Here is a link to a detailed and technical paper on PCR analysis that evaluates and outlines the problem with culturing CPn and the variations in abilities in different labs. It also talks about the results of split samples and concordance between some PCR approaches and discordance with others. Though this is highly technical, it answers the question of how can it be that there are still some researchers producing papers saying, for example, that they tested patients with MS for CPn and found the incidence to be no higher than controls, such as this article here but note that this one used antibody tests, a ridiculously ineffective way of looking for CPn in cryptic form in the brain. As the first paper in this editorial suggests, only PCR done well has any hope of elucidating this issue. The conclusion the second paper makes, that there is not evidence for CPn in MS lacks validity due to this methodological error.