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  • This'll evening, I thought I would talk for about epidemics, and the reason I've chosen this is a topic and chosen infectious diseases as my first year off lectures is because they were in this this year we're coming into, which is the 5/100 year off the birth.

  • It's Atomics question, by far the dominant part off medicine.

  • So when this college was founded, medicine was very largely infectious diseases, and they're broadly divided into endemic diseases, diseases that is there all the time, in the background of which there were very many during Thomas questions lifetime over the top of which occur epidemics where you suddenly get a surge off a particular infection.

  • And during his lifetime, there were many epidemics that we know about almost certainly many epidemics we do not know about.

  • So the worst example to moderately sized plague epidemics here in London, a syphilis epidemic that really occurred throughout his entire lifetime on in many ways come to an end till the beginning of this century of the last century.

  • Rather, a smallpox epidemic on the background of ongoing smallpox typhus epidemics on a disease that was considered pretty unique to the UK, UK the English switch sweating sickness, which of which there were two major outbreaks in his lifetime.

  • So there were very many epidemics at that stage.

  • Now play of which is to say he had two epidemics in his lifetime is an example off the extraordinary power infectious diseases have historically had to shape human history, but also the human capacity to respond to those diseases.

  • Exact estimates are obviously difficult on dhe views, very, but I think most people who've looked at this consider that play reduced the world's population during one that some of its bigger pandemics from the estate mated.

  • 450 million to around 350 million, Uh, maybe slightly more than that in the 14th century and astonishing drop in global mortality on Europe, which was very badly affected.

  • Between 30 and 60% of the European population died.

  • The impact of that on society clearly cannot be exaggerated.

  • The risk of a plague epidemic or pandemic now significant one is now zero, although epidemics will come back to occur to this day.

  • This is a, however, also the Centenary year on the Centenary month off the last really serious global pandemic on that was the 1918 20 h one n one influenza pandemic, also known as the Spanish flu.

  • This probably killed between 50 and 100 million people.

  • And to put that in some kind of perspective, I've just showed the death toll in the United States, where the data reasonably reliable, comparing the number of people who died in that flu pandemic in the U.

  • S.

  • A.

  • With all the people who died in every war in the last century in the US, more people died in that single pandemic than everybody in the U.

  • S.

  • Who died in every war first World War, Second World War, Vietnam and career.

  • That puts in perspective quite how serious this was.

  • And as I say, there are people living today who lived through that pandemic.

  • These kinds off and athletics and pandemics can come on extraordinarily suddenly on spread very rapidly.

  • So let's take that 1918 pandemic and I'm taking the USA because we combine good data on large geography.

  • Looking at this map we have here on the screen, what you can seem dark colors are the area where this end of the United States on spread before September, the 14th off that year.

  • This is exactly 100 years ago the areas in the light colors, most of which are relatively remote but where it's had got to after October the fifth, so that spread across the USA occurred in a period when there was very much limited transport just after the war, over the period of less than a month.

  • And if you look at the spit spiking mortality we saw in that year, comparing the October of that year to the October off the years previously and this these were the years of privation, this is during the war, you can see the massive impact that had immortality just in this month of October, exactly 100 years ago.

  • So when really serious pandemics happen, they slam into society with extraordinary force and speed, and they were doing this even in pre industrial times.

  • So you think about play or the epidemic of syphilis, which was really developing during Thomas's lifetime, that this is, for example, a map of plagues spread on.

  • What you can see is that it spread really quite rapidly across Europe in the medieval period, when transport was considerably slower than it is now they're not a slightly think people make.

  • Imagine on, for example, syphilis, which was as far as we can tell.

  • A new disease to Europe around 14 94 spread after battle the Naples all around the continent, probably within a matter of months.

  • And it is certainly recorded as far north as leaf, for example, by 14 97.

  • So these diseases could spread even in periods when transport was much slimmer.

  • So it's therefore possible but wrong.

  • But many newspapers make this point wrongly s.

  • I'm gonna make it for them and then say it's wrong that we're increasingly vulnerable to epidemics because off the massive transport networks we have by land, sea and air.

  • This is just a map off the transport links in the world.

  • How many places you can get to within 24 hours on, as you can see, the United Kingdom?

  • Is that right in the center of this?

  • However, the reason that this is not actually a worrying as it looks, is that being rich as a society massively hardens society against epidemics off any sort.

  • And it does this not primarily for reasons of medicine which will come onto the Mets and does play a role.

  • But in fact, because of all the other things that lead to a successful rich society agriculture, for example, leading to substantially better nutrition engineering, leading to better housing, sanitation, clean and plentiful water and clean a heating as examples.

  • So there are many things we do societies which are not designed to prevent epidemics, but do so just as the process as countries become wealthier and more developed.

  • But that doesn't mean that epidemics have gone away far from it.

  • I put up here just six, and there are very many others.

  • I could have chosen just six off the epidemics that have occurred in this year 2080 in the top pro.

  • I've shown three, which would have been very well known to citizens of London at the time.

  • The foundation, this college.

