Professor John Stanford, a bacteriologist, explains why exposure to germs is so important
The idea that germs are bad for us came out of the early part of the last century when there was a lot of concentration on teaching people about bacteria and the germ theory of infection.
The scientists that became most certain that all germs are bad for us, according to Prof Stanford, were the pharmacologists who were developing drugs specifically to kill germs and this was built on by people selling disinfectants and other household products. But Prof Standford says that in fact the really important ones that you need to kill are a very small number amongst the great majority:
"When you start as a bacteriologist you learn about the organisms that cause disease. As you progress further in your knowledge of this, you realise that there are many close relatives of the organisms that cause disease which are in your surroundings and it’s by meeting these that you develop protection. The hygiene hypothesis is part of a story of increasing separation from our environment and also that the environment has itself changed. And the two things together have resulted in our immune system not getting the essential learning processes that it really needs".
"Just as when you are a small child and you learn languages and your brain is important in the way in which you learn languages, then silently and behind the scenes, the immune system is also learning. But it learns from the things that you inadvertently need. The things you eat, the things you swallow, the things that gets into cuts, the things that get into your eye, almost any place where you have direct contact with the environment, the immune system learns from it."
Prof Stanford believes that it is not just that we separate ourselves from the environment by washing off the environment or by being careful not to touch dirty things, it is basically the way in which we no longer contact the general outside environment at all. Children today watch television a lot of the time and play with computers a lot of the time. There are many pressures which prevent children from being able to go out and play outside as they used to be able to do.
Prof Stanford's research over the last twenty years, was started off aimed at treating tuberculosis, preventing TB, improving the treatment of leprosy, preventing the children of leprosy patients developing the disease as they grew older. However, he says that the way in which it has progressed as been quite surprising:
"As we were beginning to understand the immune changes that we were capable of inducing, the scale and the scheme for this was very much greater. Today we’re very much interested in the prevention and potential treatment of cancers and in the prevention of allergic diseases. My current dream is that we can develop a vaccine which will replace the effects of too much hygiene and keeping ourselves too far away from the environment.
Yes, there are germs that are bad for you but the great majority of them are not bad for you at all, others that are neutral and others are definitely there and benefit you. This may seem like heretical to many people but if you work in this field it is not heretical at all, it’s what we’ve all come to learn to believe."
First broadcast: Friday 11 May 2001 on BBC TWO