1 00:00:11,610 --> 00:00:16,500 Hello, welcome to the project, How Epidemics and which is based at the University of Oxford. 2 00:00:16,500 --> 00:00:23,370 My name is Erica Charters. And in these videos I discuss with researchers how they understand and analyse disease, 3 00:00:23,370 --> 00:00:27,660 as well as how they measure and understand the ending of epidemics. 4 00:00:27,660 --> 00:00:33,720 Today, I'm here with Llorens von Seidlin, who's an associate professor of epidemiology at the University of Oxford. 5 00:00:33,720 --> 00:00:41,040 He's also part of the Mardle Oxford Tropical Medicine Research Unit, which is based in Bangkok in Thailand. 6 00:00:41,040 --> 00:00:48,500 LLORENS, what drew you to epidemiology and to your field of infectious diseases? 7 00:00:48,500 --> 00:00:53,960 I was always kind of interested working in places like Africa and Asia, 8 00:00:53,960 --> 00:01:02,780 and I realised early on that the large majority of people in these countries are under 18 years of age, 9 00:01:02,780 --> 00:01:09,320 and the bulk of the diseases, if you work in a hospital, are infectious diseases in children. 10 00:01:09,320 --> 00:01:14,480 So to get the best training for that, for that work, 11 00:01:14,480 --> 00:01:21,710 I thought it would be a good idea to get training in infectious disease and infectious diseases, how to treat them. 12 00:01:21,710 --> 00:01:30,260 And then when you when you do this for long enough, you realise that you would like to prevent these diseases and find out a little bit 13 00:01:30,260 --> 00:01:35,780 more about them not to sit there every day and treat malaria or treat this media, 14 00:01:35,780 --> 00:01:43,850 but to think about how can I improve the treatment, but perhaps even more importantly, prevent children from coming in with these diseases. 15 00:01:43,850 --> 00:01:52,250 And then if you think about how do you do that best, you end up that you would like to do clinical studies, clinical trials, 16 00:01:52,250 --> 00:01:58,970 and to do this really professionally, to do it well enough that you get funding for it and that you can publish it. 17 00:01:58,970 --> 00:02:06,040 You need some training. And so I decided I would really like to get training in infectious disease epidemiology. 18 00:02:06,040 --> 00:02:11,410 So I think most people now probably know, thanks to covid about epidemiology, 19 00:02:11,410 --> 00:02:16,220 and they know that this means studying disease amongst populations, amongst large groups of people. 20 00:02:16,220 --> 00:02:21,100 But there's a variety of ways in which epidemiologists study disease. Some people do field work. 21 00:02:21,100 --> 00:02:30,020 Some people just deal with statistics. What kind of evidence, what types of sources do you use when you're conducting your research? 22 00:02:30,020 --> 00:02:33,590 And we do a lot of surveillance study to find out whether you see how the diseases 23 00:02:33,590 --> 00:02:41,450 are distributed and then we do try to do it randomised controlled trials, 24 00:02:41,450 --> 00:02:46,970 which is really the best evidence to see whether an intervention works or whether it doesn't work. 25 00:02:46,970 --> 00:02:52,970 And that's that's what we're doing. And we're doing this usually in countries where these diseases are, 26 00:02:52,970 --> 00:03:02,190 which are called neglected tropical diseases, and that's in low income countries in Asia and in Africa. 27 00:03:02,190 --> 00:03:07,880 And so basically, you're looking at very large, large numbers when you do your clinical trials, 28 00:03:07,880 --> 00:03:14,060 large groups of populations and in some ways comparing and contrasting treatments as well as tracking disease rates. 29 00:03:14,060 --> 00:03:20,400 Is that right? If you want to get an understanding how a disease develops in a population, 30 00:03:20,400 --> 00:03:28,140 obviously you need huge surveillance and the more people you enrol in a study into the broader surveillance is, 31 00:03:28,140 --> 00:03:35,590 the higher the certainty is that your results are relatively correct. So that's why we would like to do massive studies on the demand side. 32 00:03:35,590 --> 00:03:41,220 What is counter-intuitive about it is because if you have an idea and you would like to test it, 33 00:03:41,220 --> 00:03:46,590 ideally you would like to do this in a small setting in the first place and not risk too much, right? 34 00:03:46,590 --> 00:03:55,050 Only on one hundred people. But if you do a small study in 100 people, it's not very generalisable and it's there's a lot of uncertainty. 