If aliens were to examine a human, they would think we were just slavish organisms designed to feed microbes and carry them around. Our bodies contain ten times more bacteria than cells , and there are an estimated 3.

In 2012, about 8.2 million people died of cancer making the disease a major cause of death worldwide. According to the WHO World Cancer Report 2014 , this figure is expected to rise within the next two decades.

“Antibiotic resistance threatens a return to the pre-antibiotic era”. The World Health Organisation uses this strong expression when referring to a phenomenon that is rapidly spreading: the increasing resistance of microorganisms to antimicrobial medicines, such as antibiotics .