Influenza: Disaster Awaits?

Have you ever wondered why flu is still a thing? By which I mean, doesn’t it seem strange that we’ve got fabulous vaccines for measles, polio, rabies etc…. but for a virus that infects 5-15% of the population every year and causes about 250,000 to 500,000 deaths we only have a pretty shaky vaccine which has to be topped up and changed every season. Ever mused on why that is?

Influenza viruses are constantly changing in a bid to escape our body’s territorial army: the immune system. They do this in two ways:

1 Antigenic drift:

Small mutations in the DNA of influenza virus occur as the virus replicates over time. These small changes add up until the body’s immune system can no longer recognise the virus so well, and it can replicate stress-free. The key point here though, is that it’s a gradual, minor change.

Antigenic shift:

This is when two types of virus infect the same cell and exchange DNA to form a new type that the immune system won’t recognise. This typically happens when a human flu virus crosses with an animal flu virus, like bird or pig flu. This is a large and sudden mutation and most people won’t have pre-existing immunity – setting up the scene for a pandemic to occur.

So whilst antigenic drift is responsible for seasonal flu and has a vaccine which is only as accurate as our predictions from the southern hemisphere, antigenic shift is the real danger. The problem is that (unlike drift) antigenic shift doesn’t confer any cross protection (where the body recognises at least some parts of the virus and can mount an immune response) and the entire population is vulnerable.

Back in 1918, an unusually deadly influenza pandemic broke out, killing more than the total casualties of the first world war combined. The virus was of the H1N1 strain, which refers to the type of proteins sitting on the surface of the virus.

It’s recently been estimated that if the 1918 flu pandemic broke out today, it would probably kill more than 62 million people. To put this into perspective, an estimated 55.3 million people in the world die each year. The reason for this, despite the advances in modern medicine, is how influenza has evolved to spread rapidly throughout populations combined with the ease of global travel.

The most recent flu pandemic was the 2009 swine flu, which actually had the same H1N1 subtype as the 1918 flu. The world watched in horror as the newly discovered flu strain spread rapidly from its origin in Mexico across the Southern hemisphere. 

2000px-Swine_influenza_symptoms_on_swine-en.svg.png
Translated by B. Jankuloski. Original by Mouagip (File: Swine influenza symptoms on swine-en.svg) [Public domain], via Wikimedia Commons

The 2009 pandemic was responsible for 150,000+ deaths. This isn’t anywhere near the numbers of the 1918 flu, as luckily it turned out to be quite mild.

Current strategies for what to do in case of a new, even deadlier pandemic include a strong vaccination effort, antiviral drugs and combatting pneumonia (which some people are more vulnerable to after flu) with antibiotics.

Unfortunately, most of these mechanisms of protection aren’t really going to reach some of the poorer developing countries, which might enable the virus to gain global traction. What’s more, from past experience, normal supply of  antiviral drugs doesn’t tend to meet pandemic demand and brings with it an inevitable lag of supply and demand.

Other ideas include school closures and travel restrictions to try and limit contact between people and prevent the spread of the virus.

(Header image by Navy Medicine from Washington, DC, USA (09-5036-043 influenza) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons)

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Antibiotic Resistance and the Rise of the Superbugs

It’s a bit of a buzzword in the news recently: antibiotic resistance. I mean, yes, it is actually a pretty serious issue – and it does deserve the media hurrah it’s been getting… but is it solvable?

I think it’s best we begin with the idea that there are good microbes and there are bad microbes. Humans are made up of around 35 trillion cells, and are inhabited by (drumroll please) about 100 trillion microbes – an almost 3:1 ratio.

Just to clear this up, a microbe (or “microorganism”) is quite literally just a tiny tiny organism which is, in fact, so tiny that we can’t see it with the naked eye. They are some of the most ancient creatures inhabiting the earth, and include bacteria, archaea, fungi, protists and potentially viruses. I use the word ‘potentially’, as it’s still hotly debated whether or not viruses can be technically classified as alive.

What’s more, although microbes would probably be quite fine without us (and our pesky modern medicines), we would categorically be unable to exist without them.

We’re all familiar with the bad or “pathogenic” (disease causing) microbes: if you’ve ever caught a cold, or had a spot, or contracted food poisoning, you have them to thank. Usually these come from outside the body, but if the body’s natural order is disturbed then a useful “good” microbe can grow out of control and wreak havoc.

On the other side of things, good microbes can protect us by crowding out some of their dangerous relatives that can cause disease. They can help us digest our food, and can synthesise important vitamins for us.

So on to antibiotics.

Antibiotics are popularly prescribed drugs which work by altering things that bacterial cells have but human cells don’t. For example, penicillin stops bacteria from building it’s cell wall – a property that human cells don’t have. The key thing to remember here is that antibiotics only work on bacteria, and don’t damage your cells.

Now, unfortunately for us, the bacteria don’t just sit there and take it. The problem can be split into two parts: 1) the ability of bacteria to mutate their DNA and 2) their ability to pass on little packets of DNA to a neighbouring bacterium.

Mutations are rare and spontaneous changes in the bacteria’s DNA which can lead to many different types of “resistance” (which just means being able to evade the effects of antibiotics). For example, some mutations could let the bacteria develop useful chemicals called enzymes which can inactivate the ingredients in the antibiotic.

This results in a “selection pressure”: bacteria which can resist the attack are much more likely to survive and reproduce, passing on the helpful  gene and replacing all the bacteria which were killed off. In this way, pretty soon all the bacteria in that population will have the gene – and so the antibiotic will be rendered useless. This is called “vertical gene transfer”, and effectively means the genes are being passed down the family tree.