  • There's a significant outbreak off multi drug resistant typhoid in Pakistan of cholera in Zimbabwe and Yemen, or come back to Yemen, kind of play in Madagascar and we're just about to enter plague season now.

  • So I'm anticipating a second plague epidemic that they're quite frequently and on the bottom row, some diseases that were not known in the time off so gruesome protective Thomas in London but are quite wide spreading a dis point in time.

  • A monkey pox outbreak in Nigeria.

  • Had this happened in London at that stage, people would have assumed this is smallpox.

  • They look almost identical.

  • Have actually bean now three cases this year in the UK, which is spillovers from that theme, er's Middle Eastern Corona virus outbreak.

  • That's occurring particularly in Saudi Arabia.

  • A real worry to people because of people becoming very crowded during the hajj and other pilgrimages and then scattering hat to the four corners of the world, often to places with relatively limited health service's on dhe at two a bola outbreaks that have occurred in in DRC this year, one of which is still ongoing and there are many others.

  • So the point I'm making on this is that epidemics occur every year in every continent and they kill people.

  • That's a societal impact will depend on many factors.

  • They will depend on how many people and who is affected, and it may be certain societal groups who are more important for society's functioning.

  • They're not more important to their families.

  • For example, the great flu pandemic of 100 years ago, particularly who was mortality in people of young working age.

  • So the impact on society was very considerable.

  • All flew 10 secure, the very young and the very old.

  • This also picked out people of young working age on many pandemics, and I'll come on to an example of this later tend to pick out people.

  • Your health care workers making the response are considerably more difficult, and I've given example from Nigeria.

  • This is just an outbreak.

  • The index case is not a health worker at all.

  • The next cases in blue are all health care workers, doctors or nurses, and all the ones boarded in red went on to die.

  • So being a health care worker in an epidemic or pandemic can be a hazardous occupation.

  • Epidemics cause substantial panic.

  • Andi have a substantial social and economic impacts, very often way out of proportion to their actual medical importance.

  • So let's take several off the recent epidemics and you'll recognize many off the front pages of the newspapers involved.

  • He's tended to dominate the news for very long periods, including in countries which had almost zero chance off significant onward transmission leading the U.

  • K Let's take saws between November 2002.

  • In July 2003 the SARS outbreak, which dominated the news for quite a long period of time, caused just under 10,000 cases on just under 1000 deaths in 37 countries.

  • Now that is obviously a substantial tragedy for the individual families, but this is a small effort out outbreak.

  • This outbreak, which we happen to know the data because the World Bank have looked at it, probably wiped around $40 billion off the world economy because it closed on airlines on led to panic in the particularly in Southeast Asia and Canada.

  • A massive influenza pandemic would be a lot bigger than that by many factors and will undoubtedly have a really serious societal impact.

  • So these can have a very big impact on society even if they are medically relatively less important.

  • The first question I'm invariably asked by ministers is Why can we not predict epidemics and prevent them before they start?

  • And the answer to that is they come from almost every direction.

  • Predicting and trying to prevent epidemics before they begin is extremely difficult and lots of people have tried and lots of people have failed.

  • And this is really because the great majority of new epidemics come.

  • Richard, News of the world come when a disease which is in an animal species, jumps over to humans.

  • And I've just taken a few animals here.

  • Thes friendly fruit bats are a source of Ebola.

  • This gentleman here or one of his relatives source of HIV, uh, nose the inside and in the Middle East theme Mexican pig flu, which many of you remember on B sc.

  • So in the great majority of new pandemics that a new to the world animals is where they come from.

  • But nevertheless being humans, we tend to blame foreigners on dhe, sometimes rather predictably so.

  • For example, when syphilis came to the UK, we called it the French pox, the Neopolitan pox on the Spanish box, depending who we dislike.

  • Most of that stage people talked about English sweating sickness on DSO on and Spanish flu and so so blaming foreigners is what we tend to do.

  • Actually, animals is where they tend to start.

  • But although the first reaction is almost injury, panic epidemics actually can be addressed systematically and The rest of this talk is about how systematically you can go through a new epidemic and say, Now, what are we gonna do?

  • And how we gonna respond?

  • Depends really on five things.

  • The first is mortality or severity off the disease.

  • A trivial infection is probably not something which is going to require such a major response.

  • The second question is easier treatment available and if not, can we find one very quickly?

  • Third question is, is there a vaccine available and then two very important things which are more actually illogical.

  • But actually the key thio any epidemic where the answer to the last things that treatment or vaccine available already is critical.

  • The force of transmission, which is a mathematical concept.

  • But I'm glad to say an incredibly simple one.

  • And the route above a ll the route of transmission.

  • The route of transmission is the key to controlling an epidemic.

  • Just before I go into the main technical bit off the talk, I just want to make three definitional things.

  • An endemic disease is the background rate of an infectious disease in the making these definitions cause I will use these terms repeatedly, and I want to be clear what they mean.

  • It maybe zero.

  • So an epidemic, maybe monkeypox.

  • A relatively small number of cases.

  • But the normal number is zero.

  • Or it may be a quite a high number, which, actually, then you have a peek off if you think about.

  • For example, pneumonia.

