Swine Flu

WHO has decided to stop referring to the new influenza virus as ‘Swine Flu’ for the technical and more accurate Influenza A H1N1. If you want why this name is more accurate just keep reading.

In Biology classes at school we used to draw cells as a circle or oval with smooth surface. But a close-up on any cell would reveal that its surface is far from being smooth – it’s rather very bumpy and spiky (see how they look in the drawing!). These protrusions or spikes are the only reason that would make the word ‘Immunity’ have any sense, as they are the tool by which a microbe recognise which creature it will attack an on the other side will let – for instance – the cells of your body tell friend from foe from the trillions of entities they come across. This makes the spikes stand as the ‘5 senses’ of any cell.

The influenza virus then, like any other creature, recognises its victims through these spikes, and through them also does the immune system of the victim mounts a suitable strike. The 2 main types of these spikes are given the initials H and N, and from the H there are 15 subtypes while from the N there exist 9.

From the combinations of the Hs and Ns arises 3 families of influenza; A, B and C. The families B and C are only concerned with humans and they are stable which makes their infection mild and would not qualify them to cause any outbreaks. Family A is the one that is really troublesome, because they can infect several creatures other than humans and because their sleazy habit of shifting and drifting ( I had written a detailed post about this habit).  

Influenza A viruses are very unique from their peers. They continuously do changes in the shape of the surface spike, which would not jeopardise their ability to recognise their victims but would only compromise any previous recognition that a victim’s immunity has gained from previous exposure. That’s why you don’t get life-long immunity after getting the flu (which differs from what happens after infection from the less clever measles virus). And also this is what makes a vaccine for influenza only seasonal; because the immunity it gives you against this winter’s flu will be useless against the ‘slightly different’ flu virus of next winter.

But this is not enough to cause an epidemic, because these slight differences are quickly recognised by your body and in a few days all the fever, cough and muscle pain goes away (except in those with weak immunity of course). The influenza A viruses have a very strange capacity. Various types of viruses can invade the same cell. This usually happens in pig farms and the scenario goes as such…A human with a strain of influenza A transmits the virus to a pig. The same unlucky pig gets another infection from, say, a bird or a dog with a different strain. This pig acts as a mixing vessel. So an H5N3 coming with an H1N1 can give a brand new H5N1 (the combination rings any bell?). This is called a shift because a totally strange virus with a brand new combination is produced and this is what makes it capable of infecting huge amounts of people (or animals) in different places and killing many of the victims.

For the H5N1 virus, it primarily infected and killed poultry, and that’s why it was correctly termed avian flu. As for the current virus, it looks to have had acquired its H from a virus that infects pigs in North America, while the N resembles that in a virus from European pigs. But all the cases discovered were in human beings and that’s why it is not accurate to call it ‘swine’ flu. It’s important to add that this is the first arrival of H1N1. In fact, the most notorious and aggressive flu epidemic in 1918 (that killed from 50 to 100 millions) was an H1N1. But the current virus it quite different from its the older brother because, as I said the spikes Hs and Ns are always changing, and the combination of these 2 specific ones is what’s causing the problem.

It looks now that the best way to deal with the new outbreak is to try avoid catching the virus. All news footages show people wearing masks. This is a nice article about how useful this is. Simple measures as covering the mouth during coughing and washing hands regularly can be magical. Also seeing a doctor with any suspicious symptoms (fever, coughing, severe tirednss, headache and specifically with this one vomiting and diarrhoea) is very important. It’s said that the tamiflu that worked with avian flu should work with the H1N1 (but this yet is to be proved).

But why not have a vaccine? It should be the best defence. It should be, yes, but it isn’t. It will need some 4-5 months to appear which is very late. Scientists say that the same difficulties that faced them in developing a vaccine for avian flu persist in this case.

The first step for preparing the vaccine is to extract the genes of the virus that are responsible for making the H and N spikes. These genes are then implanted in another harmless virus that will be able to have these spikes on its surface without having the capacity to destroy the cells of the lung. When the new virus is injected in an animal it will induce its immunity to make antibodies against these spikes that will render the vicious virus blind if it comes, and will also point the eaters of the immune system to clear them. The problem that arose with the Avian flu virus was that when its genes were incorporated in another virus, that new virus always failed to incite production of enough antibodies which requires using huge doses which makes the whole thin not practical because laboratories will be unable to mass-produce enough amounts of the vaccine. So for the time being just rely on yourself and follow the rules of prevention.