1 00:00:11,570 --> 00:00:16,760 Hello and welcome to the how epidemics and projects based at the University of Oxford. 2 00:00:16,760 --> 00:00:23,660 My name is Erica Chalmers, and in these videos, I discuss how experts research disease in a variety of ways, 3 00:00:23,660 --> 00:00:26,810 as well as their investigations into how epidemics. 4 00:00:26,810 --> 00:00:34,910 And today I'm here with two scientists who study human evolution and ecology in the way that they study disease. 5 00:00:34,910 --> 00:00:38,270 So I have here with me Miles Christian Stenson, 6 00:00:38,270 --> 00:00:45,320 who's professor of ecology and evolution at the University of Oslo and who's an evolutionary biologist and ecologist. 7 00:00:45,320 --> 00:00:47,720 And I also have with me Barbara Bramante, 8 00:00:47,720 --> 00:00:54,680 who's associate professor at the Department of Environmental and Prevention Sciences at the University of Ferrara in Italy, 9 00:00:54,680 --> 00:00:57,530 who's a physical anthropologist. 10 00:00:57,530 --> 00:01:06,830 So IRA animals, I think people might have a general idea about human evolution and how it relates to ecology and to the environment. 11 00:01:06,830 --> 00:01:16,760 But can you explain a little bit more specifically how you, as an evolutionary biologist and as physical anthropologists, study disease? 12 00:01:16,760 --> 00:01:23,480 So, Niels, if we're to start with you, do you work in a lab in field, work on a computer? 13 00:01:23,480 --> 00:01:34,160 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. 14 00:01:34,160 --> 00:01:36,770 So observations over many years. 15 00:01:36,770 --> 00:01:49,490 And when I first got into plague work, it was analysing data from the old Soviet Union about recording occurrence of played in wildlife. 16 00:01:49,490 --> 00:01:58,850 We have to remember that the plague caused by your son pestis is a wildlife disease that occasionally spills over to the human population. 17 00:01:58,850 --> 00:02:06,200 And as a matter of fact, it spills over to the human population when plague in wildlife and elsewhere. 18 00:02:06,200 --> 00:02:14,000 So I'm analysing these kind of data. What is the what is the structure or the dynamics in space and time? 19 00:02:14,000 --> 00:02:21,200 And I do statistical models based on really population mathematical population models. 20 00:02:21,200 --> 00:02:26,350 So that's what I do for a living. That's very that's very helpful. 21 00:02:26,350 --> 00:02:31,510 And, Barbara, I know in some ways you also look at but from a slightly different angles. 22 00:02:31,510 --> 00:02:37,280 Can you explain how your research works when you do physical anthropology? 23 00:02:37,280 --> 00:02:50,480 Yes. I'm a physical anthropologist year have said that mindset that I am interested in human evolution and in 24 00:02:50,480 --> 00:03:03,050 terms of population dynamics and in terms of human environmental interactions and since disease part, 25 00:03:03,050 --> 00:03:11,960 especially infectious disease, that's part of this interaction between humans and the natural environment. 26 00:03:11,960 --> 00:03:19,630 I am also very interested in this kind of infectious disease and in particular on plague. 27 00:03:19,630 --> 00:03:39,500 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. 28 00:03:39,500 --> 00:03:41,720 And from this point on, 29 00:03:41,720 --> 00:03:58,440 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. 30 00:03:58,440 --> 00:04:04,360 So this is really interesting, because, of course, the two of you work together and I know you work with many other researchers. 31 00:04:04,360 --> 00:04:10,890 So can you explain a little bit more about how then you study flag when you're working together? 32 00:04:10,890 --> 00:04:17,370 Niels, you've talked a lot about how you're part of the centre that brings together different disciplines at the University of Oslo. 33 00:04:17,370 --> 00:04:22,460 Explain a little bit about your research and how it works with purpose research. What have been some of your findings? 34 00:04:22,460 --> 00:04:33,960 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, 35 00:04:33,960 --> 00:04:36,900 you know, superficially, the right condition. 36 00:04:36,900 --> 00:04:46,560 However, we did a paper not with Barbara, but with other colleagues here that was published in 2000 and 14 or 15. 37 00:04:46,560 --> 00:04:53,400 I believe where we demonstrated that the occurrence of plague in harbour cities in 38 00:04:53,400 --> 00:05:00,870 Europe was linked to good plague conditions in Central Asia several years earlier. 39 00:05:00,870 --> 00:05:07,920 So then I became convinced that as a matter of fact, plague must have come into Europe several times. 40 00:05:07,920 --> 00:05:14,760 And then Barbara was the obvious partner for linking up here because she was 41 00:05:14,760 --> 00:05:22,350 studying the genetics of old skeletons or actually the teeth of the skeleton, 42 00:05:22,350 --> 00:05:28,410 and you can expand as much better on myself. Yeah, and that's the work that Barbara did. 43 00:05:28,410 --> 00:05:37,500 And Barbara, we did together really support our original idea that plague must have come in several times to Europe. 