  • Pneumonia is an endemic disease in the UK It kills very many people in the UK probably 29,000 people a year on average.

  • But we don't consider that an epidemic.

  • It's just there the whole time.

  • Whereas we get much more excited about epidemics which killed much smaller numbers.

  • So endemic diseases can be quite serious, and I'll be talking for most of the rest of this series on endemic diseases.

  • And then you have outbreaks or epidemics, and that's when you have a spike off diseases above the seasonal background.

  • You may be a small spike for seasonal background is almost zero where it may be a large spike, and the terms are slightly slippery.

  • But in general, people mean an epidemic to mean quite a large outbreak and an outbreak to mean a geographically localized one.

  • So I'm going to use those terms that way, there's you could get a bit panicky about our use him and finally a pandemic.

  • He's an epidemic which occurs worldwide, or at least cross is a lot of international boundaries on Officially, it's declared by the World Health Organization.

  • So the first of the things I said is we're important is mortality and mortality varies very substantially by different epidemics.

  • But of course it has to be to have an impact.

  • It has immortality multiplied by the number of people who actually have it.

  • So let's start off with a bola recent about epidemic, the mortality for a Buddha epidemic with somewhere between 60 and 70% if you've got the disease.

  • That was the probability of dying smallpox, the major former smallpox.

  • Around 30% of people would expect normally to die.

  • You think about the H one n 1 1918 flu pandemic, but that only had a mortality rate of about 3%.

  • But because it affected many millions of people, its impact on society was actually considerably greater on.

  • Finally, I put down a disease which really started here in the UK new variant CJD, which came from BSC that had 100% still has 100% mortality.

  • Um, but of course, relatively small numbers, So the mortality rate is very important.

  • But that may not just be a function of the disease, So you've also got the mortality may very bone nutritional status by ethnicity by age or a variety of other factors.

  • So if you just take measles, a disease which, wrongly lots of people think they're quite, is quite a trivial disease in epidemics of measles across Africa, for example, when they occur, you're typically yet a mortality rate of somewhere between five and 10% of all Children.

  • To get measles will go on to divert.

  • It is not a trivial disease.

  • Handy up thio one in 10 in measles, on the other hand, in an endemic in the UK because people are well nourished, the mortality rate for measles is around one in 5000.

  • Still not trivial but very substantially different, say mortality can vary even within the same disease.

  • This is most clear if you look about influence a looker influenza and hear.

  • What I've done is a table two by two table comparing for while three influenza outbreaks and the key things you need to understand is that transmission and mortality in influenza are to a large extent not related to another.

  • So you have some epidemics like the Spanish flu pandemic, a fairly high mortality, 3% but not massive but massive impact because it had very high transmission.

  • Then you have the recent H seven n nine avian influenza that has relatively small numbers.

  • It's not very transmissible.

  • You pretty will have to do master beak resuscitation to catch this from a bird.

  • But if you catch it, your chance of dying is 30%.

  • So flu can kill a lot more than 3% of those who get it.

  • Or then you have the 2009 swine flu pandemic, and that had a 0.3% mortality so tense of that of the great flu pandemic of 1918.

  • But it had very large numbers, so these two are largely unrelated, and I think the point I'd like to make with this is the Spanish flu pandemic is not the most dangerous that a flu pandemic could.

  • Yet he could actually get worse.

  • So think about that when you're feeling cheerful, even if controlling an epidemic is not possible.

  • Stopping people dying, however, should be, and you can, usually in most pandemics.

  • Seven.

  • That's substantially reduce the chance people dying once he worked out what the cause is that maybe some specific things you can do so if it's a bacterial epidemic, for example, you can use antibiotics on most new bacterial infections.

  • New, particularly from animals, will be antibiotic sensitive.

  • Not all You can use anti virals if their viruses but viruses anti virals are too much earlier stage of development.

  • So most viruses do not have an antiviral that works in the movies that we know works for them.

  • It's a parasite.

  • You can use anti parasitic CE and so on.

  • And then the recent treatments you can do, which are disease specific but which are not actually designed to kill the infection with antibiotics, anti virals and a good example of this is vitamin A, which in measles will massively reduce the mortality, particularly malnourished Children.

  • This is not an antiviral drug, but it is a drug which has a very big impact on reducing disease, and then you can have some secondary things like antibiotics and severe influenza.

  • It doesn't stop the influenza, but it stops people then developing pneumonia so you could work out ways to counter people dying, even if they catch the infection.

  • And, of course, there's always standard medical treatment with fluids on ventilation after the question, Why we not predicted this, and why could we not stop it before it began?

  • The next question.

  • Policymakers will reason, we ask us and have asked, I suspect, ever since Jenna produced cowpox vaccine to prevent smallpox is when can we get a vaccine on?

  • The short answer is if the epidemic is with the disease, where we already have an effective vaccine very quickly provided their stocks of it.

  • So let's take the examples yellow fever, measles, polio, smallpox, thes oral diseases where the vaccine we have is highly effective.

  • If we were to have an epidemic of any of these, we should be able to stop it.

  • Occasions when we can't on bean some recent small pops I Yeah, so recent recent yellow fever outbreaks.

