Hello, welcome to the project, How Epidemics and which is based at the University of Oxford.
My name is Erica Charters. And in these videos I discuss with researchers how they understand and analyse disease,
as well as how they measure and understand the ending of epidemics.
Today, I'm here with Llorens von Seidlin, who's an associate professor of epidemiology at the University of Oxford.
He's also part of the Mardle Oxford Tropical Medicine Research Unit, which is based in Bangkok in Thailand.
LLORENS, what drew you to epidemiology and to your field of infectious diseases?
I was always kind of interested working in places like Africa and Asia,
and I realised early on that the large majority of people in these countries are under 18 years of age,
and the bulk of the diseases, if you work in a hospital, are infectious diseases in children.
So to get the best training for that, for that work,
I thought it would be a good idea to get training in infectious disease and infectious diseases, how to treat them.
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
more about them not to sit there every day and treat malaria or treat this media,
but to think about how can I improve the treatment, but perhaps even more importantly, prevent children from coming in with these diseases.
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,
and to do this really professionally, to do it well enough that you get funding for it and that you can publish it.
You need some training. And so I decided I would really like to get training in infectious disease epidemiology.
So I think most people now probably know, thanks to covid about epidemiology,
and they know that this means studying disease amongst populations, amongst large groups of people.
But there's a variety of ways in which epidemiologists study disease. Some people do field work.
Some people just deal with statistics. What kind of evidence, what types of sources do you use when you're conducting your research?
And we do a lot of surveillance study to find out whether you see how the diseases
are distributed and then we do try to do it randomised controlled trials,
which is really the best evidence to see whether an intervention works or whether it doesn't work.
And that's that's what we're doing. And we're doing this usually in countries where these diseases are,
which are called neglected tropical diseases, and that's in low income countries in Asia and in Africa.
And so basically, you're looking at very large, large numbers when you do your clinical trials,
large groups of populations and in some ways comparing and contrasting treatments as well as tracking disease rates.
Is that right? If you want to get an understanding how a disease develops in a population,
obviously you need huge surveillance and the more people you enrol in a study into the broader surveillance is,
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.
What is counter-intuitive about it is because if you have an idea and you would like to test it,
ideally you would like to do this in a small setting in the first place and not risk too much, right?
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.
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.
That's why you would like to do it in massive populations.
Basically, the problem is that if you do it in a massive population, you need a completely different logistics.
You need you need people who collect the data and work with data, who can do statistics and so on.
And to do this, you need a lot of funding to to pay everybody, basically.
And then to get the funding, you have to get into the politics to get the funding.
So it becomes really, really much more complicated.
So on the one hand side, you would really like to do something small and cheap and quick, but on the other hand,
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.
So I know you've looked at a range of diseases when you're thinking about disease amongst these large populations.
You've looked at malaria for a long time. Most recently, it looks at covid.
You've also works on cholera. And as you mentioned, these are considered they're sometimes called neglected diseases.
What does it mean to be a neglected disease and what way are they neglected?
It's a little bit difficult.
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.
It not for me. It came mostly that a lot of doctors are drawn to people who have a lot of money.
And the richest people, the most affluent people have cardiovascular diseases, for example.
And so there's a lot of money for research in that field. And then everybody who works on other diseases, like, for example,
infectious diseases in children in low income countries, of course, thinks a lot in comparison to discuss unlikely.
And then there was a Journal of PLoS neglected diseases.
And so it became very clear that a certain group of diseases belongs in there.
And who defines this is another question. And then the other development was that after 95, between 95 and 2000,
Bill Gates came into the field and Sandy had a lot of money and he said, I'm investing money into neglected diseases.
So suddenly it became particularly attractive to have that label because you could apply for funding from the Gates Foundation.
And so this is multiple influences are taking place at the same time.
So a lot of people are sick of my diseases and neglected diseases. There's no, no, no.
This is not an exact disease. You're wrong about this. So it has changed.
It's a little bit fluid, but I think both cholera and malaria can be still labelled neglected diseases.
Even so, the billions of dollars and have have gone into malaria in the last 20 years.
I mean, my other senses, when we think about where those diseases still occur,
even though they were common throughout much of the world by the end of the 19th century and really into the 20th century,
malaria and cholera are diseases we only really see in the developing world.
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.
So for people who don't know, can you explain a bit about a disease such as cholera,
which is very often linked to wars and to poverty and to a lack of infrastructure, how does it spread?
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,
and the home of colour was really considered the Bay of Bengal, particularly Bangladesh, that was considered the homeland of cholera.
And then it has been over the last 50 years, increasingly controlled in Bangladesh.
It isn't so much anymore, but then it has migrated to Africa.
Then there was an outbreak in South America, Peru, particularly when there was a massive outbreak in Haiti and now probably the centres Yemen,
because there's a war going on and that has destroyed the entire water supply and sanitation.
And there are a lot of cases now reported Yemen probably more than from anywhere else.
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
water supply and sanitation are improving to a level which is no longer sustaining cholera transmission.
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.
That's a water supply. And sanitation for most people comes even before Internet.
Believe it or not. It's it's it's probably with social media on the same level as important.
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.
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.
And I know that you're actually working on or you're part of what is a global programme right now to eliminate cholera.
So how will you know as an epidemiologist, how will you know when cholera is eliminated?
