Porcine Circovirus PCV2 Infections

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Porcine Circovirus (PCV-2) Infections
Dr. Russ Daly DVM Extension Veterinarian South
Dakota State University, USA russell.daly_at_sdstate.
edu

• Last update 11/28/06

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Porcine Circovirus

• The current emerging swine disease issue in
  North America
• Clinical forms
• Postweaning Multisystemic Wasting Syndrome (PMWS)
  in nursery pigs
• Infectious Congentital tremors in baby pigs
• PCV-Associated disease emerging issue in
  finishing pigs

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Porcine Circovirus

• 1982 First discovered as a contaminant of cell
  culture
• 1982-94 Serology identifies widespread exposure
  to PCV throughout the world
• 1994 PCV linked to infectious congenital
  tremors in baby pigs
• 1997 PCV linked to Postweaning Multisystemic
  Wasting Syndrome
• 2005 PCV associated with more severe disease in
  older pigs (Canada)

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Circovirus Agent Factors

• Virus first identified in 1982
• Family Circoviridae
• Non-enveloped, DNA virus
• Two types Types 1 and 2
• Type 1 currently not associated with disease

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Circovirus Agent Factors

• Some strain differences are apparent
• Differences in ability to infect pigs
• Normally shed in nasal secretions, feces
• Seem to be hardy in the environment
• Disinfection Aldehydes, bleach, iodides

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Circovirus Host Factors

• Species Limited to swine
• Some serologic evidence that other species
  (cattle, humans) can become infected
• Age
• Congentital tremors limited to suckling pigs
• PMWS limited to nursery pigs
• Emerging PCV-Associated Disease 13-18 week old
  pigs (finisher stage)

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Circovirus Host Factors

• Concurrent Infection with other agents
• PRRS, Influenza, M. Hyo, Strep. suis, H. parasuis
• Disease expressed more easily
• Stress
• Vaccination status??
• Some feel vaccination may trigger symptoms
• Oil-in-water adjuvants implicated with more
  severe lesions in PCV-infected pigs

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Environmental Factors

• Management
• All-in All-out or Continuous Production?
• Co-mingling and mixing
• Pig density

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Syndromes Circovirus

• PMWS Post-weaning Multisystemic Wasting Syndrome
• Pigs 6-8 weeks of age
• Rare in suckling pigs
• Symptoms
• Low morbidity, but high case-fatality rate

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Syndromes Circovirus

• PMWS Post-weaning Multisystemic Wasting Syndrome
• Pathogenesis
• PCV replicates in lymphoid tissues (lymph nodes,
  spleen, thymus), nasal mucosa, lung, small
  intestine
• Difficult to reproduce experimentally
• Lesions

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Syndromes Circovirus

• Infectious Congenital Tremors
• Bilateral tremors of skeletal muscles
• Range from mild to severe
• May subside when pig laying down or sleeping
• Severe tremors may ? inability to nurse ?
  starvation
• If pigs make it past one week of age will likely
  survive

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Syndromes Circovirus

• Emerging PCV-associated disease
• Affects older pigs 13-18 weeks 4-8 weeks after
  entering finisher
• Cases are complicated with PRRS, Influenza, M.
  hyo, others
• Symptoms

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Syndromes Circovirus

• Emerging PCV-associated disease
• 30-50 morbidity 7-30 mortality
• More severe disease associated with
• Off-site production
• Multi-source groups
• PRRS-() systems

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Control of Circovirus?

• No specific treatment available
• New vaccines
• Suvaxyn PCV2 One Dose (Ft. Dodge)
• Ingelvac Circoflex (BI)
• Minimize stress
• Environment, mixing, moving, pig density
• Eliminate or diminish co-infections (PRRS, etc.)
• Oral, injectible anti-inflammatories
• Evaluate vaccine practices