  • Don't the newspapers get hold of that smallpox idea?

  • Yellow fever epidemics on they have occurred in part because of the world has got a global shortage of yellow fever vaccine.

  • It's not that we don't have to make it.

  • It's simply we've got a manufacturing problem.

  • Then you can have some diseases where there's a very into the known disease with a known vaccine on the classic.

  • For this is influenza, which, as you all know every year, has to be reformulated.

  • To meet the current form, you get a pandemic.

  • You won't know what the current form is, and you'll usually take at least four months.

  • Between the time that the pandemic has started and the point you can get an effective vaccine.

  • That's the minimum lead time.

  • It might well take longer or new diseases, even if it is possible to get a vaccine vaccine will usually take years.

  • So it is not realistic to think that in the first phase of an epidemic, you're gonna be able to control it with a vaccine because that is simply not biologically or or clinically feasible.

  • And for many diseases, we've tried really hard for decades to get vaccines and so far have failed to get ones that are more than partially effective.

  • Good examples being HIV and malaria.

  • So vaccines have a major role, but the idea that they're going to be the solution to every epidemic is optimistic.

  • If you do haven't backed vaccine, However, there are a variety of ways you can use it.

  • The one that everyone would think off is vaccinating the whole population.

  • Andi, this is going to work.

  • If you got a highly effective vaccine that has low side effects is easy, ideally is cheap, and this will provide some degree of immunity for the whole population.

  • Even those were not vaccinated will be protected by the fact that people around them are vaccinated.

  • Was so called herd immunity.

  • But there may be other groups are the situations where you don't have that kind of vaccine.

  • We don't have it in large enough lance on.

  • In that case, you can have two other approaches even take.

  • You could vaccinate high risk groups, so people you think are particularly likely to get an infection and then pass it on.

  • That might be, for example, health care workers.

  • It might be, for example, sex commercial sex workers if he was a smash, it sexually transmitted infection and the third approach you can take, which is probably the least intuitive but actually is extremely effective in the right environment, is what's called ring vaccination.

  • This is where you find the case.

  • You then vaccinate everybody who's come into contact with that person.

  • And generally everybody has come into contact with those people as well.

  • This was tried effectively with smallpox eradication attempt on.

  • We're using it again now, in the most recent voter outbreak.

  • So that but that does depend on the vaccine.

  • You have being extremely quick acting.

  • If you have a vaccine that's gonna take three months to have its effect, this approach is clearly unlikely to be effective.

  • The final concept is the idea off force of transmission.

  • And this is the one bit of maths.

  • I'm gonna d'oh in this talk.

  • But it is a simple one.

  • The key thing to understand with force of transmission this is the central understanding of epidemics is if you have a disease which on average passes itself from one person to one person to one person on average, that disease is stable in the population that has a force of transmission on our off one.

  • If one person gives it to two people, give it to four people, give it to eight people and so on that has an are of two on that disease is expanding exponentially.

  • And for those of you who work in the city, this is a compounding problem.

  • Expects financial increase over time.

  • That is what causes epidemics and, if they are, is below one.

  • Let's say it's 0.5 10 people give it to five people.

  • Give it to 2.5 people on that disease is on its way out.

  • The key within A to control an epidemic is to try and work out what is our is and get it below one.

  • Once it's below one, the epidemic is gonna die and say that understanding this number is Central Thio and in fact, very large numbers off infectious epidemics have really quite low ours.

  • They're quite close to one, so the idea of getting them below one is entirely biologically feasible.

  • So if the bowler epidemic, for example, are with somewhere between 1.2 and 2.5, flu pandemic probably between two and three, polio bit higher for port for 5 to 7 HIV tune so on.

  • There are, of course, some diseases where they are is really high.

  • On in particular, I point out malaria in Africa, where the are for the disease can be over 100 getting that below one.

  • He's going to be problematic.

  • And alongside this not exactly the same thing is the idea of the doubling time.

  • How long does it take for each number of cases to double?

  • And that's a combination the are and how frequent wth E case cases pass things on.

  • But for the rest of this talk, I'm gonna talk about route of transmission because this is the key to control and they're basically five.

  • And what you can do to control an epidemic depends on which route of transmission you've got.

  • You have airborne roots with influence, and examples of those are influenza murders and SARS food and water borne roots.

  • Cholera, typhoid, BSC.

  • It's agent CJD, a touch of Ebola or Lhasa vector borne.

  • That means insects, Zika, Deng and play would be examples or sexual, for example, HIV or syphilis.

  • Now, for all of these, you could usually have a predominant route, and you may have a secondary route.

  • But generally one route dominates, and if you can control that route, the disease can be brought under control.

  • Let's take some examples.

  • Ebola is a touch disease from, and most people know this.

  • So I'm just going to use is an illustration despite the fact that actually, if you have a bola even if you're a relatively close to someone but do not touch them, you're not gonna catch it.

  • So, for example, if the promised had Ebola, I would not consider myself a risk standing this far away from him.

  • Uh, Ebola managed to spread really quite effectively through West Africa.

  • And the modeling for that demonstrated that we were soon going to have a disease that was well out of control, even though this was relatively difficult to pass on by touch.

