Persistence of Mycobacterium bovis under environmental conditions: is it a real biological risk for cattle?

Mycobacterium bovis has a wide range of hosts. Usually, it affects cattle; however, it has been detected in humans and many wildlife reservoirs such as cervids, badgers, feral pigs, brushtail possums, and buffaloes. Persistence in wildlife has made it difficult to eradicate M. bovis, even in developed countries. The main route of M. bovis transmission is by aerosol through the respiratory tract; direct contact between cattle and wildlife is the explanation for transmission between species. However, depopulated farms have experienced recontamination after cleaning and disinfecting and months of not having cattle, suggesting persistence of M. bovis in contaminated plants, soil, and water. The question remains as to whether M. bovis persists in the environment for long periods of time and is capable of causing new outbreaks. We show that M. bovis in the environment is a risk for cattle if some key environmental conditions are present: appropriate substrate, temperature, desiccation, and sunlight. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.