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A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Tue 2 Feb 2010
Source: The Missoulian [edited]
Deadly pneumonia infections have appeared in a 4th herd of bighorn
sheep this winter.
The latest outbreak was spotted over the weekend in Upper Rock Creek,
in a herd about 12 miles south of the also-infected Lower Rock Creek
herd.
Montana Fish, Wildlife and Parks biologist Ray Vinkey said he killed 3
Upper Rock Creek bighorns on Saturday [30 Jan 2010] and all had the
highly infectious disease. That's in addition to the 6 infected sheep
he took last week in the lower part of the drainage.
The 2 herds are separated by deep canyons and thick timber. Although
there hasn't been much genetic study or radio-collar work, biologists
have found little evidence that the 2 herds mingle. That leaves the
cause of the pneumonia spread a mystery.
"We still don't have a bigger picture," FWP Region 2 wildlife manager
Mike Thompson said on Monday [1 Feb 2010]. There are theories about
rams wandering from herd to herd or some stress-related factor
triggering the outbreaks, but no hard evidence has surfaced yet.
The Rock Creek sheep are at least 20 air miles from bighorn herds in
Bonner and Darby, where pneumonia has run through the respective
populations. FWP hunters culled 88 sheep from the Bonner herd above
West Riverside as of Monday [1 Feb 2010], and took 77 sheep from the
East Fork of the Bitterroot south of Darby last November [2009].
The goal was to kill infected sheep before they could pass the disease
to healthy bands. Bighorn pneumonia kills 70 percent to 90 percent of
its victims within a few weeks, and there is no effective vaccine or
treatment for it in the wild. Preliminary surveys of the East Fork
herd found 71 healthy sheep in the area after the cull there.
Vinkey said a similar cull may take place in the Upper Rock Creek
herd. Those sheep live in relatively accessible terrain. He planned to
make an aerial survey of the area later this week to determine how
widespread the outbreak is within the roughly 360-animal herd.
FWP will kill at least 10 to 20 diseased sheep in Upper Rock Creek for
analysis to identify the disease organism, and investigate whether the
4 pneumonia outbreaks might be related, he said.
A report from an interested citizen who volunteered to watch the sheep
for FWP last week, resulted in the 1st detection. A local rancher
helped Vinkey kill 2 ewes and a young ram on Saturday [30 Jan 2010],
and perform the necropsies that confirmed pneumonia is present.
"Reports from the public were responsible for the 1st detections of
pneumonia in all 4 recent outbreaks," said Vivaca Crowser, regional
information manager. "These reports from the public give us the chance
of detecting the disease in its early stages, and we need the public's
help to alert us to any possible outbreaks in other herds."
The Upper Rock Creek bighorn herd is a native population that was
supplemented by the addition of 31 sheep (21 ewes, 10 rams) from Sun
River in 1975. That herd was over its population objective and plans
were under way to capture up to 40 of its members for transplanting to
Utah in the next 2 months. The disease outbreak scrapped those plans,
Vinkey said.
The 200-animal herd in Lower Rock Creek lives in much steeper and
rocky hillsides, and probably can't be culled successfully.
Pneumonia does not appear to have reached large herds in the Anaconda
area 20 miles [32 km] east of Rock Creek or the Skalkaho Pass area 18
miles [29 km] to the southwest. Both of those areas have tough terrain
dividing the sheep habitats.
[Byline: Rob Chaney]
--
Communicated by:
ProMED-mail
[It has been suggested that an autogenous vaccine could be made.
Likely the vaccine would have to be made for oral consumption as
rounding these animals up might be quite difficult on man and animal.
However, it seems the tool of technology may not be applied as much as
the reliance on culling because it has always been done that way.
ProMED-mail would be grateful if someone involved in the situation
could give us an update of the technology that has been considered and
why it has been rejected.
For more information on the pneumonia affecting the bighorn sheep,
readers are encouraged to read the moderator's comments on ProMED-mail
post 20091126.4055.
Photos of bighorn sheep may be found at
The state of Montana in the Western United States can be seen on the
HealthMap/ProMED-mail interactive map at
[Would any knowledgeable reader care to speculate on how a supposedly
ovine-specific peneumonia could spread up to 20 miles between herds
separated by supposedly impassable terrain? My bet is it would have
tp be by birds -- but what avian species interact with bighorns?
Tick-birds? - Mod.JW]
[see also:
Pneumonia, ovine - USA (04): (MT), bighorn sheep 20100124.0272
Pneumonia, ovine - USA (03): (MT), bighorn sheep 20100124.0262
Pneumonia, ovine - USA (02): (MT), bighorn sheep 20100117.0197
Pneumonia, ovine - USA: (NV) bighorn sheep 20100109.0105
2009
----
Pneumonia, bighorn sheep - USA (02): (MT) 20091203.4129
Pneumonia, bighorn sheep - USA: (MT) 20091126.4055]
........................................sb/tg/mj/jw
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