  • So the situation at the start off the epidemic disease with high mortality, very few medical countermeasures, no vaccine, although there was animal data showing that vaccines might work, and our of between 1.5 and 2.5, we worked that out fairly quickly on a doubling time of about two weeks.

  • On the main route of transmission was touch importantly, people were only infectious when they had symptoms, but they remained infectious after death.

  • Those are really critical points.

  • And what that meant therefore, was because this is a touch disease.

  • We had to have touch interventions and we chose four areas where touch was passing it on in hospitals.

  • And it was about control of infections in hospitals around burials because people infectious after death and they were touched after death.

  • So it was about safe burials.

  • Safe burials was easy.

  • A safe burial was acceptable to the family, much more difficult.

  • So that was a key thing.

  • Reducing transmission that community by basically finding people with symptoms and isolating them on.

  • Then generalized isolate a social distancing, for example, encouraging people not to shake hands when they met quite simple things that would make it less likely they were touched someone he was then infectious.

  • And what you found with Sierra Leone is if you put these together, you you're in a situation where the are began to fall really quite fast.

  • So the major intervention started in August and September.

  • You had are off over 1.5 and the are then began steadily to drop.

  • Now, of course, as long as it was above one, the number of cases continue to rise that one of the things that happened in this epidemic is that people in about October, said, This isn't working because the number of cases was going up, but actually looked at the are.

  • What you could say is that was coming down and we could see there was gonna cross one in round about this December on.

  • At that point you reach the peak of the epidemic and it passes on.

  • So you have used our to see that your interventions were going to be effective, as I said previously, a very heavy burden on health care workers.

  • And that did mean that in our early interventions we were between a bit of a rock and a hard place.

  • Healthcare workers were absolutely essential, but they were also the most vulnerable of people.

  • It was a big advantage.

  • Epidemiologically, too early intervention.

  • But if you put untrained people who didn't know how to use personal protective equipment into our hospitals, you had a situation where around 8 to 10% off the health care workers who were initially treating cases quarter Bhola and around 80% of them died.

  • And so you had this real trade off between getting in early and controlling the epidemic and throwing people essentially over the top into a very dangerous situation and that tension had to be resolved.

  • We've now got a second outbreak this year off the Bola and interestingly, the way we're having to address it is quite different.

  • The most positive difference is that we've now got a vaccine.

  • I'm announcing ring vaccination which was not available previously on the cause of the work that was done in the first epidemic.

  • We were able to go on to the 2nd 1 but we also have found that the social interventions we used have become much more difficult.

  • A bowler in this area is politicized.

  • It's a very politically difficult environment.

  • It's a very unstable group area for many armed groups, substantial distrust of the government on I think it would be far too early to say we've got this outbreak at the moment under control.

  • Second major pandemic to consider is HIV pandemic This is a sexual disease.

  • I'm going to get taken example of each of the roots, mate.

  • You're the other after the flu pandemic off 1918 the other really major pandemic off the last 100 years, around 35 million deaths to date.

  • This is a really serious disease and again if you look at the spread in Africa that happened from 1984 through 2 1999 I was working in this part of Africa in 1999 and watching 1/3 of people my age dying of HIV was quite a depressing experience, including many of my friends and colleagues, you know, quite a rapid spread through the continent.

  • So the start of this epidemic, which was recognized in writing if you want to be going on early on that, we realize it was a very high mortality.

  • Uh, we had no medical countermeasures.

  • Very few.

  • We had no vaccine.

  • The R was roughly 2 to 5, but very variable main route of transmission was sexual.

  • That was worked out quite early on.

  • But there was an important secondary route that was intravenous people sharing needles, basically sometimes people who would be a recreational drugs but also healthcare workers using the same needles for lots of people.

  • So this is not just drug use.

  • Intravenous drug users on dhe importantly, people were infectious when they had no symptoms.

  • There was no way of telling that someone had symptoms on.

  • They would be infectious for very many years completely different from the Ebola situation.

  • So in the absence of a vaccine, a drug or anything else, the one thing we had was behavior change.

  • And there are lots of approaches to try and change sexual behavior.

  • I have to say a great number of them were highly ineffective, including ones which you just look at them and just think one earth you trying to do here.

  • So changing behavior is difficult, but for a sexually transmitted infection was clearly absolutely essential.

  • And one thing that we were successful in doing is getting people to know their HIV status.

  • But that took really quite a long time on by the alternative route.

  • We have to consider those of intravenous drug route.

  • It was also about behavior change, but it was not really about trying to stop people who were addicted to one of the most highly addictive drugs ever known, uh, heroin to not be addicted.

  • That was simply not realistic.

  • So it had to be to say, don't share needles.

  • And that was quite a difficult political battle to fight because a lot of people wanted to just carry on saying, Well, you know what to expect Just stop using this drug.

  • They obviously haven't ever bean addicted to heroin.

  • So the approach we had to then move on to, apart from behavior change, was drugs to treat people and that really has bean waters turned.

  • The tide with HIV has not bean a preventative approach, although that has been important.

  • But it is being drugs to stop people dying.

