QI: The Book of General Ignorance - the Noticeably Stouter Edition (32 page)

Yes, ‘germ’ is an informal term for any biological agent that causes illness to its host and so covers both viruses and bacteria.

Viruses and bacteria are quite different. Viruses are microscopic parasites too small to have cells or even their own metabolism. Their growth is entirely dependent on their host. Each infected host cell becomes a factory capable of producing thousands of copies of the invading virus. The common cold, smallpox, AIDS and herpes are viral infections and can be treated by vaccination but not antibiotics.

Bacteria are simple but cellular, the most abundant of all organisms. There are approximately 10,000 species living in or on the human body: a healthy human will be carrying ten times as many bacterial cells as human cells, and they account for about 10 per cent of dry body weight. The vast majority
are benign, and many are beneficial. Bacterial illnesses include tetanus, typhoid fever, pneumonia, syphilis, cholera, food poisoning, leprosy, and tuberculosis and they are treatable with antibiotics.

The word ‘germ’ comes from the Latin
germen
meaning sprout or bud. It was first used to describe a harmful microorganism in 1871 but it wasn’t until 1875 that Robert Koch finally demonstrated that anthrax was caused by a particular species of bacteria.

Thirty-five years earlier, Ignaz Semmelweis, a Hungarian doctor had set up the first hygienic hospital ward in Vienna General Hospital. He noticed that the death rate of poor women attended by the nurse midwives was three times less than that of the wealthier women attended by the doctors. He concluded that this was a matter of cleanliness – the doctors used to go directly from the morgue to the obstetrics ward without washing their hands. When he presented his findings, his fellow doctors rejected his theory, unable to believe in what they could not see.

In recent years, however, the hygiene itself has come under scrutiny. There seems to be evidence that indiscriminate use of anti-bacterial agents might have damaging side effects, allowing those bacteria that do survive to mutate into even more virulent strains. Also, our immune system, deprived of bacteria and parasites that it has struggled against for thousands of years, has a tendency to overreact leading to a sharp upswing in allergic diseases such asthma, diabetes and rheumatoid arthritis.

Despite this, infectious diseases still kill more people than anything else and 80 per cent of those diseases are transmitted by touch.

Most hygienists recommend that washing our hands regularly with good old-fashioned soap and water is the best and safest way to stay healthy.

It’s not stress or spicy food

Contrary to decades of medical advice to the contrary, it turns out that stomach and intestinal ulcers are not caused by stress or lifestyle but by bacteria.

Ulcers are still relatively common, afflicting one in ten people. They are painful and potentially lethal. Napoleon and James Joyce both died from complications connected with stomach ulcers.

In the early 1980s, two Australian pathologists, Barry Marshall and Robin Warren, noticed that a previously unidentified bacterium colonised the bottom part of the stomachs of people who suffered from gastritis or ulcers. They cultivated it, gave it a name (
Helicobacter pylori
), and began to run trials. They found that when the bacteria were eliminated, the ulcers healed.

Even today, most people still think that ulcers are caused by stress. The medical explanation was that stress diverted blood from the stomach, which reduced the production of its protective mucus lining. This gradually left the tissue beneath vulnerable to stomach acid and the result was an ulcer.

What Marshall and Warren were proposing – that a common physiological condition, akin to a blister or a bruise, might actually be an infectious disease – was unprecedented in modern medicine.

Marshall decided to become his own experiment. He drank a Petri dish full of the bacteria, and soon came down with a severe case of gastritis. He tested himself for the bacteria – his stomach was teeming with them – and then cured himself with a course of antibiotics. The medical establishment had been proved wrong.

In 2005, Marshall and Warren were rewarded for their tenacity and vision, winning the Nobel Prize for Medicine.

Helicobacter pylori
is present in half the human population, and in almost everyone in developing countries. It is usually contracted in early childhood and can stay in the stomach for life. It only leads to ulcers in 10 to 15 per cent of those infected.

We still don’t know why this should be, but we do know how to treat it.

Not nothing.

It’s not as useless as you’ve been led to believe.

The appendix is thought to be a remnant from the time when early humans ate grass. In other primates, such as gorillas and orang utans, the equivalent organ, known as the cecum or caecum (from the Latin for ‘blind’, as in ‘blind alley’ or dead end) is much larger and is used to digest the cellulose from the grass and leaves they eat.

