This follows my previous comments on the skin and its secretions. As ‘civilised’ animals we are obsessed with cleanliness. We shower or bath ourselves daily and even more frequently, using detergents and powerful chemicals to remove dirt, skin debris and secretions; we wash our hands after the slightest contamination; we disinfect kitchen surfaces, floors and our clothes obsessively to kill ‘germs’, and so on. And despite all these efforts, we do not manage to avoid skin diseases, respiratory infections, allergies and asthma, food poisoning and so on. An ever-increasing problem is the transmission of bacteria and parasites which have become resistant to treatment. Yet we continue to believe we can protect ourselves from all the organisms which surround us. This belief is encouraged by the manufacturers of the products we rely on for our ‘safety’.

However, despite all our precautions, we are in frequent contact with a wide range of bacteria, fungi and parasites. They are in the air we breath, on our food, in our clothing, bedding, and on all the surfaces we touch. And then, of course, there are all the friendly bacteria on our skins (even after washing), in our mouths, ears and other orifices and, as pointed out previously, in our intestines, especially the colon. Animals don’t take daily showers, disinfect themselves, wash their food, clean their teeth with toothpaste, yet they remain largely free of many of the diseases we develop. There is a lot of evidence that our natural fellow travellers, which have evolved with us over many thousands of years, can prevent us being attacked by serious pathogens. It is time we gave them more respect.