Common sense on swine flu

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The swine flu virus is now unstoppable, according to the experts. We’re no longer in the prevention phase – treatment is now the name of the game.

Flu has been suspected or confirmed at a number of schools, among ball girls and boys at Wimbledon and at Glastonbury. Yet, despite the preponderance of flu stories in the news, confusion reigns.

A number of supposedly knowledgable newspaper columnists have been writing about use of antibiotics, which is a nonsense, as I’ll explain. And many people are also in a jumble as to the difference between swine flu and regular flu.

As is often the case, the best way to get your brain around what’s going on is to head back to basics.

What is a virus anyway? And how do these pestiferous entities make you ill?

Viruses infect all known forms of life – humans, insects, plants, fungi, everything. So it’s ironic that people might consider treating viruses with antibiotics. Antibiotics kill bacteria – and even bacteria aren’t safe from viral infection.

Viruses – perhaps obviously – don’t form fossils, so we can’t study their early evolution, but they have probably existed ever since life itself first evolved.

Strictly speaking, viruses are not alive, unlike bacteria.

They do not respire or respond to outside stimuli, nor do they move or grow, which are among the requirements to be considered living things. Viruses are generally viewed as organic structures that interact with living things.

They were first discovered by scientists in the late 19th century who were working with filters with extremely small pores. Bacteria are rather large – at least on the kind of scale that microbiologists think in – and couldn’t pass through the filter.

But at that time bacteria were the smallest known agents of disease, so scientists were confused when they strained infectious extracts and they remained infectious.

Initially they thought that viruses were some sort of liquid, which was later disproved. It wasn’t until the 1950s, when the hugely powerful electron microscope was invented, that scientists got their first glimpse of these quasi-creatures.

If you’ve never seen a high-power image of a virus, take a look at some on the web – they’re both fascinating and bizarre.

‘Given the life cycle of a flu virus, it’s no wonder they make you ill. The way they operate is like something straight out of science fiction’

Some are long tightly coiled spirals, which can be either rigid or bendy. Some are round and blob-like. Others are surrounded by a fatty envelope derived from the unfortunate host, such as the flu and HIV viruses. Some even look like something from outerspace, with an icosahedral form – which for those of you who like your ancient Greek means a 20-sided three-dimensional shape.

However, the main virus structure is really rather simple. They are made of several protein subunits surrounding a molecule of either DNA or its close relative RNA.

The flu virus has two main proteins which stick out like spines on the outside of the virus – haemagglutinin (H) and neuraminidase (N), which are the basis of how the flu viruses are given their intimidating names.

There are 16 different types of H and nine types of N and it’s the combination of different types that lead to the names H1N1 (swine flu), H5N1 (bird flu) and a host of other flu types.

Viruses evolve by two different processes, known as antigenic drift and antigenic shift.

Drift, which involves gradual and subtle changes to H and N, is responsible for the ordinary type of flu that spreads every winter.

It’s shift that’s more of a worry. Shift involves sudden changes in H and N, which means that people have no immunity and are unable to fight the virus off easily. And it’s antigenic shift that’s led to the rise of swine flu.

Given the life cycle of a flu virus, it’s no wonder they make you feel ill – the way they operate is like something straight out of science fiction.

Think of your own body, made up of millions of cells. A virus will attach to the outside of a cell, then penetrate it. The outer protein coat falls apart and the virus DNA hijacks the cell, making thousands of copies of itself inside. Finally the host cell bursts, sending the virus copies flying and killing the host cell in the process.

Fortunately, it’s not all viral doom and gloom for the world right now. The last couple of pieces of terminology to get your head round are infectivity and virulence, which are often confused. Infectivity refers to how easily a virus can catch a hold of its host. Virulence is how ill the virus makes you feel.

At the moment it seems that swine flu, although infectious, is not highly virulent. Even though the swine flu virus is spreading fast, the three people in Britain who have died all had underlying health problems.

So, while the virus might be unstoppable, it’s not time to get too frightened just yet.