35 00:03:55,050 --> 00:04:03,160 In contrast, if you do a study on 10000 people or even a hundred thousand people, you can detect a very small effect with high precision. 36 00:04:03,160 --> 00:04:06,870 That's why you would like to do it in massive populations. 37 00:04:06,870 --> 00:04:13,440 Basically, the problem is that if you do it in a massive population, you need a completely different logistics. 38 00:04:13,440 --> 00:04:19,950 You need you need people who collect the data and work with data, who can do statistics and so on. 39 00:04:19,950 --> 00:04:24,000 And to do this, you need a lot of funding to to pay everybody, basically. 40 00:04:24,000 --> 00:04:28,650 And then to get the funding, you have to get into the politics to get the funding. 41 00:04:28,650 --> 00:04:31,260 So it becomes really, really much more complicated. 42 00:04:31,260 --> 00:04:36,180 So on the one hand side, you would really like to do something small and cheap and quick, but on the other hand, 43 00:04:36,180 --> 00:04:42,600 to do it with high precision and to get it right, you have to do it massively and big and it takes a long time. 44 00:04:42,600 --> 00:04:48,600 So I know you've looked at a range of diseases when you're thinking about disease amongst these large populations. 45 00:04:48,600 --> 00:04:52,440 You've looked at malaria for a long time. Most recently, it looks at covid. 46 00:04:52,440 --> 00:05:00,360 You've also works on cholera. And as you mentioned, these are considered they're sometimes called neglected diseases. 47 00:05:00,360 --> 00:05:05,220 What does it mean to be a neglected disease and what way are they neglected? 48 00:05:05,220 --> 00:05:06,480 It's a little bit difficult. 49 00:05:06,480 --> 00:05:11,630 And I don't know the history where this word comes from, the word neglected diseases that didn't look that up in the research. 50 00:05:11,630 --> 00:05:20,640 It not for me. It came mostly that a lot of doctors are drawn to people who have a lot of money. 51 00:05:20,640 --> 00:05:26,820 And the richest people, the most affluent people have cardiovascular diseases, for example. 52 00:05:26,820 --> 00:05:32,730 And so there's a lot of money for research in that field. And then everybody who works on other diseases, like, for example, 53 00:05:32,730 --> 00:05:38,760 infectious diseases in children in low income countries, of course, thinks a lot in comparison to discuss unlikely. 54 00:05:38,760 --> 00:05:43,860 And then there was a Journal of PLoS neglected diseases. 55 00:05:43,860 --> 00:05:49,380 And so it became very clear that a certain group of diseases belongs in there. 56 00:05:49,380 --> 00:05:57,630 And who defines this is another question. And then the other development was that after 95, between 95 and 2000, 57 00:05:57,630 --> 00:06:04,950 Bill Gates came into the field and Sandy had a lot of money and he said, I'm investing money into neglected diseases. 58 00:06:04,950 --> 00:06:11,580 So suddenly it became particularly attractive to have that label because you could apply for funding from the Gates Foundation. 59 00:06:11,580 --> 00:06:15,970 And so this is multiple influences are taking place at the same time. 60 00:06:15,970 --> 00:06:20,050 So a lot of people are sick of my diseases and neglected diseases. There's no, no, no. 61 00:06:20,050 --> 00:06:24,200 This is not an exact disease. You're wrong about this. So it has changed. 62 00:06:24,200 --> 00:06:32,610 It's a little bit fluid, but I think both cholera and malaria can be still labelled neglected diseases. 63 00:06:32,610 --> 00:06:37,870 Even so, the billions of dollars and have have gone into malaria in the last 20 years. 64 00:06:37,870 --> 00:06:42,060 I mean, my other senses, when we think about where those diseases still occur, 65 00:06:42,060 --> 00:06:48,000 even though they were common throughout much of the world by the end of the 19th century and really into the 20th century, 66 00:06:48,000 --> 00:06:54,510 malaria and cholera are diseases we only really see in the developing world. 67 00:06:54,510 --> 00:07:02,220 We don't see them so much and the industrialised world. So they tend to be diseases that are tied to poverty and to certain geographies as well. 68 00:07:02,220 --> 00:07:07,200 So for people who don't know, can you explain a bit about a disease such as cholera, 69 00:07:07,200 --> 00:07:14,670 which is very often linked to wars and to poverty and to a lack of infrastructure, how does it spread? 70 00:07:14,670 --> 00:07:27,240 What are its symptoms? You know more about the history of colour than I do, because your own story and for me it kind of sort of started 1970s, 1960s, 71 00:07:27,240 --> 00:07:34,740 and the home of colour was really considered the Bay of Bengal, particularly Bangladesh, that was considered the homeland of cholera. 