Slow infection control by vaccination: paratuberculosis.

Classical causality models for infectious diseases have fulfilled an important role in the progress of medical sciences, however, new forms of association where weakly pathogenic agents cause widespread infections that mostly do not progress to disease, but that if they do so, cause protracted clinical courses where the host resources are exhausted fit better with the slow infection concept proposed over half a century ago. This model could show an infectious cause behind some diseases that have never fulfilled the conventional criteria. While new mechanisms of causation are defined, these diseases still need to be controlled to allow sustainable animal production. Here, I discuss the case of paratuberculosis control by vaccination as an example of the benefits of using a theoretically preventive treatment to modify the course of infection towards preventing clinical disease even though the infection itself might not be fully controlled.