44 00:05:37,500 --> 00:05:39,690 So that's really where we met. 45 00:05:39,690 --> 00:05:50,070 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. 46 00:05:50,070 --> 00:05:55,460 Her project was really spot on to answer that question. 47 00:05:55,460 --> 00:05:58,940 I think this is a really interesting point, and Barbara, I want you to expand a bit on this, 48 00:05:58,940 --> 00:06:03,320 but especially thinking about what kind of sources and data you're looking at, 49 00:06:03,320 --> 00:06:09,980 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. 50 00:06:09,980 --> 00:06:17,900 So the records that humans are writing and leaving behind, but you seem to be looking at different types of sources to study alongside. 51 00:06:17,900 --> 00:06:21,410 So, Barbara, what kind of sources than are you looking at? 52 00:06:21,410 --> 00:06:30,390 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? 53 00:06:30,390 --> 00:06:44,490 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, 54 00:06:44,490 --> 00:06:55,470 ancient DNA from the teeth and to reconstruct the genomes of the ancient bacteria and to compare them. 55 00:06:55,470 --> 00:07:07,090 And by doing so, we can reconstruct also the phylogenetic three of the bacteria, and we can better understand the dynamics. 56 00:07:07,090 --> 00:07:15,360 But the phylogenetic tree is not so easy to be interpreted, and we need also other kinds of data. 57 00:07:15,360 --> 00:07:28,470 And this is also the reason because of these interactions, very fruitful interaction with ecologists and archaeologists. 58 00:07:28,470 --> 00:07:36,210 We need a lot of competences, of course. Also, the storm comes because we have always the eastern evidence, 59 00:07:36,210 --> 00:07:44,020 historical evidence in the background of when we try to interpret data, find a genetic tree. 60 00:07:44,020 --> 00:07:52,720 So unless you've already mentioned something about plague ending the plague ending only in certain groups or certain, 61 00:07:52,720 --> 00:07:55,540 I guess we could say knishes, certain reservoirs. 62 00:07:55,540 --> 00:08:05,440 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? 63 00:08:05,440 --> 00:08:13,660 Great gerbils is one of the species being the hosts of the U.S. hepatitis A bacterium in Central Asia. 64 00:08:13,660 --> 00:08:23,500 And when condition over a large area is hot but not too hot, humid but not too humid, 65 00:08:23,500 --> 00:08:34,030 then the German population grew to become larger and larger income above a certain threshold when it's above a certain threshold. 66 00:08:34,030 --> 00:08:43,640 Abundance, I mean, how many there are, then it is likely that there might be a plague outbreak in the journal. 67 00:08:43,640 --> 00:08:51,620 Then, yeah, if that stays on for a couple of years, then it's where you can have a plague outbreak, 68 00:08:51,620 --> 00:08:57,380 then over the same a room if there suddenly becomes very dry condition. 69 00:08:57,380 --> 00:09:04,400 So that is bad for the vegetation, bad for the flea, but for everybody, then the German population crashes. 70 00:09:04,400 --> 00:09:12,410 And that is exactly the time when the German population crashes does when it spills over to the human population. 71 00:09:12,410 --> 00:09:25,160 It is very interesting that now I. Know that the plague pandemic in the wildlife ends when it is dry condition, 72 00:09:25,160 --> 00:09:31,460 whereas historians, they say that it starts in the human population when it is dry condition. 73 00:09:31,460 --> 00:09:37,660 Of course it is because there's a spill-over. But that's a really fascinating point that, of course, 74 00:09:37,660 --> 00:09:45,520 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. 75 00:09:45,520 --> 00:09:50,600 But what ends in the animal reservoir then, is when it starts in the human population. 76 00:09:50,600 --> 00:10:02,300 So Barbara, you look more at human populations. So how do you see plague ending in those populations? 77 00:10:02,300 --> 00:10:13,280 You need also to understand how it start, if it is because of contact with the animals of a reservoir, 78 00:10:13,280 --> 00:10:25,010 you can have from time to time gain a new cases because of the contact can also be by chance. 79 00:10:25,010 --> 00:10:45,170 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. 80 00:10:45,170 --> 00:10:56,090 We have studied the third plague pandemic in Europe, and we have clearly seen that that was introduced continuously from outside. 81 00:10:56,090 --> 00:11:08,460 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. 