Mycobacterium vaccae, a bacteria present in the mud of Africa, could revolutionise treatment of immune system disorders, proof that germs have therapeutic properties essential to our survival. Germs have always had a bad reputation. However, these micro-organisms are for the most part inoffensive. Some are even vital for our health. Today, many scientists, including John Stafford, a professor at the University College of London, believe that the lack of contact with certain bacteria may be at the root of disease. Professor Stafford noted that certain populations in Africa were naturally protected against leprosy and tuberculosis, two diseases caused by pathogenic bacteria. He highlighted the role played by another, this time inoffensive, bacteria in natural immunisation: M. vaccae. Present in the mud on soils in Uganda, this bacteria has since proved its efficiency in treating and preventing many other diseases such as asthma, psoriasis and even cancer. Our modern societies have for a long time avoided contact with germs. Today, many sufferers can start out on the road to being cured thanks to them!