  • The first anti retrovirals were in 1986 and they failed fast within weeks of taking them really extended to life for no practical purposes for very long.

  • Got into the proper anti retroviral era in about 1996.

  • But they were very expensive and clearly not affordable in the part of the world where great majority off the infection waas.

  • The drugs are now widespread but still under 50% of people who have HIV on them.

  • But there's now a very good outlook for people who know they got HIV and are ineffective drugs with HIV.

  • We haven't managed to stem the epidemic although it is going backwards.

  • But we have managed to do is move from a situation that everyone died to a situation where almost everyone who's on drugs, lives a good and fulfilled life.

  • We have looked at vaccines and drugs to prevent HIV.

  • That's been a huge investment in HIV vaccines over many decades, and we have yet to get a vaccine that is anywhere near being deployed in the general population.

  • It demonstrates that sometimes the vaccines are relatively straightforward, biologically that sometimes they really are not.

  • What may have an effect on the epidemic, however, is that people who are on treatment are much less infectious and therefore the widespread use of treatment if you treat people early may well lead to a reduction in the epidemiology is a debate about how long people need to be on treatment for this to be true, but it clearly is going to have an effect, and you can now use drugs as prophylaxis in high risk encounters.

  • So what we got the HIV is incidents in terms of number of new cases is drifting down, but quite slowly there will still be a lot of HIV new cases at the point when I retire and probably at the point when I die.

  • But the number of people who die from HIV massively reduced, so we've dealt with this this epidemic by treatment and a high income cases.

  • New cases are beginning to drop on dhe, but we must be aware that eight more about 1.8 million people became newly infected with HIV just last year.

  • So this is not a disease that has gone away by any means manner of means.

  • And we're not like to get rid of this unless we do get security of drug, which we do not only have or a vaccine or both.

  • And both of those I think of some way off.

  • There are, interestingly, some parallels with syphilis in the UK Um, syphilis entered the UK around the time just before the time after Thomas Grecians birth.

  • Um, almost exactly this time.

  • 100 years ago, there was a royal commission that asked the question, How many people in London have syphilis?

  • And the answer was, 10% of men just look around you and just think about that fact.

  • What killed that epidemic was the introduction of penicillin on DSO again.

  • Treatment was what actually led to that outbreak, stopping well that that silly syphilis office, you know, third, major routes of transmission is vector borne epidemics.

  • Now rare in the U.

  • K.

  • But they remain a major global risk.

  • They used, of course, to be extremely common in the UK, so vector borne epidemics.

  • That's a stage.

  • When this college was founded, epidemic typhus passed on by fleas, play also passed on by fleas and malaria, particularly in the less salubrious bits of Essex passed on by mosquitoes.

  • Actually, the UK now has very few vectors with epidemic potential, although they can pass on some diseases and the important ones are ticks on dhe.

  • Potentially images are there.

  • There are no ignitable on diseases at this point in humans globally, vector borne epidemics are extremely common mosquitoes of the main culprit.

  • But sand flies, fleas, biting flies, ticks and mites are all capable of passing on different infections.

  • So there's a lot of actors out there on the question is, Where do they live?

  • Um, Professor, Thank Frank Cox, who was a previous aggression professor of physics, is the real expert on the eighties mosquito, and I've stood on a couple of slides from him just to make a point.

  • AIDS mosquitoes are one example of a mosquito which can pass on many diseases so can pass on yellow fever impulse on Deng and pass on decorating Gagne, for example, on Dhe.

  • It has spread quite widely because it is very well adapted to living in peri urban settings.

  • So this, for example, shows the map off the transit lead the spread off Denki through the Americas over three decades because this mosquito is ideally suited to the environment.

  • On a recent example was Zika, which again hit the front page, is a disease that have been around in Africa since at least 1947.

  • That was when it was first described, probably obviously a lot longer than that managed to hitchhike its way across the Pacific to Latin America and set up a very major epidemic in Brazil, which I again many of you will remember.

  • This is the one that was found to cause very small heads in some newly born babies, almost certainly leading to a very substantial neurological damage may well be many other babies who are damaged, who we do not yet know.

  • What you found was again very small.

  • Number of people have babies with very small head's born and then in 2015 a huge spike off these cases and extremely good epidemiology by Brazilian scientists quickly worked out.

  • There was a link to Zika, which was incense in no way obvious, um, on dhe.

  • We therefore had a significant epidemic with high transmission in Brazil, around 12% of pregnancies in the first trimester in people who are infected would go on to have microcephaly, and probably more of them have neurological, deceptive diseases.

  • It is a significant infection, no drugs, no vaccines.

  • And although we know the mosquito, we don't have very good ways of controlling.

  • It is a lot harder to control than some other mosquito species, although control measures are available and improving, and there's a possibility of a sexual route of transmission as well.

  • What we then had was the peak of the epidemic.

  • And then it began to decline, and it began to decline for really two reasons.

  • One of which was that the climate, the way the rainy season changed, making it less easy to transmit the fewer mosquitoes practical purposes on the second was that a much larger proportion of the population became infected and then became immune to the infection Is some combination of those two.

