Classical Swine Fever

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VIRUSES
FLAVIVIRIDAE



Antigenicity

  • Isolates vary in virulence
  • Some antigenic variation
  • Best defined by monoclonal antibodies, but no serotypes

Hosts

  • Pigs
  • Wild boar

Pathogenesis

  • Virus enters oropharynx and replicates in palatine tonsil
  • Viremia 2-6 days post-infection

Two types of strain:

  1. Low Virulence:
    • Transplacental transmission causes abortion, cerebellar hypoplasia, or growth retardation
    • If piglets are born, they are carriers
  2. High Virulence:
    • Leukopenia
    • Thrombocytopenia
    • Generalized vasculitis
    • Hemorrhage of lymph nodes, spleen, bladder, larynx, and skin
    • Vasculitis in CNS causes tremors, incoordination and convulsions

Chronic disease:

Epidemiology

  • Recovered animals are immune
  • Highly contagious
  • Transfer via contact, aerosol, or fomites
  • Swine fever was once endemic worldwide but has now been eradicated from UK, Australia, NZ, USA, and Denmark following vaccination schemes

Diagnosis

  • Immunofluorescence of tissues for virus isolation
  • DD: Porcine circovirus 2, African swine fever, or bacterial septicemia

Control

  • NOTIFIABLE disease
  • Vaccination (live attenuated) in endemic countries:
    • Parts of EU are using vaccinated bait to control spread in wild boar population
    • Vaccination does not curtail spread: marker vaccine needed to distinguish virus exposure from vaccine-induced antibody