Plagues and Peoples

"Other than Camus, this is one of the first books I read, as I was trying to understand where HIV came from, why it was spreading and what might happen if it spread worldwide. How did people respond historically to other epidemics? In describing why epidemics happen, McNeill emphasises ecology—community, sociology, travel, climate—and how this affects the spread of different infectious agents. It seems logical that the spread of infectious agents would not only depend on their infectivity but also the environment where the infectious agent first exerts its influence. He comes to the conclusion that these epidemics happen primarily because of ecological influences. McNeill wrote the original edition before HIV was discovered and I don’t think he modified the book a lot in the second edition, in which he talked about the HIV epidemic. When he addresses some of the influences that resulted in the spread of HIV, I don’t think he emphasises the influence of behaviour enough, although he does mention it. He looks upon HIV as originating from changes in ecology, that the virus could have been a recombination—which could be true—two viruses that recombine to finally become HIV. That’s one of the theories. In fact it is a worrisome theory because it would mean the HIV might recombine or mutate again to become an even more contagious or lethal virus. “McNeill’s is a worrisome theory because it could mean HIV might recombine or mutate again” Where the emergence and spread of HIV fits with McNeill’s theories is that it is felt that the virus originated in monkeys and spread to bush hunters in areas of Western Africa. As the bush hunters travelled and went back to their villages, they spread the new virus through sexual intercourse. They had acquired, it in all likelihood, through accidental inoculations as they used machetes to kill and skin animals. The change in ecology would be the transfer of the virus from monkeys to humans followed by the ability to move from forest village to multiple villages and eventually internationally, the virus spreading by human sexual intercourse rather than by monkeys. His book is instructive because it goes so far back. He’s done a lot of research and it really says, in a different way, that these plagues are going to be with us because the world is changing. You’ve got globalisation—so now we have travel not by horseback or by military people in war but we’ve got airplanes where people travel and can spread new infectious agents. And we have massive populations of migrating people such as in the current refuge crises where an infections agent may be carried into a susceptible population with migration. Then he goes into many of the issues that Laurie Garrett points out. Looking at all of this historically, what are the things that we have to worry about? The issue of drug resistance for example. WHO has recently provided a list of over 20 bacteria that are a threat to global health because we either lack appropriate antibiotics or there is antibiotic resistance. The virus that he highlights in his book is the influenza virus: the big epidemic in 1918 that killed more than 20 million people in two years. We have not seen an influenza virus epidemic that large again but we do know that each year we have to deal with how the virus mutated and whether or not the vaccine that was developed for that year will be effective or whether a new mutation will occur for which we don’t have a vaccine. McNeill also goes into what has been attempted repeatedly but has fortunately never been successful on a large-scale―the use of infectious agents for biological warfare. That is still something people are talking about and there have been attempts to use it. In his book, McNeill doesn’t mention the use of HIV as a war weapon, but it has happened. Women in rebel-held areas of Africa have been deliberately raped by HIV-infected men who know they will leave behind a virus that will eventually, without treatment, kill the woman, perhaps infect male sexual partners and also infect future infants should she become pregnant What these rebels leave behind is the equivalent of a viral landmine. It’s a form of trying to immobilise the opposition long after rebel activity has ceased. There is documentation that this was included in the Rwandan massacre in 1994. McNeill’s book is looking back at history and asking what we can learn from it. And, in my opinion, what we learn is that we’ve got to relearn what has happened before―that infectious disease epidemics may disappear but reappear in a different guise and may be as threatening today as they were 100 or even 500 years ago."

