Pathogens in Milk: Mycobacterium spp.

Members of the Mycobacterium genus are ubiquitous in the environment. Although the majority are harmless, some, such as the members of the Mycobacterium tuberculosis complex, can cause severe pulmonary disease as well as intestinal and disseminated disease in humans. Nontuberculous mycobacteria are also becoming of increasing medical relevance especially among individuals with a defective immune system. These mycobacteria have an extremely wide host range and are seen to colonize and infect many important domestic animals, wildlife, and humans. Many of the mycobacteria that are capable of causing disease in humans can be found in raw milk. Even though this mode of transmission is of less relevance in the developed world, it is becoming increasingly important in the developing world. This is because of the effective pasteurization and mycobacterial control measures implemented in developed countries are either absent or only partially implemented in developing countries. Ineffective control of these pathogens in dairy herds, coupled with a population possessing a defective immune system, either through malnourishment or due to HIV infection, has led to increasing mycobacterial infections in the developing world.