title: Comparison of viraemia- and clinical-based estimates of within- and between-pen transmission of classical swine fever virus from three transmission experiments.
abstract: Analyses of recent classical swine fever (CSF) epidemics in the European Union have shown that silent circulation of CSF virus (CSFV) occurs before the first outbreak is detected and this may lead to a large epidemic. However, severity of CSF disease signs may be linked with efficacy of disease transmission, the most severely affected animals having a higher infectivity than the less affected ones. The purpose of this study was to combine disease transmission quantification methods with CSF clinical signs quantification tools to investigate whether clinical signs, considered as infectivity markers, may allow us to calculate reliable estimates for disease transmission parameters. Data from three transmission experiments were used, varying according to the viral strain (Eystrup or Paderborn) and to the contact structure between experimentally inoculated and contact animals (direct or indirect contact). Within- and between-pen basic reproduction ratios (R0) were compared using viraemia data or clinical data. Between-pen R0 estimates were close and not significantly >1, with either strain or computation mode (using viraemia or clinical data). Conversely, within-pen R0s (Paderborn strain) computed using clinical data appeared higher than the estimates obtained using viraemia data. A models comparison (Bayes information criterion) showed a better fit of the clinical-based models, for both strains. This suggests that, in affected herds, the most severely affected animals could play a prominent role in CSFV transmission.
authors.affiliation: AFSSA-LERPAZ, Unité Epidémiologie, 22 rue Pierre Curie, BP 67, F-94703 Maisons-Alfort, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Durand
authors.forename: Sylvie
authors.initials: S
authors.lastname: Davila
authors.forename: Roland
authors.initials: R
authors.lastname: Cariolet
authors.forename: Alain
authors.initials: A
authors.lastname: Mesplède
authors.forename: Marie-Frédérique
authors.initials: MF
authors.lastname: Le Potier
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000821:virology; D000835:Animals, Wild / Q000821:virology; D006691:Classical Swine Fever / Q000453:epidemiology / Q000276:immunology / Q000401:mortality / Q000635:transmission*; D006692:Classical Swine Fever Virus / Q000235:genetics / Q000472:pathogenicity*; D005060:Europe / Q000453:epidemiology; D005062:European Union; D006799:Housing, Animal; D016019:Survival Analysis; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000401:mortality / Q000635:transmission*; D014765:Viral Vaccines / Q000627:therapeutic use; D014766:Viremia / Q000453:epidemiology / Q000276:immunology / Q000635:transmission / Q000662:veterinary*; D014774:Virulence
chemical_list: D014765:Viral Vaccines