82 00:11:08,460 --> 00:11:15,890 But the plague was introduced from outside. That was in the period at the end of the 19th century, 83 00:11:15,890 --> 00:11:29,390 when people were very aware about importation of a new infectious disease during the 19th century was introduced to the referees, 84 00:11:29,390 --> 00:11:37,400 and they have developed a good system to avoid the introduction of plague. 85 00:11:37,400 --> 00:11:48,080 And then for, for instance, plague was became not feasible and internationally notifiable. 86 00:11:48,080 --> 00:11:55,370 That means that all the people were aware about the possibility to import a plague. 87 00:11:55,370 --> 00:12:10,640 So they have the situation under control and to have used a lot of measure to avoid the spread of of the contagion. 88 00:12:10,640 --> 00:12:23,420 For instance, isolation of cases, information to the public and to the health care, sanitation and hygiene measures. 89 00:12:23,420 --> 00:12:28,100 And in such a way, they have stopped the contagion. 90 00:12:28,100 --> 00:12:34,610 And we have had during the third pandemic, only one large outbreak in Europe. 91 00:12:34,610 --> 00:12:43,550 But all the other contagion or all the other outbreaks that were reduced in dimensions. 92 00:12:43,550 --> 00:12:56,570 And from the beginning of the 1950s, we had the stop of the introduction of plague. 93 00:12:56,570 --> 00:13:03,590 Also, because new measures were introduced and like the Hoover, 94 00:13:03,590 --> 00:13:15,590 the washing machine and to have routine which could destroy parasites, which are the vector of the transmission of plague. 95 00:13:15,590 --> 00:13:28,200 And yes, we are convinced that in the absence of a reservoir, this measure to stop a pandemic or an epidemic. 96 00:13:28,200 --> 00:13:30,030 This is it's really fascinating to you, 97 00:13:30,030 --> 00:13:36,180 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, 98 00:13:36,180 --> 00:13:39,630 say, the Middle Ages and the Black Death. But of course, as you point out, 99 00:13:39,630 --> 00:13:47,490 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. 100 00:13:47,490 --> 00:13:56,700 And if I've understood your research correctly, as you both point out, that outbreak depends partly on climate and environmental conditions, 101 00:13:56,700 --> 00:14:01,650 which also then affects animal reservoirs and in this case, journals, not just rats. 102 00:14:01,650 --> 00:14:06,760 As people often talk about when we talk about plague and how those animal reservoirs interact. 103 00:14:06,760 --> 00:14:15,420 And so for the third plague pandemic, it was the lack of an animal reservoir in Europe, but also the activities of human populations, 104 00:14:15,420 --> 00:14:26,400 surveillance and monitoring and a focus on hygiene and sanitation, which meant that populations could control the outbreak of plague and then end it. 105 00:14:26,400 --> 00:14:29,550 So if I've understood correctly, in order to understand plague, 106 00:14:29,550 --> 00:14:36,030 we actually need a variety of disciplines because we need to understand all of these different arenas. 107 00:14:36,030 --> 00:14:40,740 And that's also the only way that we can understand the end of an epidemic. 108 00:14:40,740 --> 00:14:45,360 And it also sounds a bit like ways in which we talk about COVID 19. 109 00:14:45,360 --> 00:14:51,650 Is that correct? The answer is, you know, I think the interdisciplinarity is the key here. 110 00:14:51,650 --> 00:15:00,000 Now, Barbara's on my conclusion together with colleagues that plague must have come in to Europe several times from outside. 111 00:15:00,000 --> 00:15:09,540 If you only look at the genetic information that the conclusion is that plague must have circulated around in Europe all along. 112 00:15:09,540 --> 00:15:16,020 But if you include ecological historical archaeological information, then that's no longer clear. 113 00:15:16,020 --> 00:15:26,480 Rather, the opposite that plague must have come in several times, and we have to remember that although plague has ended in Europe. 114 00:15:26,480 --> 00:15:34,850 It is very active in many other parts of the world, in Central Asia, in Africa, in America. 115 00:15:34,850 --> 00:15:44,780 There are plague outbreaks all along and the last one we had of a huge, huge epidemic was in Madagascar a few years ago. 116 00:15:44,780 --> 00:15:52,220 So plague is a disease of today, but not in Europe, because we don't have the right conditions for plague, 117 00:15:52,220 --> 00:15:56,270 the bacterium to circulate around what we live in the reservoir. 118 00:15:56,270 --> 00:16:00,320 But that is very much debated in the scientific field. 119 00:16:00,320 --> 00:16:06,400 I'm pretty sure we are onto the right answer. 120 00:16:06,400 --> 00:16:10,670 It's always good to know that there's more research that can still be done, debates still to be had. 121 00:16:10,670 --> 00:16:16,280 So thank you very much, Barbara, and thank you very much, Neal, for sharing your expertise with us. 122 00:16:16,280 --> 00:16:22,490 And thank you all for watching our videos. 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