NDOANDOWUNR Pasteurella Project and Bighorn Sheep Study

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NDOA-NDOW-UNR Pasteurella Project and Bighorn
Sheep Study

• NAES funded Research Project
• Gabriela Aviles, PhD and Craig Beattie, PhD - UNR
• Anette Rink, DVM, PhD and David Thain, DVM NDOA
• Mike Cox, MS and Terry Craforth - NDOW

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Experimental Design

• Sampling of 30 ewes and 30 lambs in 6 domestic
  flocks three times in a three year period
• One summer, one winter and one spring or fall
  sampling
• Sampling of all Bighorn sheep marked by NDOW for
  capture and relocation (since 2002)
• Hunter kill sampling (2002 to 2004)

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Sampling protocol

• Domestic sheep and live Bighorn sheep
• Nasal and pharyngeal swabs
• Bacterial culture and isolation of Mannheimia
  (P.) hemolytica, P. multocida and P. trehalosi
• Fecal sampling (lungworms, gastrointestinal
  parasites)
• Blood sample
• Serology (Ovine Respiratory panel)
• Mineral (Se) deficiencies

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Sampling protocol (cont)

• Hunter kill samples
• Blood sample
• Nasal/pharyngeal swab
• Fecal sample
• Lung tissue
• Lung lesions are the target
• Detection of bacterial DNA and source of sheep
  genomic DNA for population genetic studies.

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Current Status

• 660 domestic sheep have been sampled
• (330 ewes and 330 lambs)
• - M. hemolytica prevalence varies between 20 to
  50 in ewes and 10 to 70 in lambs. Parasite
  prevalence ranged from lt5 to 98 (mostly
  Coccidia) in different flocks.  
• gt 250 Bighorn sheep have been sampled
• M. hemolytica prevalence varies between 25 and
  60 depending on location and season.
• Low prevalence of Coccidia (lt 10) and
  Trichostrongyles (10)
• Higher prevalence of small lung worms (ca. 40)
• Rare detection of tape worm

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Current Status (cont.) and proposed time lines

• Preliminary genetic characterization of M.
  hemolytica isolates from healthy Bighorn sheep
  gt70 contain leukotoxin genes
• Bacterial genotyping started in January 2005,
  completion Januray 2006 (all strains)
• Flock sampling completed by December 2005
• Bighorn Sheep DNA genotyping data available
• January 2005 (preliminary results February
  2005)

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Amplified Fragment Length Polymorphism (AFLP)
Image showing two M. hemolytica isolates and 8
Primer Combinations
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1. What do we know about the Pneumomia complex
based on the literature and recent field studies?

• It is multifactorial!
• Macro (kJ, Prot) and micro nutrient (Se)
  deficiency probably most prevalent
• Inclement weather, wild fire, soil pH etc.
• Enzootic verminous pneumonia (life cycle)
• Pneumotropic (BRSV, PI-3, IBR) and other enzootic
  viruses (BVD, BT, EHD)
• Bacterial diseases (Pasteurella complex,
  Corynebacterium)
• Long list of publications which represent the
  bigger picture
• In the 90s a series of publications
  transitioned to tunnel vision approach (single
  cause studies) all revolving around Pasteurella
  spp., many of which completely ignore enzootic
  pneumonia in BHS and Kochs postulates!!!!!
• 1. The specific organism should be shown to be
  present in all cases of animals suffering from a
  specific disease but should not be found in
  healthy animals.
• 2. The specific microorganism should be
  isolated from the diseased animal and grown in
  pure culture on artificial laboratory media.
• 3. This freshly isolated microorganism, when
  inoculated into a healthy laboratory animal,
  should cause the same disease seen in the
  original animal.
• 4. The microorganism should be re-isolated in
  pure culture from the experimental infection.

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January-July 2004 Bighorn Sheep Die-off in the
Santa Rosa Mountains

• Domestic sheep were observed on Sawtooth
  mountain, Orovada mid December 2003
• One domestic wether was killed and sampled
• - No parasites were present, no Pasteurella
  species were isolated
• January 8th, 2004 two Bighorn sheep were
  sacrificed for diagnostic purposes
• Most significant findings
• Chronic verminous and acute bacterial (M.
  hemolytica) pneumonia
• Selenium deficiency
• Old lung lesions indicative of BRSV infection
  (titer 120/140)

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What is your interpretation of the literature and
recent field studies?

• Significantly different Philosophies lead to
  significantly different approaches to investigate
  the Pneumonia complex
• 1. School of Domestic sheep/livestock are the
  problem
• Response Get the sheep off the range.
• 2. School of Lets find out what happened.
• The potential for disease transmission from
  livestock is recognized and investigated if
  indicated.
• Existence of endemic Pasteurella
  Pneumonia/Pneumonia complex in BHS populations is
  recognized
• A comprehensive diagnostic work up is initiated.
• Interpretation of diagnostic results in a
  context!
• Recognition of vulnerability of completely
  susceptible populations.
• Response Exploration of vaccination strategies,
  creation of stable endemic situation.
• Attempt to develop a viable management plan.

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What is the risk of disease transmission to the
Sierra Nevada BHS, within the potential of other
stressors?

• Unknown!....and Zero Risk is unobtainable!
• According to recovery plan historically lt 30.
• Risk increases with
• Loss of Immunity The longer the isolation, the
  higher the risk of complete morbidity and
  mortality due to complete population
  susceptibility (migrating BHS rams/domestic
  livestock/cohabitating wildlife species).
• Suboptimal Nutrition/unacceptable habitat Forage
  quality and availability, avoidance of winter
  range due to predation (increase of groundcover
  due to cessation of grazing?).
• Loss of heterozygosity due to inbreeding.
• If every domestic sheep were to be taken off the
  range today Bighorn sheep would still die from
  Pneumonia complex associated diseases.
• The real question is would there be more or less
  disease and death?