Not all the microbes that live on us or inside us are benign, and it is only thanks to the superhuman nature of our bodies that we survive constant attack. However, humans are becoming increasingly vulnerable to disease. This programme examines the dramatic increase in allergic diseases such as asthma, eczema and hayfever. One explanation of this is the 'hygiene hypothesis' - the body's immune system overreacts with these allergic diseases because of insufficient exposure to everyday dirt. In fact, exposure to bacteria can actually save lives and the programme features a brain tumour being treated successfully with the Herpes Simplex virus.
