Figure 3. A model for how heterogeneity is transmitted through the infectious dose.

Colors represent different mutation profiles in a subclone (i.e., a subclonal mutation present in a fraction of the population). Heterogeneity in the preceding animal in the infectious chain may lead to different mutations being transmitted in different animals even though they were infected from the same carcass. The vertical black boxes represent the soil/sediment and can be seen as a randomizer mixing the spores which will infect next host. A clonal mutation (i.e., one present in the whole population) is valuable for tracing purposes but may be subclonal in the preceding case. Thus, it is evident that there is a need to analyze several isolates to determine the clonality of the observed mutations and to fully comprehend the transmission chain.