Spanish Flu: a warning from history


Perhaps until recently, Spanish Flu has
been what some people call a “forgotten pandemic.’ But it was a huge global
calamity. In terms of the number of deaths we’re saying 50 to 100 million –
far greater than the casualties of the first world war. Roughly around May, April May 1918 when you know the carnage of the First World
War is is graphic and horrendous but at the same time this this unknown enemy is
starting to sweep through the US, Europe, the trenches and it is recorded by the
Spanish press and it becomes dubbed as the ‘Spanish flu’ because they are
neutral. Well at the time in the 1920s they estimated that maybe 20 million had
died. By the late 20th century that figure it went up to 25 million. In the
21st century with scientists and historians now getting together to work
much more closely, that figure has now been upped to fifty to a hundred million
people killed. This virus killed more people in the first 25 weeks than
HIV/AIDS has killed in 25 years – horrendous! Those mortality
statistics are staggering. We don’t know exactly why some flu strains are much
more severe than others and why some of them would would be more likely to kill
people or cause very severe disease. What is particular about avian and pandemic
viruses is that they replicate deep inside our lungs.
When our cells detect this they trigger very strongly an immune response this
leads to an influx of white blood cells and fluids into our lungs and it
restricts the amount of air space that we have to breathe. The symptoms are very
graphic and very very striking so you know it’s said that some people drowned
in their own phlegm, so if it was hitting or effecting
the lungs – people were spurting blood from their ears and their noses.
Descriptions of people turning blue or purple so you know it was really really
severe and people just dropping down in the streets Those that succumbed to the
flu were in the age group 20 to 40 years which is very unusual for an influenza
epidemic or pandemic and scientists and historians are now still looking to see
why. There’s really two ways that people died in 1918 they either died from the
initial flu infection or they died from a enormously strong immune response to
that virus were their lungs just filled up with fluids from trying to attack the
virus that got into their lungs. So traditionally everyone sort of said
oh well it’s the trenches you know the conditions of the war and that’s why it
was so fatal but when you think well you know how did it spread so rapidly around
the world to places that are not part of the theatre of war. I think the traditional explanation is it starts in Kansas in an army camp and then the
troops bringing it over to the trenches, Europe but there’s still so many, many
unknowns. So mathematical modelers have long been interested in the 1918
pandemic and one of the questions is to try and disentangle how its spread
around the world and exactly what the routes have been. Given a perfect data
you could work backwards and try to infer where it’s come from. Whereabouts
does it arrive in a country, does it arrive multiple times or thinking about
multiple countries where is the first place? If you understand the origin of a
pandemic then you understanding about where it’s come from
and maybe you can stop that in future. Almost certainly it was a bird flu
originally but then we also know that that flu or something very similar to it
was in pigs at the same time. Maybe it’s somebody who works very closely with
birds or who works very closely with pigs or has some other exposure like
that. One of the big really open questions in
flu research and flu Public Health is – How does the virus adapt from one
species to another, how does for example a virus in pigs or in Birds get into
humans and then start transmitting? Then the key question is – how does the virus then adapt within that person to stop being a pig virus or a bird virus and
become a human virus? in other words to be able to transmit from human to human
and it’s probably some very quick evolutionary process that is going on
within that human and in many cases won’t be successful, but in a few cases
we’ll and that’s when the virus can start spreading between humans and
become a flu pandemic and then stay in humans as regular seasonal flu. Just as people were celebrating Armistice Day and there was hope that it was dying
down but then it resurged and a far more deadly and virulent strain emerged. So this the second wave really spread like wildfire affecting a third or quarter of
the population of the world and it was short-lived so it petered out not long
afterwards maybe in 1920/1921 but it was it was in the sense short-lived. What happened was is that virus continued to transmit among humans, in fact it
continued until 1957 to transmit between humans and probably what happened there
is that the virus adapted to humans. It wasn’t this avian or swine virus that
came in and was accidentally more pathogenic in humans. In a lab here in Cambridge we study both seasonal flu and pandemic flu from the standpoint of – how
does the virus evolve? And how can we predict that evolution and make vaccines
to try to artificially evolve the virus both in the laboratory and in the
computer to understand what its gonna do next and to make vaccines against those
strains that will evolve in the future. So this is the basic science of studying
evolution trying to predict that evolution.
Something that’s nobody has ever been able to do for a complex organism. And
then working to use that understanding to make better vaccines. On the pandemic flu side we do a similar thing where we look to see how that virus is changing –
that virus how it changes in birds and how it changes in birds and in
other species and to try to see what possible variants out there might be but
there might be and again to make vaccines that could protect against all
of those variants that we see. Flu is very difficult to eradicate because it’s constantly mutating and changing its genetic information. We work on the
influenza virus and in particular on the enzyme that copies the genetic
information of the virus when this enters our cells. Specifically we’re
interested in how this enzyme can do this activity and how it inserts
mutations in a viral genome that leads to the formation of the new strains to
which we need to develop new vaccines. And we are also interested in when this
enzyme messes up how it triggers the innate immune resistant and helps cause
disease. We really don’t know why we haven’t seen a pandemic as deadly the 1918 pandemic. Scientists and public health officials are extremely
concerned the national risk register which is the way that our government
plans what are all the risks to civil society in the UK. There’s only two
events that are up there in terms of the most catastrophic and that’s a terrorist
event or a influenza pandemic. There is a real threat that there can be such
pandemics for example the H5 in the H7 flu viruses that have infected now close
to 2,000 people and killed about half of them. There has been with the H7 viruses
some transmission from human to human not very efficient and it hasn’t really
taken off. If either of those viruses did adapt to really transmit well between
humans, there’s a real concern that it could be as bad as the 1918 virus and
this is why there is so much research done for the public good to try to
understand what’s happening and so much work done by people in public health and
preparing in hospitals in case something like that happens. Well experts like to
say it’s not if- but when? Coming at it as a mathematician it’s happened a lot of
times in the past, it’ll probably happen again. The 1918 pandemic is difficult
because of lack of data but the most recent influenza pandemic we had was in
2009 and from that pandemic there is some very good data. If we understand how
the 2009 pandemic spread maybe that tells us something we can use to help
control future pandemics. We can’t stop them, the alternative is at least to
allocate our resources better to try and reduce the number of cases in each place. Looking back a hundred years to the last pandemic also invites the question of – a
hundred years from now what will we be like in terms of how well we are
protected against flu? Or what things we could do to protect ourselves in some
situations? Surely we’ll be in a situation where we know
more about what viruses are in the world and where they are, surveillance will be
so much better. Surely we’ll be in a better situation
where we have better drugs and better vaccines because we know more about the
virus so we know more about its weaknesses, we know more about our immune
systems and we know how to enable them to fight those pathogens better. At some point we will have a universal vaccine that will protect us against flu for the
rest of our lives. When this is is a whole other question. There are a great
number of approaches and really good ideas to doing this.There are already
attempts at this that are at a quite advanced stage. It might be ten years
from now, it might be twenty or thirty or forty years from now we really don’t
know.

21 Comments

Add a Comment

Your email address will not be published. Required fields are marked *