But the human appendix has other more practical uses. Lymphoid tissue (which helps protect the body from bacteria and other foreign invaders) begins to accumulate in the appendix shortly after you’re born and peaks in early adulthood. There is some evidence that the appendix also ‘trains’ our immune system by producing small amounts of dangerous antigens, which stimulate the production of protective antibodies. More recent research also points to it
being a storage centre for helpful bacteria. Given the widespread prevalence of diarrhoea in the developing world (there are an estimated 1.4 billion cases a year), some researchers think its very shape and size make the appendix an ideal reservoir for repopulating the gut with essential bacteria after the disease has flushed the rest of the intestines clean.

The appendix can also act as a backup in reconstructive surgery. It has been shown to be useful if a patient needs reconstruction of the bladder; it can be used as a substitute sphincter muscle or fashioned into a replacement ureter (the organ that connects the bladder to the kidneys). For all these reasons, it is no longer standard practice for the appendix to be removed during abdominal surgery.

In anatomy, the term ‘appendix’ can refer to any section at the end of an organ. The correct name for the one we know colloquially as ‘the’ appendix is the vermiform (or ‘wormlike’) appendix. 

Not nothing.

It’s not as useless as you’ve been led to believe.

The appendix is thought to be a remnant from the time when early humans ate grass. In other primates, such as gorillas and orang utans, the equivalent organ, known as the cecum or caecum (from the Latin for ‘blind’, as in ‘blind alley’ or dead end) is much larger and is used to digest the cellulose from the grass and leaves they eat.

But the human appendix has other more practical uses. Lymphoid tissue (which helps protect the body from bacteria and other foreign invaders) begins to accumulate in the appendix shortly after you’re born and peaks in early adulthood. There is some evidence that the appendix also ‘trains’ our immune system by producing small amounts of dangerous antigens, which stimulate the production of protective antibodies. More recent research also points to it being a storage centre for helpful bacteria. Given the widespread prevalence of diarrhoea in the developing world (there are an estimated 1.4 billion cases a year), some researchers think its very shape and size make the appendix an ideal reservoir for repopulating the gut with essential bacteria after the disease has flushed the rest of the intestines clean.

The appendix can also act as a backup in reconstructive surgery. It has been shown to be useful if a patient needs reconstruction of the bladder; it can be used as a substitute sphincter muscle or fashioned into a replacement ureter (the organ that connects the bladder to the kidneys). For all these reasons, it is no longer standard practice for the appendix to be removed during abdominal surgery.

In anatomy, the term ‘appendix’ can refer to any section at the end of an organ. The correct name for the one we know colloquially as ‘the’ appendix is the vermiform (or ‘wormlike’) appendix. 

Sugar is fine. It’s bacteria you need to worry about.

Over 600 species of bacteria live in our mouths. With a single mouth hosting over six billion individual organisms, it isn’t surprising that some species (
Streptococcus mutans
chief among them) cause us problems. By feeding off the
sugars in our mouths, they create lactic acid as a by-product. It is this that eats away at our tooth enamel and causes cavities.

But bacteria don’t just eat sugar, they’re happy to feed off any kind of starch. The foods that are worst for your teeth are hard-to-shift carbohydrates. Unlike sugars that dissolve quickly in your saliva, cooked starches, particularly potato products such as crisps, cling longer to the teeth, meaning that more acid is produced. Raisins are also particularly good at finding clefts and pits to hide in.

And if that isn’t good enough news for the confectionery industry, research from Japan’s Osaka University in 2000 discovered that the husks of the cocoa bean contain antibacterial agents that can protect against tooth decay. Enough of these are present in chocolate to make it much less dangerous for your teeth than other high-sugar foods. So next time you’re besieged by infants in a till queue, you’ll be doing them a favour by loading the trolley with sweets and chocolate and holding back on the crisps and doughnuts.

Dental caries (tooth decay) is the most widespread and common human disease in the world. Ideally, to prevent it, all we need do is brush our teeth after every meal for at least two minutes, to remove all remnants of food from our teeth.

People with gum disease are almost twice as likely to have coronary artery disease than those without. This is because bacteria from the mouth can find their way to the heart, causing blood clots.

According to statistics compiled as part of the 2007 National Smile Week, the UK’s dental hygiene is getting worse, not better. 12 per cent of Britons brush only ‘a few times a week’ or ‘never’; fewer than 30 per cent say they brush for two minutes and 60 per cent of people claimed they would happily share their brush with their partner, child, friend or favourite celebrity. Flossing habits turned up a wide variety of
utensils, including drill bits, twigs, fish bones, shoelaces and toenails.

Despite this, the number of people having their teeth completely removed has fallen dramatically. In 1968, 36 per cent of the population had false teeth, today fewer than 12 per cent. During the 1940s and 50s, the replacement of all one’s teeth with a new set of dentures was a common and popular twenty-first birthday present, particularly for women. They looked regular, stayed brilliantly white and were much easier to maintain.