  • This was fortunate for many people in Brazil was also actually fortunate for the Rio Rio Olympics, which otherwise could have bean significantly impacted by this disease.

  • But the question after this outbreak in Brazil was, Where else could it go?

  • And the answer is, in theory, anywhere where the main mosquito that passes it on eighties aegypti mosquito is found, and this is a map of where it is found, and then it has a a close relation, something called a tease out the pictures.

  • It's not clear how good this mosquito is that transmitting Zika is still not really clear.

  • A good this mosquito is.

  • But this one has an even wider distribution in areas which are a bit colder because it's able to overwinter under certain circumstances.

  • What that means is that this particular exits, the eighties aegypti, is not well seated to Europe, Europe but this particular vector eighties.

  • All the pictures is gradually spreading through you, and these are maps off where eighties are the pictures.

  • That could potentially be because this climatic suitability for it in the next few years.

  • So there are part large parts of Europe, including small parts of England, in fact, which are capable in theory, off maintaining populations of these vectors and therefore potentially of maintaining transmission often epidemic.

  • So we've had a touch sexual and vector borne.

  • I'm now gonna move on to water borne water and food again.

  • He relatively quick on this one because this is a disease which should not exist.

  • Cholera.

  • And there's a massive cholera outbreak in Yemen at the moment and has been, for the last year 1.2 million suspected cholera cases and over 2500 associated deaths, with 29% of them in Children under the age of five.

  • Look at that and weep because this is a manmade epidemic.

  • Currently there are about 100,000 cases a week of cholera in Yemen.

  • Now we know entirely what to do about cholera was one of the first properly epidemiologically investigated diseases and it was actually its route of transmission was demonstrated really clearly first here in London by this gentleman, Jon Snow on dhe.

  • He did two things, one of which was some epidemiology that no one really knows about where he mapped different water companies in their rates of cholera.

  • But the 2nd 1 was, people do tend to know about is he mapped outbreaks around the different pumps in central London and demonstrated that they were mainly centered on one pump in Golden Square on Broad Street and rather theatrically.

  • He went removed.

  • The pant pump handle, uh, from that pump to ensure that no one could actually use it.

  • And as a result of treating the water and stopping the use of the pump, the color outbreak stopped.

  • So we have known what to do about this since 18 54.

  • Unfortunately, the reality is that epidemics have always and will always follow war, civil unrest and disaster.

  • What development people would call development in reverse.

  • And there are many reasons for this.

  • Water, sanitation, housing and vaccine programs get destroyed and therefore all the things that have bean we built up.

  • His defenses are removed, and therefore all foes like typhoid, typhus and cholera re emerge.

  • They they do that as an absolute as night follows day after wards, you also get rapid movements off populations exposed, exposing people who are immune to disease.

  • So I'm not immune to a disease to an area of risk.

  • You get people moving into marginal lands because they've been displaced where there's lots of vectors which can pass things on and get breakdowns of social norms.

  • So you get increases in sexually transmitted infections.

  • Basically, war is an absolutely perfect way to drive an epidemic off any thought.

  • Not all food and water borne epidemics are caused by war.

  • They can occur even the most in the most peaceful and prosperous societies, but usually only under quite limited circumstances.

  • A recent example least one that is able to many people in the audience will remember was the BSC new variant CJD epidemic that started here in the UK and the reason this was able thio get around our very stringent public health things that protect without most people knowing about it.

  • You're protected by a Web off rules regulations, inspections on dhe, other paraphernalia which prevent foodborne and water boom infections occurring.

  • This is an example where the usual barriers didn't work.

  • He wasn't destroyed by cooking and we therefore had to remove it from the food chain.

  • And that leads to a situation that over 180,000 cases of BSC and cattle this'll end in due course.

  • So far, 278 cases of new variant CJD, but numbers are gradually taking up.

  • Um, there was a massive coal of cattle removal of awful the neurological tests.

  • You changed the feed so we were able to respond to this.

  • But nevertheless, it does demonstrate that even in highly developed societies, you can still get our diseases with by the food borne or waterborne right.

  • But I'll finish in terms of the diseases I'll go through before I round up some points with pandemic influenza.

  • Because this remains are by far by very, very long distance, our biggest known epidemic risk.

  • It is the top off the UK national government held risk register, outweighing every other risk that the nation, uh, faces.

  • And for very good reasons, airborne risk is indiscriminate.

  • It's much more difficult to interrupt another transmission routes.

  • You know, it's stopping people touching around.

  • Other changing sexual behavior may be difficult.

  • It's a lot harder to stop them.

  • Actually breathing in the environment around people spread of an influence.

  • A pandemic is really rapid, as I demonstrated in need some of my earliest slides, the massive speed at which the 1918 pandemic occurred exactly 100 years ago, and a very high proportion of the population would be affected at once.

  • So if you think about a situation where around 20% of the population were actually infected, that most of those who are not infected would probably be caring for Children, for grand parents, for friends who had the disease, then you take Let's say you take out 50% off all train drivers, all Super Mart work market workers, all nurses, everyone.

  • He mans the banks and just think what that's going to do to our society.