Antimicrobial_resistance_-_mutation
By NIAID [Public domain], via Wikimedia Commons

The other mechanism is called “acquired resistance” and works through a type of bacterial mating called conjugation. This is when bacteria can exchange genetic material encoding the helpful resistance genes, letting it spread through the population. This is known as “horizontal gene transfer”, as the genes are being passed from one bacteria to the next.

The overuse of antibiotics leads to a greater selection pressure, and so effectively we’re speeding up the spread of resistance in bacteria. In some countries and over the Internet, you don’t need a prescription to buy antibiotics, and some people use them to treat viruses…which they don’t actually work against.

A superbug describes a bacteria that has collected all these little packages of resistance, making it immune to a whole load of antibiotics. If the name MRSA sounds familiar, it’s because it made headlines a few years back as a big big problem in hospitals. Methicillin-resistant Staphylococcus aureus is a bacterial superbug which is resistant to many of the commonly used antibiotics.

The real worry is that one day soon a bacteria will come along and we just won’t be able to treat it. This could mean a return to the pre-antibiotics era – where you could go deaf from an ear infection, or even die from a throat infection.

It’s a pretty bleak looking future.

So what can we do about it?

Really, the only possible thing to do is to try to slow down our use of antibiotics so we can be sure they’ll still pack a punch when we use them. If you’re prescribed antibiotics, make sure you finish the whole course even if you feel better – or else the bacteria could become resistant. Agricultural antibiotic use should also be wound back a bit, as it’s helping to create these antibiotic resistant bacteria which can jump ship to humans, and cause even more problems. Many animals are pumped full of antibiotics to either make them grow more quickly or to prevent disease which, due to the living conditions, could rapidly spread throughout the farm… but is the trade-off really worth it?

The other point to mention is that antibiotics work against both good and bad bacteria. Yes, they help to kill off what’s making us ill, but they can also disturb the balance of our body in the process – which can lead to digestion problems, or increase susceptibility to infection. So it’s doubly important to only use them when really necessary, and to trust your doctor!

Below is a great video which sums up the causes of antibiotic resistance – give it a watch if you’re interested!

Unsuprisingly, Radiation and the Human Body are Not Best Friends

When people talk about harmful radiation or radiation poisoning, it usually conjures up images of deformed animals with two heads or a glowing green lump of metal.

But biologically speaking, what exactly is “radiation” and what does it do to our cells?

Well – let’s first think about one of the most dangerous nuclear disasters in the world’s history: the terrifying wall of water that crashed into Japan on the 3rd November 2011 and shocked the world.

An earthquake off the Pacific coast of Tōhoku had a whopping great magnitude of around 9.1 – to put this into perspective, the 2010 Haiti earthquake which claimed over 100,000 lives had a magnitude of 7. As a result of the 15 meter waves crashing into Japan’s east cost, three nuclear reactors went into meltdown at the Fukushima power plant, causing one of the largest releases of radiation in history.

I’m sure you’re all aware that a ton of radiation is not a great thing for the human body – hence why an estimated 97,000 locals have been barred from returning to the region and an exclusion zone of 20 km has been set up around the power plant. But what does this high dose realistically mean for your body?

Nuclear, or ionising, radiation can be thought of as a kid that’s just downed five cans of red bull and eaten a bag of sugar – and our DNA in this instance is the proverbial china shop. Unlike radiation from a light bulb or microwave, ionising radiation can knock off electrons from molecules willy nilly, which is bad news for the two metres of DNA coiled up in every cell in our body. The radiation is energetic enough to break bonds between atoms, or create highly reactive “free radicals” which can disrupt bonds in surrounding molecules. Effectively, you get a little energy packet bouncing around in your cells, causing quite a lot of damage.

The worse case scenario for a cell is radiation-induced death, which causes the immediate effects of radiation poisoning like nausea, swelling and hair loss. If you’re exposed to enough, your blood vessels burst and your immune system is killed off, leading to a much greater chance of infection.

Cells which are less severely damaged can still accrue harmful mutations – and not the cool “hey look my eyes are lasers” X-men kind. Mutations can disrupt the control mechanisms of cell division, causing a cell to replicate uncontrollably and become cancerous. This is, unfortunately, why infants in the most affected areas have a much higher risk of developing cancer when they grow up.

But Anna, I hear you cry, if ionising radiation is so terrible, what about the people who worked at the power plant normally – surely they’ve royally screwed themselves? Well, our body is actually kind of used to a certain amount of radiation – mostly from the sun, which constantly emits DNA-damaging ultra violet radiation. Handily, we have evolved enzymes (molecules which speed up chemical reactions) that can repair this damage as fast it can happen, keeping our risk of cancer mercifully pretty low.

But spend just one hour in radiation-soaked Fukushima, and you could exceed the lethal dose. So – how can you protect against ionising radiation?

Effectively, you either need to have inherited DNA repair enzymes from your parents that are in tip-top shape and can cope with a huge load of DNA damage, or (more realistically) you need to limit the radiation your body comes into contact with.

One of the most recommended things you can do is to pre-dose yourself with iodine pills. This is because the radioactive form of iodine is quickly absorbed by a gland in your neck called the thyroid. By taking normal iodine, it prevents the absorption of the radioactive form, which instead passes through you.

But in reality, the best advice I can give you is to get as far away as possible, as quickly as possible. If that’s not possible, barriers of lead, concrete, or water can absorb radiation, and are probably your safest bet.