Hello and welcome to the how epidemics and projects based at the University of Oxford.
My name is Erica Chalmers, and in these videos, I discuss how experts research disease in a variety of ways,
as well as their investigations into how epidemics.
And today I'm here with two scientists who study human evolution and ecology in the way that they study disease.
So I have here with me Miles Christian Stenson,
who's professor of ecology and evolution at the University of Oslo and who's an evolutionary biologist and ecologist.
And I also have with me Barbara Bramante,
who's associate professor at the Department of Environmental and Prevention Sciences at the University of Ferrara in Italy,
who's a physical anthropologist.
So IRA animals, I think people might have a general idea about human evolution and how it relates to ecology and to the environment.
But can you explain a little bit more specifically how you, as an evolutionary biologist and as physical anthropologists, study disease?
So, Niels, if we're to start with you, do you work in a lab in field, work on a computer?
What kind of evidence do you use in your research? I mice, I myself mostly work on other people's data and long term time series.
So observations over many years.
And when I first got into plague work, it was analysing data from the old Soviet Union about recording occurrence of played in wildlife.
We have to remember that the plague caused by your son pestis is a wildlife disease that occasionally spills over to the human population.
And as a matter of fact, it spills over to the human population when plague in wildlife and elsewhere.
So I'm analysing these kind of data. What is the what is the structure or the dynamics in space and time?
And I do statistical models based on really population mathematical population models.
So that's what I do for a living. That's very that's very helpful.
And, Barbara, I know in some ways you also look at but from a slightly different angles.
Can you explain how your research works when you do physical anthropology?
Yes. I'm a physical anthropologist year have said that mindset that I am interested in human evolution and in
terms of population dynamics and in terms of human environmental interactions and since disease part,
especially infectious disease, that's part of this interaction between humans and the natural environment.
I am also very interested in this kind of infectious disease and in particular on plague.
And my group of us has provided the first proof that the Pasteur plagues were caused by Yersinia pestis, as well as the modern plague.
And from this point on,
we have started to study more and deep and thought that the dynamics of a senior pestis and mortalities of spreading of the bacterium in the past.
So this is really interesting, because, of course, the two of you work together and I know you work with many other researchers.
So can you explain a little bit more about how then you study flag when you're working together?
Niels, you've talked a lot about how you're part of the centre that brings together different disciplines at the University of Oslo.
Explain a little bit about your research and how it works with purpose research. What have been some of your findings?
I can. I can. I can start where we sort of got together, and I have believed that plague had reservoirs here in Europe because we have,
you know, superficially, the right condition.
However, we did a paper not with Barbara, but with other colleagues here that was published in 2000 and 14 or 15.
I believe where we demonstrated that the occurrence of plague in harbour cities in
Europe was linked to good plague conditions in Central Asia several years earlier.
So then I became convinced that as a matter of fact, plague must have come into Europe several times.
And then Barbara was the obvious partner for linking up here because she was
studying the genetics of old skeletons or actually the teeth of the skeleton,
and you can expand as much better on myself. Yeah, and that's the work that Barbara did.
And Barbara, we did together really support our original idea that plague must have come in several times to Europe.
So that's really where we met.
We had to be understood pretty much how plague ends in wildlife, but we don't know how the dynamics in the human population is.
Her project was really spot on to answer that question.
I think this is a really interesting point, and Barbara, I want you to expand a bit on this,
but especially thinking about what kind of sources and data you're looking at,
because many of us might know that, for example, historians of plague, we've talked to some of them in this project look at textual sources.
So the records that humans are writing and leaving behind, but you seem to be looking at different types of sources to study alongside.
So, Barbara, what kind of sources than are you looking at?
What are you combining? What kind of data are you using when you're studying plague and trying to understand the course of an epidemic?
Yes, it's a molecular anthropologist, I work in the lab and I have a group working in the lab and we try to isolate DNA,
ancient DNA from the teeth and to reconstruct the genomes of the ancient bacteria and to compare them.
And by doing so, we can reconstruct also the phylogenetic three of the bacteria, and we can better understand the dynamics.
But the phylogenetic tree is not so easy to be interpreted, and we need also other kinds of data.
And this is also the reason because of these interactions, very fruitful interaction with ecologists and archaeologists.
We need a lot of competences, of course. Also, the storm comes because we have always the eastern evidence,
historical evidence in the background of when we try to interpret data, find a genetic tree.
So unless you've already mentioned something about plague ending the plague ending only in certain groups or certain,
I guess we could say knishes, certain reservoirs.
Can you explain a little bit more about what you mean by plague ending and how you measure the end if it ends continuously in the wildlife population?
