THE INFLUENCE OF CONTACT STRUCTURE ON DISEASE TRANSMISSION IN A DAIRY HERD USING PARATUBERCULOSIS AS AN EXAMPLE

摘要

Pathogen transmission occurs by direct or indirect contact between susceptible and infected animals. The population structure is known to influence disease spread and persistence. The objective of this study was to evaluate how herd management influences contact structure and Mycobacterium avium subspecies paratuberculosis (Map) transmission within a dairy herd. A stochastic compartmental model of Map transmission in a closed herd was developed. Indirect transmission via the environment was explicitly modelled. Calves were housed in individual or group pens and different levels of exposure of calves to a contaminated environment were studied. It was found that, calf contact structure during the first weeks of life influenced Map prevalence. In addition, it was found that reducing the exposure of calves to adults had a larger impact on Map prevalence than hygiene measures and could lead to the fadeout of infection. The systematic analysis of contact structure used here can be applied to other diseases when developing realistic models to support decision making.