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[OUTBREAK:003297] ProMED概要 20040802-0010..20040803-0010
●06-01(0802-0040)#Ea#馬インフルエンザ、イヌ-米国（フロリダ州）# 情報源：DVM Magazine、6月1日。
フロリダ大学の研究者らが馬インフルエンザウイルスに対するイヌの感受性を示した。
フロリダ大学(UF)獣医学研究者らが初めて、馬インフルエンザが種の壁を超えてイヌにも感染することを示した。（以下、フロリダ州Jacksonvilleのイヌ飼育場で8頭のグレイハウンド犬が死亡した呼吸器疾患の原因が馬インフルエン ザウイルスである可能性を指摘する記載、後略。）
[Moderator注：馬インフルエンザウイルス1 型(H7N7)は1956年にヨーロッパで分離され、その後米国で分離された。2例目の馬インフルエンザウイルス(H3N8)
は1963年に米国で分離され、その後世界各地で分離されている。馬インフルエンザウイルス2型(H3N8)は最近の流行の大部分の病因であり、遺伝子配列検査 ではこのウイルス株が最初に分離されて以来わずかしか変異していないことが
示されている。これまでのところ、イヌでは特異的インフルエンザウイルスは確認されていない。1989年に中国東北部のウマで発生した、インフルエンザA ウイルスの深刻な流行は、広く流行している馬インフルエンザウイルスと同じ
抗原性を持ったウイルス株が原因であった。しかし、その際の病因ウイルスの別の遺伝子が鳥起源であったことから、遺伝子組み換え株の様であった。発病
したグレイハウンドから検出されたウイルスが、単に種の壁を越えて感染した馬インフルエンザウイルスであるのか、他の起源から遺伝子を獲得した組み換
え株であるのかを確認するのが重要であろう。こうした情報はこのイヌのウイルス株がヒトに感染伝播する可能性を評価するのにも重要となろう。]
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EQUINE INFLUENZA, CANINES - USA (FLORIDA)
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A ProMED-mail post
ProMED-mail, a program of the International Society for Infectious Diseases
Date: 1 Jun 2004
From: ProMED-mail
Source: DVM Magazine [edited]
UF researchers link equine influenza virus to canine susceptibility
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For the 1st time, University of Florida (UF) veterinary researchers believe
they have documented cases of equine influenza virus jumping the species
barrier into dogs.
The virus is the likely cause of a respiratory disease outbreak that killed
8 racing Greyhounds from kennels in Jacksonville. Although the outbreak
has been isolated and quashed, any time a virus jumps species it is considered
an important epidemiological event, the university reports.
Although researchers stress the findings involve only these particular
Jacksonville dogs, they will investigate possible connections to similar
disease outbreaks that have affected racing dogs in Florida and elsewhere
in recent years.
Cynda Crawford, DVM, Ph.D., a UF veterinary immunologist, explains, "I
want to stress that our team's findings are preliminary and confined to
the dogs affected by an outbreak at one Florida track, an outbreak that
occurred 3 months ago and was contained through a voluntary statewide quarantine,
which is no longer in effect."
UF's research team also worked with Cornell University's College of Veterinary
Medicine in Ithaca, N.Y., and the Centers for Disease Control and Prevention
(CDC). Ed Dubovi, director of virology section at Cornell's Animal Health
Diagnostic Lab isolated the virus. CDC was brought in to assess the public
health threat and monitor the outbreak.
"The virus found in the canine samples is probably representative
of the strain that is circulating now in horses in Florida and elsewhere
in the United States," says Ruben Donis, Ph.D. with CDC.
On the basis of genetic sequencing, Donis and colleagues at the Influenza
Branch conclude the virus found in canine samples resembled a strain of
equine influenza virus that appeared in horses in Wisconsin during 2003.
The researchers also found that the dogs developed antibodies specific
for the influenza virus.
"This implies that the virus replicated enough within the dogs for
their immune system to recognize it and form antibodies," Crawford
says.
Equine influenza is a disease of horses and is present in North America,
Europe and parts of Asia. Horses typically develop a fever and a dry, hacking
cough. In the early stages of the disease, horses are reluctant to eat
or drink for several days, but usually recover in 2-3 weeks.
Crawford adds that she is unsure how the Jacksonville Greyhounds could
have been exposed to equine influenza virus, and that is one of many questions
they intend to pursue through further epidemiological studies.
When Crawford learned about the January outbreak, she visited the Jacksonville
track to find 24 dogs affected with symptoms including cough, fever and
other more serious symptoms. Out of the total, 8 dogs died and 16 recovered.
Crawford reports she collected blood and nasal fluid samples from 35 dogs,
and 5 of the dogs that died underwent postmortem examinations.
The team also alerted dog owners not to experiment with prevention products
approved for other species because of the potential for adverse reactions,
including death.
[Details of the story provided by Sarah Carey, University of Florida.]
--
ProMED-mail
[Equine influenza virus 1 (H7N7) was isolated in Europe in 1956 and subsequently
in the USA. Then a second equine influenza virus (H3N8) was isolated in
1963 in the USA and subsequently elsewhere in the world. Equine influenza
virus 2 (H3N8) has been responsible for the majority of recent outbreaks
and sequencing studies indicate that equine influenza virus 2 virus has
undergone only slight genetic drift since first isolation. No influenza
virus has been designated as specific to canines so far. In 1989 a severe
outbreak of influenza A virus infection in horses in northeastern China
was caused by a virus withe the same antigenicity as the prevalent equine
influenza virus. However, it appeared to be a reassortant as its other
genes were of avian origin. It will be important to establish whether the
virus recovered from the affected greyhounds is an equine virus that has
simply jumped species, or whether it is a reassortant virus that has acquired
genes from another source. This information will be important in accessing
the potential of this canine virus for transmission to humans. - Mod.CP]
[see also:
Undiagnosed illness, canine - USA (FL)(02) 20040730.2081
Undiagnosed illness, canine - USA (FL) 20040701.1753]
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