Microbes without borders, an agenda for the ^21st century

The aim of this second lesson was to identify the tensions threatening, at the start of this century, the global public health paradigm that had become established in the previous century : an ageing population ; the persistence across the planet of areas that do not enjoy the same conditions of access to high-quality primary and hospital care ; a growing population of immunocompromised patients as a result of therapeutic advances such as multi-drug therapy for cancer and leukemia, and organ and bone marrow transplants ; multi-resistance to antibiotics and nosocomial infections ; vaccine mistrust and, of course, emerging viral infectious diseases. Added to these tensions is a new dimension, that of epidemic, non-communicable, post-modern diseases such as obesity, diabetes, asthma and atopy, chronic intestinal diseases of the gut and colorectal cancer, which respond in part to dysbiosis, i.e. alterations - particularly depletion - of our microbiota in response to environmental and lifestyle changes. The intestinal microbiota thus appears as a sensor, integrator and effector of our environment.