72 00:07:34,740 --> 00:07:39,690 And then it has been over the last 50 years, increasingly controlled in Bangladesh. 73 00:07:39,690 --> 00:07:43,710 It isn't so much anymore, but then it has migrated to Africa. 74 00:07:43,710 --> 00:07:52,080 Then there was an outbreak in South America, Peru, particularly when there was a massive outbreak in Haiti and now probably the centres Yemen, 75 00:07:52,080 --> 00:07:58,080 because there's a war going on and that has destroyed the entire water supply and sanitation. 76 00:07:58,080 --> 00:08:02,460 And there are a lot of cases now reported Yemen probably more than from anywhere else. 77 00:08:02,460 --> 00:08:16,860 So it's outbreaks in different places. But there was a clear shift from Africa to sub-Saharan Africa because in Bangladesh it's assumed that the 78 00:08:16,860 --> 00:08:22,020 water supply and sanitation are improving to a level which is no longer sustaining cholera transmission. 79 00:08:22,020 --> 00:08:32,430 But you have a good environment for that in sub-Saharan Africa. So very much tied to water supplies, to sanitation and some to basic hygiene. 80 00:08:32,430 --> 00:08:36,800 That's a water supply. And sanitation for most people comes even before Internet. 81 00:08:36,800 --> 00:08:42,950 Believe it or not. It's it's it's probably with social media on the same level as important. 82 00:08:42,950 --> 00:08:49,580 And so a lot of people when the first thing is that you have a roof over your head, but then you get a safe water supply. 83 00:08:49,580 --> 00:08:59,900 And a lot of people need help with this because it's not not easy to for yourself if you have nothing to get to a safe water supply and to sanitation. 84 00:08:59,900 --> 00:09:06,710 And I know that you're actually working on or you're part of what is a global programme right now to eliminate cholera. 85 00:09:06,710 --> 00:09:12,500 So how will you know as an epidemiologist, how will you know when cholera is eliminated? 86 00:09:12,500 --> 00:09:20,180 What kind of what things are you measuring? So what to do is, for example, what we did in Mozambique, 87 00:09:20,180 --> 00:09:27,140 in Beirut during the surveillance for for trial that we tested this could oral cholera vaccine is we are 88 00:09:27,140 --> 00:09:34,040 looking every day how many cases are reported in our reporting system and then say you have every day 100, 89 00:09:34,040 --> 00:09:37,370 120, 140, 150 and so on. 90 00:09:37,370 --> 00:09:40,550 Do you see that it's slightly going up? You know, it's it's increasing. 91 00:09:40,550 --> 00:09:48,650 And then comes a point sometime and we can talk about why it has to go down again and it slowly goes down. 92 00:09:48,650 --> 00:09:54,980 And then at some point you have 50, 30, 40, and then you have only one or two cases. 93 00:09:54,980 --> 00:10:00,500 And then finally you have nothing anymore. And that is pretty predictable as happens like that. 94 00:10:00,500 --> 00:10:08,990 So it can still happen that there are some time out, that there is still you know, there are five cases in a week and two and then five again. 95 00:10:08,990 --> 00:10:13,370 So it goes along. It hasn't really completely stopped. 96 00:10:13,370 --> 00:10:20,340 So if you really want to see when has it stopped, you have to wait for a year and then look back at the epidemic curve and see then what's the point? 97 00:10:20,340 --> 00:10:29,000 And then nothing was reported anymore for four months. If you want to use that as a criterion and say, OK, so this must have been the time it stopped. 98 00:10:29,000 --> 00:10:34,340 But while you are sitting there, you said, OK, this week we only had one case. 99 00:10:34,340 --> 00:10:39,230 It's really difficult to say that the outbreak has stopped because you can't predict the future. 100 00:10:39,230 --> 00:10:46,640 So it is something that you decide in retrospect. You look back and say, OK, this is must have been the first time stuff. 101 00:10:46,640 --> 00:10:49,070 But I imagine also it must be very difficult, 102 00:10:49,070 --> 00:10:56,720 especially if we're talking about outbreaks that often happen during wars, during breakdowns to get reliable data. 103 00:10:56,720 --> 00:11:02,690 Is it easy to to get data on cases of cholera? 104 00:11:02,690 --> 00:11:08,210 Particularly interesting to see, because it's so stigmatised, it's associated with poverty, 105 00:11:08,210 --> 00:11:12,320 with the absence of safe water supply and sanitation, which nobody wants. 