The set up and analysis of transmission experiments with F4+ E. coli are described in this thesis and a definition of the infectious state based on the shedding patterns of individual animals was developed. No indication was found that reinfection affected the population dynamics of F4+ E. coli .
F4R+ piglets were found to be more susceptible to become infectious than F4R- piglets. It was concluded that the F4R status of the pig has a strong effect on the population dynamics of F4+ E. coli . The F4R status should therefore be used as a co-variate in the statistical analysis of F4 + E. coli intervention studies, both in challenge and transmission studies.The level of transmission is mainly dependent on the fraction of F4R+ piglets in the population.By reducing the fraction of F4R+ piglets in the population to <0.09 large outbreaks of F4+ E. coli will be prevented.
The heterogeneity in susceptibility may serve as a point of departure to control F4+ E. coli by selective breeding for F4R- pigs. With a simple discrete model, it was illustrated that selective breeding for F4R- piglets by using F4R- boars, is an effective way to reduce the fraction of F4R+ piglets in the population, given the presence of a sensitive F4R status test.
|Qualification||Doctor of Philosophy|
|Award date||13 Oct 2005|
|Place of Publication||Wageningen, The Netherlands|
|Publication status||Published - 2005|
- escherichia coli
- escherichia infections
- disease transmission
- population dynamics
- disease control
- selective breeding