Bonnie and Clyde – eggs can be killers.

Pretty soon, the most coveted dinner party guests will be microbiologists. If you know any, you should cultivate them. Germs are coming back into fashion.

A lot of people have problems accepting that humans don’t contain any rare or precious elements, except metaphorically, like pearls of wisdom. No gold inside us, no platinum, no diamonds. No titanium, amber or crystals. Mostly water and cheap stuff, like carbon, nitrogen, sulphur and rust.

But there’s worse to come – a large part of us is not human at all – we are nine tenths made of bacteria – at least in terms of the number of cells. The gut ‘microbiotica’ is our largest organ, and possibly our most intelligent one. If the human body is run by a board of directors, the brain might be chairman, but the largest stakeholder is the colon. Definitely not a silent partner. Scientists have shown that the communication network between the gut and brain is a superhighway, the vagus nerve being the M1-near-Luton of all nerve pathways. Many neurotransmitters exist in the gut as well as the brain, and many of them were found in the gut first, such as cholecystokinin, a peptide hormone.

For decades, people were brought up to believe germs were the bad guys. After all, millions of people used to die of infectious diseases like cholera and tuberculosis, and these diseases are still prevalent in much of the world. Although such diseases are controlled mainly by public health measures rather than antibiotics, there is an awareness that resistant organisms are threatening to launch another era of infectious diseases. Already, there have been massive problems controlling outrageous punk – rocker organisms like clostridium difficile (the clue’s in the name).

I’m going to just introduce the phrase ‘faecal transplant’ and get it over with. But that’s how clostridium difficile can be treated. And that’s why there’s a website called ‘the power of poop’. The cure for bad bacteria is good bacteria. I don’t want to upset any readers who are germ phobic, though I expect they are already spraying dettol over the touchscreen and putting on a new pair of Marigolds. A small number of germs have got the others a bad name, just like badgers. We are going to have to stop killing them and start hugging them more. We will see a revolution in the yogurt industry similar to the real ale phenomenon of the seventies. Instead of Ski type products that have been sterilised and given an absurdly-soon sell by date, we will have yogurt with a bit of fizz to it with a ‘best after 2016’ label.

It’s been a while since I treated someone with a germ phobia, but I have a lasting memory of standing next to someone in their home, both of us with our hands pressed against the slimy surface of a kitchen sink, keeping them there for 20 minutes, time for anxiety levels to die down, doing some hands-on behavioural therapy. On this occasion I realised why Cognitive Behaviour Therapy was taking over – because it could provide a massive short cut. Rather than change the actual behaviour, why not look at the thinking behind the behaviour instead? This lady thought that even one germ could kill you. So, hands still pressed into the slime, we talked a bit about the germ theory of disease. People tend to assume that germs cause diseases by infecting people. This is only partly true, in that we have a powerful immune system, so that even the most aggressive organisms will not cause illness in everyone, or even a majority of people. There has to be a chink in the immunological armour, plus a sizable number of germs in the infective boarding party. This concept is called the minimum infective dose, which is usually millions of bacteria. One germ is hardly ever enough to cause an infection. In fact, landing on a human body is one of the worst things that can happen to a germ. It’s equivalent to being the first person up the ladder in an attempt to storm a castle. There are many kinds of immune response, equivalent to boiling oil. So that’s what I told her. It’s true that people can still catch cholera or tetanus, but statistically the chances of catching anything lethal from a sink in Edgbaston is national-lottery-level low (south of Hagley Road, anyway).

The problem for today though, is how to take a rational position on personal hygiene. Last week, at the seaside, I saw a child drop the ice cream out of a cornet onto the beach, only to be retrieved and replaced on the cornet and given back to the child without even a wipe. The child appeared to accept this without reaction or comment. Was the parent doing the child a favour in terms of building up immunity, or recklessly courting a nasty infection? Luckily, most germs will not get through the multiple defences of the upper GI tract, like the concentrated hydrochloric acid in the stomach. That seems to be a problem for so called macrobiotic remedies, which often fail to reach the minimal infective dose. Food outlets are stringently controlled for hygiene. In our cafe shop for instance, the volunteers had to put on plastic gloves between touching the food and the money, which slowed them down enormously, particularly if they had impaired fine movement.

This week however there has been renewed interest in raw milk, even suggesting that it may have health benefits long term. Yet, googling ‘raw milk’ suggests that it’s one of the most dangerous groceries, up there with eggs, peanuts and cantaloupes, in the food-borne infection league. All this makes it difficult to know what to tell germ phobics, in terms of psycho-education.  Recently a microbiologist told me not to eat potatoes that have gone a little bit soft or started sprouting. Apparently, they can contain very dangerous toxins. I confess, I never suspected the humble potato could be a mass murderer, though I was not surprised about cantaloupes, whatever they are.

People’s attitudes and behaviours around food hygiene seem to vary tremendously. Some of it comes down to ‘locus of control’ issues, and general perceptions of environmental threat. In the absence of a testable consensus on hygiene, we might just have to go back to old school marigolds-off behavioural therapy. If it turns out, as seems likely*, that ‘good bacteria’ can treat a range of diseases, possibly including Depression, some very careful marketing is going to be needed. For instance, the corporate colour scheme should definitely not be brown. It’s just a gut instinct.

* Dinan TG and Cryan JF, 2013, Melancholic Microbes: a link between gut bacteria and depression.  Neurogastroenterol Motil, 25, 713-719