Epidemiology of Eimeria acervulina infections in broilers : an integrated approach

Understanding of factors that influence the epidemiology of Eimeria acervulina infections was increased by combined theoretical, experimental and field work. First, a simulation model was developed. Second, principles and phenomena as observed in simulation results were validated by conducting experiments in broilers. The research described in this thesis was focused on (qualitative) validation of the simulation model. The model was, in contrast to expectation, relatively insensitive to the sporulation rate of oocysts. Host immunity and anticoccidial drug efficacy, however, influenced model outcomes substantially. These aspects were tested experimentally. Simulation results showed existence of an optimal initial contamination level. This hypothesis was also tested in an experiment. From a qualitative perspective the simulation model behaves realistically. Quantitative agreement between simulation and experimental results was less satisfactory, which illustrates the need for better calibration of parameters and change of relationships in the current model. Finally, environmental and management factors that are associated with coccidiosis were studied using field data.