A computer simulation of the prevention of the transmission of Toxoplasma gondii on swine farms using a feline T. gondii vaccine

Nohra E Mateus-Pinilla, Bruce Hannon, Ronald M. Weigel

Research output: Contribution to journalArticle

Abstract

Transmission of Toxoplasma gondii on swine farms was investigated using a deterministic dynamic computer simulation model. A primary focus was to evaluate a feline T. gondii vaccine. Animal populations (swine and cats) were compartmentalized based on the stage of T. gondii infection. Simulations were run under conditions of closed and equilibrium population size. Model parameters were varied in a factorial experimental design to test the following hypotheses: T. gondii infection in finishing pigs decreases with (1) vaccination of susceptible cats, (2) an increase in the proportion of cats captured for vaccination, (3) a decrease in the initial number of cats, (4) a decrease in the initial T. gondii prevalence in cats and (5) a decrease in oocyst-survival time. Seeding conditions included a total of 10, 20, 30, 40 or 50 cats, initial T. gondii prevalences in cats of 30, 60 or 90%, vaccination of 0, 50 or 75% of the cats and two vaccination schedules (the field schedule from a prior trial and a weaning-vaccination schedule). Simulations were run at oocyst-survival times of 52, 39 and 26 weeks. T. gondii prevalence in finishing pigs was recorded every week for 10 years. The probability of elimination of T. gondii from finishing pigs increased with a decrease in the number of cats and a decrease in oocyst-survival time. The last-year average prevalence was used as the outcome in a multiple linear regression analysis. Decreased T. gondii prevalence in finishing pigs was the result of a decrease in the initial number of cats on the farm (squared semipartial correlation coefficient (sr2) = 47%), decreased oocyst survival (sr2 = 35%), using the weaning-vaccination schedule (sr2 = 7%) and vaccination versus non-vaccination (sr2 = 5%). Unexpectedly, the initial T. gondii prevalence in cats had no effect on T. gondii prevalence in finishing pigs. The simulation supports the field trial indicating vaccine effectiveness. However, vaccination had less impact on decreasing T. gondii infection in finishing pigs than a decrease in the number of farm cats.

Original languageEnglish (US)
Pages (from-to)17-36
Number of pages20
JournalPreventive Veterinary Medicine
Volume55
Issue number1
DOIs
StatePublished - Sep 10 2002

Fingerprint

Felidae
Toxoplasma
Toxoplasma gondii
computer simulation
Computer Simulation
Cats
Swine
Vaccines
cats
vaccines
farms
swine
Vaccination
vaccination
finishing
Oocysts
oocysts
Toxoplasmosis
Appointments and Schedules
Weaning

Keywords

  • Deterministic
  • Dynamic simulation
  • Finishing pigs
  • Modeling
  • Toxoplasma gondii
  • Vaccine-effectiveness

ASJC Scopus subject areas

  • Food Animals
  • Animal Science and Zoology

Cite this

A computer simulation of the prevention of the transmission of Toxoplasma gondii on swine farms using a feline T. gondii vaccine. / Mateus-Pinilla, Nohra E; Hannon, Bruce; Weigel, Ronald M.

In: Preventive Veterinary Medicine, Vol. 55, No. 1, 10.09.2002, p. 17-36.

Research output: Contribution to journalArticle

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