106 00:11:12,320 --> 00:11:16,460 So for a government to admit that they have cholera cases is a bad thing. 107 00:11:16,460 --> 00:11:20,790 And in many countries, particularly in Asia, and governments wouldn't like to admit this, 108 00:11:20,790 --> 00:11:24,760 so they call them watery diarrhoea cases don't report them as cholera. 109 00:11:24,760 --> 00:11:30,110 It's just it's not good for tourism, that's for sure. And it's not good for investment in the country. 110 00:11:30,110 --> 00:11:34,250 So the leadership, the government usually doesn't want to report it. 111 00:11:34,250 --> 00:11:40,400 On the other hand, said if you are in a in a war situation, in a really difficult situation, 112 00:11:40,400 --> 00:11:45,470 like, for example, that was the case in Mozambique, you're starting to bring it up. 113 00:11:45,470 --> 00:11:52,610 Where do we get more money from development if you're a part of a lot of cases, or do we get more cases if you report no more cases, 114 00:11:52,610 --> 00:11:57,410 indeed, cholera is controlled and and tourism should come back into our country. 115 00:11:57,410 --> 00:12:02,270 So these are two political influences which which which are sitting on you. 116 00:12:02,270 --> 00:12:10,910 But if you are a relatively independent researcher working in a place like Canberra, you can be had no problem reporting the cases that we found. 117 00:12:10,910 --> 00:12:18,050 But the cases that we find in a setting like this are only the ones which come to us in that 118 00:12:18,050 --> 00:12:25,230 place where there was a cholera treatment centre and everybody living in the province knew. 119 00:12:25,230 --> 00:12:30,180 If you have cholera and you want to survive severe cholera, you have to go to this point. 120 00:12:30,180 --> 00:12:34,620 They won't let you into any other hospital because they don't want contamination in the other hospitals. 121 00:12:34,620 --> 00:12:42,390 You have to come to the cholera treatment centre in the middle of town, which was exclusively dealing with watery diarrhoea cases. 122 00:12:42,390 --> 00:12:46,910 And they have had these books and everybody who came in was written into it. 123 00:12:46,910 --> 00:12:51,690 The next morning, one of our guys would come in the copy, the names, and then entered into the computer. 124 00:12:51,690 --> 00:12:56,470 So we would know every day how many people came into the cholera treatment centre. 125 00:12:56,470 --> 00:13:01,260 But you rightly say so what happens to the people in the future either to come into the cholera 126 00:13:01,260 --> 00:13:07,700 treatment centre or people who don't have enough money to get there or to seek to get them? 127 00:13:07,700 --> 00:13:18,350 So as well as as as needing all this data and in some ways having centres such as that, what is required to eliminate cholera, which we need to do? 128 00:13:18,350 --> 00:13:27,530 And so give me a second. Let me talk about this elimination, which is a geographical area when you get rid of it, and then there's eradication, 129 00:13:27,530 --> 00:13:35,390 which means you get rid of it from the whole planet and people would like to eradicate cholera, which would be a great thing. 130 00:13:35,390 --> 00:13:44,960 But there are people like Taco Bell who found that zooplankton which is in the ocean, can become infected with cholera and carry it. 131 00:13:44,960 --> 00:13:49,340 And once you have an animal host out there, 132 00:13:49,340 --> 00:13:56,030 it becomes really difficult to to think about eradicating it because they will it's very difficult 133 00:13:56,030 --> 00:14:00,140 to imagine a situation that everybody on the boat has a safe water supply and sanitation. 134 00:14:00,140 --> 00:14:03,920 And if some person like this comes in contact with it, it will be there again. 135 00:14:03,920 --> 00:14:11,690 Cholera will get into the human population again. There's no question you can eliminate it from a relatively limited area. 136 00:14:11,690 --> 00:14:19,250 And this improvement of water supply and sanitation, that's the long term strategy, would meet it in Cairo, for example. 137 00:14:19,250 --> 00:14:24,640 And there was a crisis situation that we saw in the first instance. We would like to vaccinate everybody now. 138 00:14:24,640 --> 00:14:32,060 We would like to do mass vaccination campaign. And a lot of people understand what I mean by that, because it's the same with Corbitt, right? 