What kind of what things are you measuring? So what to do is, for example, what we did in Mozambique,
in Beirut during the surveillance for for trial that we tested this could oral cholera vaccine is we are
looking every day how many cases are reported in our reporting system and then say you have every day 100,
120, 140, 150 and so on.
Do you see that it's slightly going up? You know, it's it's increasing.
And then comes a point sometime and we can talk about why it has to go down again and it slowly goes down.
And then at some point you have 50, 30, 40, and then you have only one or two cases.
And then finally you have nothing anymore. And that is pretty predictable as happens like that.
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.
So it goes along. It hasn't really completely stopped.
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?
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.
But while you are sitting there, you said, OK, this week we only had one case.
It's really difficult to say that the outbreak has stopped because you can't predict the future.
So it is something that you decide in retrospect. You look back and say, OK, this is must have been the first time stuff.
But I imagine also it must be very difficult,
especially if we're talking about outbreaks that often happen during wars, during breakdowns to get reliable data.
Is it easy to to get data on cases of cholera?
Particularly interesting to see, because it's so stigmatised, it's associated with poverty,
with the absence of safe water supply and sanitation, which nobody wants.
So for a government to admit that they have cholera cases is a bad thing.
And in many countries, particularly in Asia, and governments wouldn't like to admit this,
so they call them watery diarrhoea cases don't report them as cholera.
It's just it's not good for tourism, that's for sure. And it's not good for investment in the country.
So the leadership, the government usually doesn't want to report it.
On the other hand, said if you are in a in a war situation, in a really difficult situation,
like, for example, that was the case in Mozambique, you're starting to bring it up.
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,
indeed, cholera is controlled and and tourism should come back into our country.
So these are two political influences which which which are sitting on you.
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.
But the cases that we find in a setting like this are only the ones which come to us in that
place where there was a cholera treatment centre and everybody living in the province knew.
If you have cholera and you want to survive severe cholera, you have to go to this point.
They won't let you into any other hospital because they don't want contamination in the other hospitals.
You have to come to the cholera treatment centre in the middle of town, which was exclusively dealing with watery diarrhoea cases.
And they have had these books and everybody who came in was written into it.
The next morning, one of our guys would come in the copy, the names, and then entered into the computer.
So we would know every day how many people came into the cholera treatment centre.
But you rightly say so what happens to the people in the future either to come into the cholera
treatment centre or people who don't have enough money to get there or to seek to get them?
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?
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,
which means you get rid of it from the whole planet and people would like to eradicate cholera, which would be a great thing.
But there are people like Taco Bell who found that zooplankton which is in the ocean, can become infected with cholera and carry it.
And once you have an animal host out there,
it becomes really difficult to to think about eradicating it because they will it's very difficult
to imagine a situation that everybody on the boat has a safe water supply and sanitation.
And if some person like this comes in contact with it, it will be there again.
Cholera will get into the human population again. There's no question you can eliminate it from a relatively limited area.
And this improvement of water supply and sanitation, that's the long term strategy, would meet it in Cairo, for example.
And there was a crisis situation that we saw in the first instance. We would like to vaccinate everybody now.
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?
So things have changed a little bit more of an unusual idea 15 years ago.
So you go in there, you tell the whole community, you know what cholera is, you're scared of it.
We are bringing cholera vaccine in here. We're opening these mass vaccination centres and everybody can come in and can get vaccinated.
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.
And you are susceptible again after two months. So basically you gain then two years.
Maybe you should set up a water supply and sanitation. If you don't do this in the two years,
I think it will repeat and your mass vaccination campaigns on approach to selectively or you do something more
permanent and really work on your water supply and sanitation and get that going in the in the time this.
But you have to have communities.
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,
especially in Southeast Asia right now, some of the global programmes for eliminating cholera started, I believe, back in the 1990s.
So how close are we right now in twenty, twenty one to eliminating cholera in these regions?
I think the big spenders in the market have these huge outbreaks.
It was a huge one. And that was thought to be imparted from a person from East Asia working for the United Nations for
the what would you call these troops that they are sending with the United Nations emergency troops?
And they were stationed in Haiti and the sanitation wasn't satisfactory.
So the people there basically had the raw sewage going into a river, which then used this water supply.
And we assume that one or more of these people in the United Nations contingent was infected and transmitted cholera to the local people.
So you can easily transplant something from from one place nowadays with a 12 hour flight to another place.
If sanitation at the other end is not satisfactory, that person comes to New York.
It's very unlikely that it causes an outbreak.
But if that person ends up in Haiti and nobody has taken care of the sanitation properly, then you have another outbreak.
The other that that outbreak is now declined much better control.
The big problem at the moment is Yemen, where, you know, there's a warfare ongoing,
Saudi Arabia and the United States involved and so on, a very complicated situation.
And that wasn't going on. They report a lot of watery diarrhoea and a lot of cholera cases that are still.
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,
you have nothing. And that seems to have happened repeatedly over and over and over again.
So the solution for that is you can do mass vaccination campaigns to the point that there is.
If you have enough time to construct a safe water supply and sanitation, that that is probably the only way to.
To deal with that, to solve that problem, to get control in Yemen over over control,
but nevertheless, I mean, there is there will be another outbreak, I would I would predict.
So the chances of really eradicating it globally are not very high.
But I'm impressed that you're still working on this,
and I wish you very well on your research as you continue to tackle diseases such as cholera and malaria.
Thank you very much for sharing your expertise with us, Lawrence, and thank you all for joining us.
And I hope that you'll join us with some of the other interviews and videos.