Modelling the time-dependent transmission rate for porcine circovirus type 2 (PCV2) in pigs using data from serial transmission experiments

J R Soc Interface. 2009 Jan 6;6(30):39-50. doi: 10.1098/rsif.2008.0210.

Abstract

Six successive transmission trials were carried out from 4 to 39 days post inoculation (DPI) to determine the features of the infectious period for PCV2-infected pigs. The infectiousness of inoculated pigs, assessed from the frequency of occurrence of infected pigs in susceptible groups in each contact trial, increased from 4 to 18 DPI (0, 7 and 8 infected pigs at 4, 11 and 18 DPI, respectively) and then decreased slowly until 39 days post infection (4, 2 and 1 pigs infected at 25, 32 and 39 DPI, respectively). The estimated time-dependent infectiousness was fitted to three unimodal function shapes (gamma, Weibull and lognormal) for comparison. The absence of infected pigs at 4 DPI revealed a latency period between 4 and 10 DPI. A sensitivity analysis was performed to test whether the parametric shape of the transmission function influenced the estimations. The estimated time-dependent transmission rate was implemented in a deterministic SEIR model and validated by comparing the model prediction with external data. The lognormal-like function shape evidenced the best quality of fit, leading to a latency period of 8 days, an estimated basic reproduction ratio of 5.9 [1.8,10.1] and a mean disease generation time of 18.4 days [18.2, 18.5].

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Circoviridae Infections / transmission
  • Circoviridae Infections / veterinary*
  • Circovirus / genetics*
  • DNA Primers / genetics
  • Enzyme-Linked Immunosorbent Assay
  • Likelihood Functions
  • Models, Biological*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sensitivity and Specificity
  • Sus scrofa
  • Swine Diseases / transmission*
  • Time Factors

Substances

  • DNA Primers