139 00:14:32,060 --> 00:14:37,070 So things have changed a little bit more of an unusual idea 15 years ago. 140 00:14:37,070 --> 00:14:42,920 So you go in there, you tell the whole community, you know what cholera is, you're scared of it. 141 00:14:42,920 --> 00:14:51,680 We are bringing cholera vaccine in here. We're opening these mass vaccination centres and everybody can come in and can get vaccinated. 142 00:14:51,680 --> 00:15:02,480 And that's great. And it really suppresses an outbreak. But the vaccine only gives you immunity for, say, two years just as a rough measure. 143 00:15:02,480 --> 00:15:06,700 And you are susceptible again after two months. So basically you gain then two years. 144 00:15:06,700 --> 00:15:11,120 Maybe you should set up a water supply and sanitation. If you don't do this in the two years, 145 00:15:11,120 --> 00:15:18,470 I think it will repeat and your mass vaccination campaigns on approach to selectively or you do something more 146 00:15:18,470 --> 00:15:24,860 permanent and really work on your water supply and sanitation and get that going in the in the time this. 147 00:15:24,860 --> 00:15:29,440 But you have to have communities. 148 00:15:29,440 --> 00:15:35,380 So and I know that there's been a number, as you say, of these elimination programmes thinking regionally and I know that you're working, 149 00:15:35,380 --> 00:15:43,750 especially in Southeast Asia right now, some of the global programmes for eliminating cholera started, I believe, back in the 1990s. 150 00:15:43,750 --> 00:15:51,700 So how close are we right now in twenty, twenty one to eliminating cholera in these regions? 151 00:15:51,700 --> 00:15:56,840 I think the big spenders in the market have these huge outbreaks. 152 00:15:56,840 --> 00:16:05,980 It was a huge one. And that was thought to be imparted from a person from East Asia working for the United Nations for 153 00:16:05,980 --> 00:16:13,570 the what would you call these troops that they are sending with the United Nations emergency troops? 154 00:16:13,570 --> 00:16:18,880 And they were stationed in Haiti and the sanitation wasn't satisfactory. 155 00:16:18,880 --> 00:16:24,610 So the people there basically had the raw sewage going into a river, which then used this water supply. 156 00:16:24,610 --> 00:16:35,740 And we assume that one or more of these people in the United Nations contingent was infected and transmitted cholera to the local people. 157 00:16:35,740 --> 00:16:42,910 So you can easily transplant something from from one place nowadays with a 12 hour flight to another place. 158 00:16:42,910 --> 00:16:49,150 If sanitation at the other end is not satisfactory, that person comes to New York. 159 00:16:49,150 --> 00:16:51,400 It's very unlikely that it causes an outbreak. 160 00:16:51,400 --> 00:16:58,270 But if that person ends up in Haiti and nobody has taken care of the sanitation properly, then you have another outbreak. 161 00:16:58,270 --> 00:17:04,780 The other that that outbreak is now declined much better control. 162 00:17:04,780 --> 00:17:10,540 The big problem at the moment is Yemen, where, you know, there's a warfare ongoing, 163 00:17:10,540 --> 00:17:15,460 Saudi Arabia and the United States involved and so on, a very complicated situation. 164 00:17:15,460 --> 00:17:21,430 And that wasn't going on. They report a lot of watery diarrhoea and a lot of cholera cases that are still. 165 00:17:21,430 --> 00:17:31,600 And of course, the underlying problem is that if you even if you construct a water supply system and sewerage and it gets pumped the next day, 166 00:17:31,600 --> 00:17:36,640 you have nothing. And that seems to have happened repeatedly over and over and over again. 167 00:17:36,640 --> 00:17:45,470 So the solution for that is you can do mass vaccination campaigns to the point that there is. 168 00:17:45,470 --> 00:17:53,120 If you have enough time to construct a safe water supply and sanitation, that that is probably the only way to. 169 00:17:53,120 --> 00:17:58,310 To deal with that, to solve that problem, to get control in Yemen over over control, 170 00:17:58,310 --> 00:18:03,290 but nevertheless, I mean, there is there will be another outbreak, I would I would predict. 171 00:18:03,290 --> 00:18:10,130 So the chances of really eradicating it globally are not very high. 172 00:18:10,130 --> 00:18:12,860 But I'm impressed that you're still working on this, 173 00:18:12,860 --> 00:18:19,010 and I wish you very well on your research as you continue to tackle diseases such as cholera and malaria. 174 00:18:19,010 --> 00:18:23,690 Thank you very much for sharing your expertise with us, Lawrence, and thank you all for joining us. 175 00:18:23,690 --> 00:18:35,284 And I hope that you'll join us with some of the other interviews and videos.