04.28.09
Microevolution and swine flu virus
Analysis: Caution, not panic is best approach to outbreaks
WE DO not yet know what exactly the colours of this virus are. The worst-case scenario is that it is already a pandemic strain and it is spreading.
It has not done this yet. We have seen just a few thousand cases in Mexico city with a population of 25 million people.
So it has not spread anywhere near what would be considered to be of pandemic proportions as of yet.
If in the next week to two weeks it starts to spread more widely, we will know we have a pandemic.
Otherwise, it could just fizzle out – it may not be a fit virus to maintain a pandemic.
Another scenario is that it is not a pandemic strain, but is still capable of carrying on and mutating, reinventing itself as a pandemic virus in the next six months or so.
The strain could pick up the ability to improve its fitness to spread.
There is an immediate short-term need to look at this virus, but there is also the possibility that it will retrench and have another go ate becoming a pandemic strain in the future.
Whether this strain is able to mutate is purely down to chance – it is what Charles Darwin spoke about.
There could be random mutations which lead to the right permutation to create a deadly pandemic strain.
Flu has only done this three times in the last 100 years so it is a rare thing to happen, thankfully for us.
There is this possibility of mutation but I think it is too soon to panic.
The virus does not really seem to be taking off that quickly in Mexico.
We should be worried, but not to the extent that we start to panic.
We will still need to be looking for a vaccine and stock-piling antiviral drugs.
We need to make people aware of what they can do to limit their chances of picking up an infection.
Flu is good at adapting and finding ways of getting past our armour.
But it is still a complex organism. It still has to get all the genes lined up and synchronised with each other, doing the right thing, before it is a really fit virus to spread and then become a dangerous pandemic strain.
We hope, in the case of the swine flu currently being seen in Mexico and elsewhere, that it will simply fizzle out.
But there will be a pandemic sooner or later. This might not be it, but it will come – we just do not know when that will be.
• Professor Nigel Dimmock is emeritus professor of virology at the University of Warwick.
Bo Thompson said,
April 28, 2009 at 4:16 pm
In 1918:
In large U.S cities, more than 10,000 deaths per week were attributed to the virus. It is estimated that as many as 50% of the population was infected, and ~1% died. To compare, in “normal” (interpandemic) years, it is estimated that between 10-20% of the population is infected, with a .008% mortality.
The fact the current ‘swine flu’ has shown to be contagious is alarming. So far the virus has shown to have a 6% to 6.3% mortality rate. It may not seem like much, but please consider the following: The deadly influenza panic in 1918 had a mortality rate of under 1%.
This virus went on to kill tens of thousands of healthy people a day in large cities and up to 100 million people world wide.
Viruses, like this strain of swine flu, kill their host by over-stimulating active immune systems that are robust and healthy. That is why the victims in Mexico were between the ages of 20 and 45.
Some have said that no one in the United States have died from the virus, so we need not worry. Experts say it is only a matter of time. The virus is not prevalent enough to reach statistical significance in the United States, with only a handful of confirmed cases. 93.7% of all Mexicans with the virus recovered.
More cause for worry: The 1918 virus started off ‘mild’ before it mutated into a raging storm. It also does not mean we will see millions of deaths. It is too early to draw sweeping conclusions. Nevertheless, there is potential for a disastrous pandemic. If 50% of Americans catch this flu in the next two years, and the mortality rate stays at 6.3%, we would witness 20+ million deaths.
This strain of virus is more potent and more deadly than the virus that hammered the world in 1918 and 1919. Viruses come in waves. There are striking similarities to this virus and the virus that killed up to 100 million people in 1918. The first wave is historically more mild than the later waves.
In addition to this virus becoming more severe, it is mutating faster than previous virus that we have seen. In addition, this virus is nothing like we have ever seen before because it combines features from viruses natural in different parts of the globe. We are in uncharted territory.
If it follows the same path as the 1918 flu, we will see very damaging results. However, we must remember we are a global society now and the virus can spread quicker than we have ever witnessed in history. This is very concerning especially since the drugs we have now seem resistant.
While there have been no deaths in America, it is shadowed by the fact the common variable among the deaths seem to be age. While most American cases have involved the very young and very old (under 10 and over 50) the Mexican cases that ended fatally involved the robust and healthy (over 20 and under 45).
This virus kills the host by over-stimulating the immune system. The term that is used when the immune system over reacts is called a Cytokine Storm. It is usually fatal. During this “Storm” over 150 inflammatory mediators are released. This would account for the high mortality rate in 1918-19.
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