Great gerbils is one of the species being the hosts of the U.S. hepatitis A bacterium in Central Asia.
And when condition over a large area is hot but not too hot, humid but not too humid,
then the German population grew to become larger and larger income above a certain threshold when it's above a certain threshold.
Abundance, I mean, how many there are, then it is likely that there might be a plague outbreak in the journal.
Then, yeah, if that stays on for a couple of years, then it's where you can have a plague outbreak,
then over the same a room if there suddenly becomes very dry condition.
So that is bad for the vegetation, bad for the flea, but for everybody, then the German population crashes.
And that is exactly the time when the German population crashes does when it spills over to the human population.
It is very interesting that now I. Know that the plague pandemic in the wildlife ends when it is dry condition,
whereas historians, they say that it starts in the human population when it is dry condition.
Of course it is because there's a spill-over. But that's a really fascinating point that, of course,
if you're looking at animal reservoirs and it's and say gerbil populations and how that relates to environmental conditions and climate and so on.
But what ends in the animal reservoir then, is when it starts in the human population.
So Barbara, you look more at human populations. So how do you see plague ending in those populations?
You need also to understand how it start, if it is because of contact with the animals of a reservoir,
you can have from time to time gain a new cases because of the contact can also be by chance.
But if you have an epidemic, you can see that you need to some particular condition, which are hygienic conditions, mostly and a control prevention.
We have studied the third plague pandemic in Europe, and we have clearly seen that that was introduced continuously from outside.
And this is because we have no plague reservoir in Europe so that the possibility to have some contact with the animals is going to reduce.
But the plague was introduced from outside. That was in the period at the end of the 19th century,
when people were very aware about importation of a new infectious disease during the 19th century was introduced to the referees,
and they have developed a good system to avoid the introduction of plague.
And then for, for instance, plague was became not feasible and internationally notifiable.
That means that all the people were aware about the possibility to import a plague.
So they have the situation under control and to have used a lot of measure to avoid the spread of of the contagion.
For instance, isolation of cases, information to the public and to the health care, sanitation and hygiene measures.
And in such a way, they have stopped the contagion.
And we have had during the third pandemic, only one large outbreak in Europe.
But all the other contagion or all the other outbreaks that were reduced in dimensions.
And from the beginning of the 1950s, we had the stop of the introduction of plague.
Also, because new measures were introduced and like the Hoover,
the washing machine and to have routine which could destroy parasites, which are the vector of the transmission of plague.
And yes, we are convinced that in the absence of a reservoir, this measure to stop a pandemic or an epidemic.
This is it's really fascinating to you,
and I think a good reminder to many of us because I'm sure many people watching and listening will think we'll associate plague with,
say, the Middle Ages and the Black Death. But of course, as you point out,
there's a third plague pandemic starting in the 1860s and that which continues on into various parts of the world in the 20th century.
And if I've understood your research correctly, as you both point out, that outbreak depends partly on climate and environmental conditions,
which also then affects animal reservoirs and in this case, journals, not just rats.
As people often talk about when we talk about plague and how those animal reservoirs interact.
And so for the third plague pandemic, it was the lack of an animal reservoir in Europe, but also the activities of human populations,
surveillance and monitoring and a focus on hygiene and sanitation, which meant that populations could control the outbreak of plague and then end it.
So if I've understood correctly, in order to understand plague,
we actually need a variety of disciplines because we need to understand all of these different arenas.
And that's also the only way that we can understand the end of an epidemic.
And it also sounds a bit like ways in which we talk about COVID 19.
Is that correct? The answer is, you know, I think the interdisciplinarity is the key here.
Now, Barbara's on my conclusion together with colleagues that plague must have come in to Europe several times from outside.
If you only look at the genetic information that the conclusion is that plague must have circulated around in Europe all along.
But if you include ecological historical archaeological information, then that's no longer clear.
Rather, the opposite that plague must have come in several times, and we have to remember that although plague has ended in Europe.
It is very active in many other parts of the world, in Central Asia, in Africa, in America.
There are plague outbreaks all along and the last one we had of a huge, huge epidemic was in Madagascar a few years ago.
So plague is a disease of today, but not in Europe, because we don't have the right conditions for plague,
the bacterium to circulate around what we live in the reservoir.
But that is very much debated in the scientific field.
I'm pretty sure we are onto the right answer.
It's always good to know that there's more research that can still be done, debates still to be had.
So thank you very much, Barbara, and thank you very much, Neal, for sharing your expertise with us.
And thank you all for watching our videos. Please do watch some of our other videos and please also do fill out a feedback form.
It only takes a few minutes of your time, and it helps to support research at the University of Oxford.
Thank you very much. Thank you. Thank you.