  • That is the reason why this is a really serious potential threat to the UK, and the question is not whether we will have another pandemic.

  • We will have another mandate.

  • Nick, is it really a question of when and how bad?

  • The last pandemic we had in nine and 2009 was really pretty low violence, but still very substantial numbers on just looking at that one again.

  • Just looking at the speed of this.

  • This is around the sixth of April, where it had spread to this is by the around the 20th of April by May, and by July.

  • That's the speed it occur.

  • It transmitted around the world.

  • There were somewhere between 40 and 19 million cases from this pandemic.

  • And because it was late, virulent CE, there were only only between eight and 18,000 deaths.

  • But this was this was a near miss.

  • This could have been a lot worse.

  • And there were courts wide estimates on the numbers peak of transmission of this came on incredibly fast.

  • If you look at the UK numbers, this just shows you quite how quickly this hits.

  • It's in a matter of a couple of weeks.

  • This is not something you have time properly to prepare for.

  • Officially, there were 457 deaths in two ways.

  • Almost certain the numbers were a bit higher than that.

  • We did have a vaccine available, but well after the peak, so it wouldn't have helped us.

  • If this peak of bean massive the use of drugs is highly controversial, not gonna go into controversy.

  • I could descend questions if you're interested there, Most useful have taken early but importantly, all the drugs.

  • A single mutation of the virus was enough to make it make the drug ineffective.

  • And these occurred fairly early on in the academic and a whole bunch of inevitably of interventions air cooled for like streaming it airports and banning travel, which are utterly useless.

  • It's close to other uses as makes no difference and closing schools, which does have an effect but at a significant cost to the education of the Children and to the people who are working, who then have thio stock work so they can look after Children a time.

  • So this is going to have a considerable problems.

  • We can certainly put the building blocks in place to try and address a influence of pandemic.

  • But we have to be aware that this would be chaotic and B and no plan survives contact with the enemy.

  • So the things we got in place, mathematical models were good models that will help us early in a pandemic.

  • To work out how quickly it's gonna move where it's gonna go, label virus identification that works to work out very quickly, what the virus is and where it's come from, what it looks like we've pre decided, although there's lots of debate about bits of it, which bits of the health service you'd close down first to protect the rest, cause we have to do that to work out how to do it is we worked out how to optimize vaccine production, but we all know that four months is the absolute minimum.

  • And you look at the speed of that transmission.

  • Great majority of the first wave would have done its damage will before we have a vaccine and you've got an antiviral stockpile, which is which is a lot better than nothing but has some problems associated with it.

  • So just to pull together some of the themes on this, the first reaction took her to a an epidemic.

  • Even quite a small one is usually panic.

  • And in fact, for small epidemics, panic is what causes the major problems.

  • But for big epidemic, it is genuinely big.

  • And some of the examples are given particularly 1918 3 pandemic and HIV seriously big.

  • How we respond to them needs to depend on mortality and severity, treatment what we've got, what we can adapt and what we can develop vaccines.

  • But for most new pandemics, we're not gonna have a vaccine or we're gonna have it quite late.

  • The force of transmission.

  • How close is the art of one that is really critical to what we do and then, above all, working out what the route of transmission is.

  • Because even if you don't know what the infection is, if you know how is passed on, you can then work out some logical countermeasures.

  • Once we've actually determine the route and force of transmission, we can make changes.

  • And I've put these up in one place just to stress a general point.

  • For Bhola, he was behavior change, old fashioned isolation of cases and now a vaccine.

  • But a lot later, HIV behavior change and more than a decade later, drugs cholera B J D, say, for two safe food and an absence of war.

  • An influenza vaccines, drugs and societal organization in each one of those lines, a huge amount of it is around organization of society and behavior change not around drugs, vaccines and other high end medicine.

  • So societal changing society changing normal behaviors which people normally do.

  • Shaking hands, hugging a friend, having sexual relations with your your regular partner, eating a meal, drinking.

  • These are normal behaviors.

  • You have to get people to change them in epidemics because that is likely to be the only way you're going to be able to get on top of them, and you therefore do need to know the route.

  • Although overall infectious diseases, these dotted line has significantly reduced in all high income countries as a cause of mortality compared to cardiovascular disease and cancer, epidemics remain a very significant threat even to the highest income countries and certainly in the lowest income countries, it's Thomas Grecians.

  • Lifetime infectious diseases dominated medicine.

  • Academics will always occur, but the risk is substantially smaller.

  • And I think my central point would be that wealthier countries are hardened against epidemics, not because people deliberately designed them that way that because they wish tohave sanitation, good housing, proper food, clean water.

  • If you have, those epidemics are very, very much more less likely.

  • So this would be something which I'm sure Sir Thomas question himself would have approved off as a financier, Andy diplomat.

  • Those who bring priest and prosperity do at least as much to prevent future major epidemics as doctors and scientists.

  • And since we're a lot more prosperous, I'm glad to say epidemics, much less likely.

  • But they will still continue.

This'll evening, I thought I would talk for about epidemics, and the reason I've chosen this is a topic and chosen infectious diseases as my first year off lectures is because they were in this this year we're coming into, which is the 5/100 year off the birth.

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