildlife - USA (02): (AK) seal, RFI 20111014.3074
Die-off, marine wildlife - USA: (NH) RFI 20111012.3052
Q fever - USA (02): (AK) seals 20110911.2771
2007
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Die-off, marine wildlife - USA (03): (AK) seal, walrus 20070518.1580
Die-off, seals - Kazakhstan (Mangistauskaya): RFI 20070418.1280
2003
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Phocine distemper virus, seals - UK 20030112.0099]
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