Norovirus

I wrote a piece in 2013 for a certain newspaper. The piece was never published; I can't remember why not, but it is a newspaper that is known for over-commissioning (and paying decently for killing anything). Here is the article, dug up by chance from a rarely visited folder.


On a recent Holland America cruise around South America, the liner’s captain had another job besides checking the radar, charts, passage plan and icebergs, and safely keeping afloat several thousand people. Nearly every announcement he made ended with a plea for people to wash their hands. It was so common that if he didn’t say it, passengers listening would fill in the gap, as a chorus: “…and now wash your hands.” He was right to do this: cruise ships are regularly swamped with negative publicity after yet another norovirus outbreak, but they are to be pitied: any closed, intimate space where people sleep, eat and have contact with each other is the favourite playground of this most effective infectious virus. Hospitals, schools, playgroups, ships, the office you are reading this in: it thrives in them all. It’s just that outbreaks are more visible and quantifiable on a massive floating petri dish like a ship. The captain was following hygiene protocols that any sensible cruise ship now follows but his enthusiasm for reducing infection sounds like he went above the call of duty. He was not just the Master and the Old Man, but Chief Sanitarian.


We don’t use the word “sanitarian” any more although we should. In Victorian times, it was a prestigious role (so was “sewage doctor”). Charles Dickens was a proud sanitarian, as was the journalist Henry Mayhew, who once met a woman in Bermondsey in the middle of a cholera outbreak who said, “neither I nor my children know what health is.” But the greatest sanitarian of all gets far less applause than he deserves. Celebrations have recently been held to celebrate 150 years of the London Underground, and rightly. But praise for the man who built part of it has not been forthcoming, although he deserves it even more than the engineers of the Northern Line or Oxford Circus. Sir Joseph Bazalgette built the Victoria Embankment, but he also built an astonishing sewer network that helped to add decades to our lifespan. Before the sewers were built, cesspits were emptied into the Thames, and people got their drinking water from the same source. Cholera came regularly, and one in two children died, most from faecally contaminated food and water. When flush toilets, sewers and hand-washing with soap became the norm over the next few decades, child mortality dropped by a fifth. That’s why the readers of the British Medical Journal, asked in 2006 to vote for the greatest health invention, chose the toilet.


Thanks to sanitarians like Bazalgette, we now live in the era of hygiene, and should be thankful for it. Elsewhere in the world, where there are no sewers or toilets, diarrhoea is deadly, and still kills more children worldwide than HIV/AIDS, measles and TB put together. But hygiene is not a magic force-field. It has to be created. And we are not always very good at it, as a ludicrously simple virus shows us.

Norovirus probably first entered official medical history in 1929, when an American paediatrician named John Zahorsky noticed a gastro-intestinal infection he called “winter vomiting sickness,” because it was winter and it made people vomit. He thought it was probably a contagious virus, but not until outbreaks in Norwalk, Ohio was it named Norwalk virus. In 1992, the International Committee on the Taxonomy of Viruses gave it the name we know and don’t love. At least, most of us don’t. Microbiologists can’t help but have respect for something they call the perfect pathogen. Norovirus is a mighty adversary because it is persistent, durable, canny and powerful. It infects us because it has to: viruses reproduce by invading human cells, then making sure that they get expelled in diarrhoea or vomit, to infect another host. That’s not difficult for two reasons: norovirus is efficient. It can infect with only ten particles, although each millilitre of fluid that you expel while infected can contain 11 million particles. Once you are infected, your excrement can keep shedding it for months. Standard alcohol hand gels used in hospitals don’t eradicate norovirus. It can lurk on soft surfaces for nearly two weeks; and if it gets into water and infects shellfish, it can live in them for years. You get immunity when infected, but it doesn’t last long. The shape of our modern food industry doesn’t help matters: Last September, 11,000 German schoolchildren were infected with norovirus traced to frozen strawberries. The strawberries had been fertilized with sewage effluent, a common practice in Germany and here. Schools that simply thawed the strawberries were infected; schools that boiled them weren’t.


The other reason is our weakness. Like many other human afflictions – at least 50, including dysentery, cholera and giardia - norovirus travels by the faecal-oral pathway. Scientists sometimes helpfully translate that as “poo to mouth” but here’s another translation: dirty hands. Despite soap, clean water and toilets, despite shelves of anti-bacterial products (useless against a virus, incidentally), norovirus has no trouble reproducing, because we are dirtier than we like to think. The London School of Hygiene and Tropical Medicine does regular studies of hand-washing rates, and its results are never comforting. Last year it found that 14 per cent of banknotes are covered with faecal particles, and a quarter of all British hands. Another year it tested hand-rails on tube trains. Filthy. Once, it found that 40 per cent of its own students didn’t wash their hands after the toilet. Only when the surveillance was announced by email did hand-washing rates double. Even faced with scary epidemics, people don’t change their dirty habits. A study by Harvard found that only half of people in the middle of a swine flu epidemic washed their hands despite countless public health appeals to do so.

Perhaps it’s because they think it’s a losing battle. I started counting how many potentially infectious surfaces I touched this morning but gave up after 40 or so. Perhaps we think it is benign: it is rarely fatal. That must be why I have heard young people boasting that they have come to work despite having norovirus. It wasn’t because they were unable to take sick days – although this is true for far too many people – but because they felt immune. They felt above infection because they couldn’t see it. But faecal-oral pathways and sloppy hygiene are behaviours that can spread all sorts of other, nastier infections. Cleaner hands reduce the spread of clostridium difficile, MRSA, flu, even cholera.


What can be done? Humans don’t respond to health messages or nagging. The best sanitarians understand that cleanliness and dirt are as much about software – psychology - as hardware (a toilet, an alcohol gel). A paper towel is only useful if your brain tells you to wrap it round the dirty toilet door handle. So the best sanitarians think laterally. The soap companies understood this, after years of trying to sell soap as a health improvement. Once they started marketing it instead as something that could make you sexier, sales soared. In India, where 750 million people still don’t have a toilet, one of the most powerful ways to persuade them to install one is for brides to insist on one before they will marry. This is known as “no loo, no I do.” The technique works everywhere. In 2009, another hygiene survey flashed electronic messages at the entrance to service station toilets. The messages included ‘water doesn’t kill germs, soap does”, ‘dirty soap dodger,” or “soap it off or eat it later.” Neither the hectoring nor the health message worked. (The disgusting one worked better on men.) But the most successful was the one that read “is the person next to you washing with soap?” Shame, social pressure, one-upmanship: any weapon will do against the invisible, powerful norovirus.


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