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A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Tue 22 Jun 2010
Source: The Guardian [edited]
A mystery disease is driving the Siberian tiger to the edge of
extinction and has led to the last animal tagged by conservationists
being shot dead in the far east of Russia because of the danger it
posed to people.
The 10-year-old tigress, known to researchers as Galya, is the 4th
animal that has had a radio collar attached to it for tracking to die
in the past 10 months. All had been in contact with a male tiger
suspected of carrying an unidentified disease that impaired the
ability to hunt. "We may be witnessing an epidemic in the Amur tiger
population," said Dr Dale Miquelle, the Wildlife Conservation
Society's (WCS) Russia director.
Galya had recently abandoned a 3-week-old litter of cubs and come
into the town of Terney looking for an easy meal. Following a series
of all-night vigils by researchers, attempts to scare the tigress
away failed. She was reported to the Primorsky State Wildlife
Department as an official "conflict tiger," and a state wildlife
inspector was called in to destroy her earlier this month [June 2010].
"This tiger had lost its fear of humans; typically, Amur tigers will
never expose themselves for observation. It was like seeing someone
you know turn into a vampire," Miquelle said.
Scientists are attempting to understand what compromised the
tigress's ability to capture wild prey, which she had lived upon
almost exclusively since birth. Her cubs, which were subsequently
found dead at the den, are likely to have had their mother's disease
transmitted to them through the placenta. "Initial necropsy results
show an empty digestive tract, which is highly unusual. We're still
waiting for results of further tests, but the abnormal behaviour
suggests disease, possibly neurological," said Miquelle. "We are
extremely concerned about the possibility of an epidemic that could
be sweeping through this region. Animals we have studied extensively,
and known well, have demonstrated radically changed behaviour, which
is extremely disconcerting."
Weighing only 91 kg at death -- down from an estimated 140 kg at full
health -- the tigress's death represents the end of an 11-year
lineage of related "study" tigers and leaves the WCS's Siberian Tiger
Project with no radio-collared animals for the 1st time in 18 years.
WCS Russia has tracked more than 60 tigers since inception in 1992.
In March this year [2010], Miquelle raised the prospect of disease as
a potential threat to an already endangered Siberian tiger
population. WCS Russia reported in October 2009 that there had been a
40 percent decline in numbers since the last full survey in 2005,
from 428 to as little as 252 adult tigers. The tiger's range has been
reduced to a small pocket in the corner of the country within the
region of Primorsky Krai.
Speaking at a conference in Vladivostok, Miquelle said that anything
above a 15 percent mortality rate in adult females could kill off all
Amur tigers. With around 150 adult females in the population, any
more than 22 deaths of adult females per year may wipe out the
species. Poaching accounts for about 75 percent of all Amur tiger
deaths, with 12 to 16 adult females killed annually. "We're in a new
era where disease could seriously affect the Amur tiger."
The Russian draft federal tiger conservation strategy has recently
been amended to take account of disease, including a section on
vaccination against canine distemper, a viral disease which is common
in the Russian far east in domestic dogs and cats.
"The addition of disease-related deaths to existing sources of
mortality could push this population over a tipping point," said Miquelle.
The federal strategy, which is being designed by a number of
scientific groups including WCS Russia, is being prepared for the 1st
global Tiger Summit due to take place in St Petersburg this September
2010. Along with World Bank president Robert Zoellick, Vladimir Putin
is due to preside over the conference.
WCS Russia hopes to recommence the capture of study tigers in
September 2010. "We aim to change the focus of why we study tigers,
with a new emphasis on disease," said Miquelle. "The only consolation
in this grisly process is that, for once, a serious threat is not
originating from human actions, although even that, for now, is open
to debate."
--
Communicated by:
ProMED-mail
[The speculation of an infectious disease being behind the described
cases is in need of laboratory investigative efforts, including CNS
histology. Before doing so, rabies should be excluded, although
regarded as a remote possibility. Some of the candidate etiologies
are avian influenza, babesiosis, _Bartonella henselae_ infection,
Borna disease, cryptococcosis, feline infectious peritonitis (FIP --
dry form), FSE (feline spongiform encephalopathy) and toxoplasmosis.
Environmental and toxic factors are to be taken into consideration as well.
Results of the expected investigations are requested. For a picture
of the Amur tiger (_Panthera tigris altaica_) see
[see also:
Feline infectious peritonitis - USA: (MI) 20100506.1470
2007
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Feline spongiform encephalopathy, cheetah - Germany 20070913.3038
2006
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Avian influenza (140) - Indonesia (cat) 20060620.1700
2005
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Rabies, feline - USA (IL) 20050515.1338
2004
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Avian influenza - Eastern Asia (127): Thailand, tigers 20041019.2838
2002
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Feline spongiform encephalopathy, zoo - Australia 20020731.4902
2001
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Feline spongiform encephalopathy, cat - Switzerland 20010717.1384
1998
----
Feline spongiform encephalopathy: current status 19980302.0406
1996
----
Feline spongiform encephalopathy 19960610.1077]
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