"I had long known of McNeill’s work as a world historian. In Plagues and Peoples , he showed that humans were not only vulnerable to a force of nature – disease – but that their actions and ways of life made them more so. He looks at how diseases became much more prevalent, how they spread widely. In Roman and Greek times, diseases were transported with people as they moved from one place to another. A key moment in the history of mankind is the spread of diseases across Eurasia during the Middle Ages. For me, perhaps the most important example of the spread with human interaction is the diseases that the conquistadores brought with them from Europe to Mexico. Many of the people of the Americas were wiped out by those diseases. In short, this book opened my eyes to the relationship between humans and the rest of nature. Most history books deal with interactions amongst humans, with a passing mention of the weather or the oceans, which are seen as barriers to human interaction. What this book does is bring the role of natural forces – not just diseases – to the forefront and show how, despite what we think of ourselves, we really are a part of nature and vulnerable to the forces of nature. At the same time, we are not just passive victims of natural forces but we have greatly influenced these forces, as in the case of diseases. We are the ones who spread diseases which were once local to the rest of the world. I think that diseases and natural forces are an essential part of understanding world history. And that is what turned me from a political and social historian into an historian of technology and the environment."

"Yes indeed. It’s an absolutely wonderful book. It’s thought provoking, beautifully written, and has stood the test of time – more so than the book we’ve just been discussing. McNeill is an academic historian, and he updated the book when HIV came along, so it’s reasonably up to date. It highlights human interactions as important milestones in history. The one that really caught my imagination was the European invasion of the Americas. I was fascinated by events that began in 1492, when Columbus arrived in America. At that point, the Americas had been isolated for around 14,000 years. The first humans arrived in America over a land bridge between Siberia and Alaska. But that land bridge disappeared as the sea level rose after the Ice Age; it became flooded by what is now the Bering Strait. So, these Native Americans were isolated from other human contact until the arrival of Columbus. Thereafter Europeans poured into the Americas looking for commercial opportunities – from growing sugar cane to plundering gold. Of course, the Europeans brought with them loads of infectious diseases – all the childhood infections, measles, mumps, rubella and, most notably, smallpox – all of which native Americans had not experienced. So this human interaction was disastrous for them. “Cortés and his band unwittingly infected the Aztecs with smallpox, and masses of them were ill and dying by the time he conquered them” Cortés fought and conquered the Aztecs in 1521, and his victory was greatly aided by smallpox: he and his band unwittingly infected the Aztecs with smallpox, and masses of them were ill and dying by the time he conquered them. Similarly, the Incas were virtually wiped out by the disease. These are the events that you don’t find in the history books. It’s mind blowing, really, that a whole population could be decimated like that. But they’d never met these diseases, so they didn’t have any immunity. Neither did they have the in-built genetic resistance that Europeans had generated by centuries of exposure to the microbes. In his book, McNeill says that the Native American population dropped from 30 million to 3 million within 50 years of Cortés arriving. Just absolutely devastating. Until McNeill’s book was published, people very much underestimated the power of microbes . I mean, maybe Cortés and Pizarro would have conquered the Native American populations anyway, but at least they wouldn’t have been almost totally wiped out, as they appear to have been. So yes, I love that book. It’s brilliant. And my own book, Deadly Companions , is a similar historical account, but much more from the point of view of the microbes. I don’t think it has changed much since he updated the book, to be honest. If anything, the threat has worsened, because of what Laurie Garrett was saying: our population has totally exploded. Any crowded urban situation is absolutely ideal for viruses to jump from person to person. The incidence of emerging infections has increased over the years and is still increasing. We can expect around one a year now. Most of them are not going to go global like SARS-CoV-2, but they are there, and yes, they’re getting worse. We do have a few antiviral compounds which work, particularly against HIV, but generally only against one type of virus. That’s the problem. We don’t have anything for viruses like penicillin, that is active against many different types of bacteria. So we generally have to rely on vaccines to prevent rather than cure virus infections. And again, it’s the short term planning that’s the problem. For example, scientists had made a prototype vaccine against Ebola before the 2014-16 outbreak, but commercial companies were not interested in manufacturing it because not enough people get infected with Ebola virus to make it worth their while. Academic units had gone as far as they could with the prototype vaccine, but when Ebola appeared again in 2014 it wasn’t ready for use in the field."