All right, so in a video this week, Pete Hudson introduced the concepts of eradication and elimination. So elimination being the the reduction of disease to zero or infection to zero in any, in any specific area. And, and eradication being the global elimination from all areas of any natural infection with, with a pathogenic agent. And many of us can imagine that getting rid of pathogens would be a great thing, right? All of the, these things that make us sick, you know, it, it, it, our lives, in principle, sound like they'd be a lot better if we could get rid of them. So the questions are, what are the challenges to eradication? Why has, why have we only been successful with, at present, eradicating two pathogens, smallpox and rinderpest? [LAUGH] Smallpox and rinderpest. And what are the challenges with setting eradication as a goal and is, are there, are there problems with eradication as a goal? >> Well I think my, Mariah brought one up is that many of these infections are asymptomatic. And to have the reason that you could eradicate smallpox and rinderpest, in theory, is that there's no asymptomatic infections. And so you can identify infected individuals and, and act appropriately. Whatever, culling or vaccination. >> Right, and that's been a challenge in, in many of the, of the targets for eradication. The, the most famous target for eradicate last target for eradication has been polio. All right, which also has a, a, you know, a, a very high degree of asymptomatic infection with somewhere on the order a, of 99% of infections failing to produce observable disease. When that disease happens, it's really terrible and so there's a, there's a real incentive to try and get rid of it. Right? But what that means is that you can have a long period where you don't see any disease, but that doesn't necessarily mean there's no infection, and so you have to maintain this extraordinarily high level of vigilance. Right? In the absence of actually seeing anything that's going wrong. And, and I don't know, one, one of the things that I've always thought is, when that happens, you do see a lot of other things going wrong, going wrong, you think you see a lot of other illnesses, that, that sort of, take, start to take precedence and start to take priority in some sort of a public health agenda, right? So as you get things down to a low level you know, the things that are still remaining also, you know, also take prominence and take up some of that space. >> Don't you think that raises an interesting philosophical, ethical issue too? Once a disease is pretty rare, it could actually be quite low down in the public health priorities for a country. >> Mm. >> Should you keep spending money to squeeze that last bit out, when in fact there are many more significant problems in that country which that money could be using? >> Mm. >> In, in the case of malaria I think it's very interesting that you can go for elimination pretty easily in many parts of the world. >> Mm-hm. >> Should you, take a country like India, should you go for elimination in very large parts of India where there's almost no malaria? >> Yep. >> Or should you put it under control in areas where there's a lot of malaria? >> Right. >> The, it's the same money, same budget. Surely from the body count point of view, the, the human well-being and misery, you should be in control in areas where there's high transmission and it's difficult. >> So setting aside whether we can do that and all those little pockets which are still left to be found and er, disease eradicated from. Recently Bill Gates talked about this eradication of malaria. Hopefully Bill is watching, you know, he may or may not be. >> Hi, Bill. >> [LAUGH]. >> so, so is it useful to have this war against drugs or war against diseases or war against poverty, this sort of strong language that we're going to eradicate something, is that useful? Is that just a really great for a society to rally the troops, or thinking about something which is going to bounce back because of evolutionary pressures? What is, what is our best starting point? Should we be trying to aim for something like 5% of the population affected? >> So I think, I think the jury is still out. >> Yeah. >> On this big question, because we just had two case studies. >> Yeah. >> Where eradication has happened, and I think you know from a big perspective, maybe naively, but eradication seemed like a great idea. You've got a great big scorch. That's being small pox or something that's been, you know, plaguing the humankind for centuries, killing enormous number of people. If you can eradicate it then it's, it would seem like a great thing. But of course it, it only happened when was the last case, 1977? So we don't and with, I think it's been interesting with with smallpox. And I think rinderpest in both cases, it's declared eradicated, we've stopped vaccinating. But, of course, for im, immunity for many of these infections are very, very long lasting. And so, we don't actually current, you know, 1970, 77 is still very recent from a, from a herd immunity point of view. And it is interesting to see now the well some monkeypox is, proc, cropping up in, in West Africa now. And that seems to get, the effective reproductive ratio seems to become closer and closer to one. And we don't actually know if that is because the, the vaccine induced immunity has slowly been waning since I think they, they stopped vaccinating in like late 1980 or something like that. >> [CROSSTALK] Yeah, yeah. >> So, so everybody born since that last vaccine, have obviously [INAUDIBLE] got immunity. And so, so that I think the big really big important question is, if, if and when we eradicate, what do we need to do in terms of thinking about maintaining herd immunity? Do, do we need to, to keep, keep, keep. So with smallpox and rinderpest, we decided okay, the good thing was we would just stop vaccinating. We'd eradicated it. Is that going to be sufficient? That's I think >> Well, you bring up an issue of cross-protective immunity and I think that's really useful to think about because maybe smallpox gives you some cross protection against a different virus. But there's also, from a totally different perspective, a question of whether having immunity to one thing is protecting you against a totally different pathogen, that we don't always understand issues of co-infection and balance. >> Mm-hm. >> And certainly with herpes virus there's been several published examples, not in humans but in animal models. Where we see the presence of, for instance, a gama herpes virus can confer immunity to a bacteria or to something completely different. And so that's another level, even beyond thinking about smallpox and monkeypox, we have to begin thinking even more broadly. If we got rid of polio, or we get rid of, you know if you could totally erase Ebola. Now, are we in 20 years going to be having a worse effect when some new version of lassa fever comes out or something else that we're just not thinking of right now that's totally different, that some level of immunity to a current pathogen is being helpful for? >> Hm.
