[Music] Dusty's really great quote from Peter Medova was a British biologist who once said that the virus is a piece of bad news wrapped up in protein. And that describes viruses very well. [Music] Birological with Florian Kramer. [Music] Hello and welcome to episode zero of Birological. This episode was recorded on January 4 in New York City. My name is Florian Kramer. I'm a professor at the Department of Microbiology at the Eiken School of Medicine at Mount Sina in New York. And I'm also the director of the Ludwig Boardsman Institute for Science, Outreach and Pandemic Preparedness at the Medical University of Vienna in Austria. And also the director of the Ingez Semervais Institute for Infection Research, which is also located in Austria. Because of recent developments, including the pandemic, I thought it might be a good idea to start a podcast that provides some general and basic information about viruses, but also about vaccines, about immunity, and the ideas to record short episodes, maybe 15 minutes, to cover different viruses every week. I would like to cover viruses that are medically relevant, but I also would like to spread some virus trivia and to cover current events, for example, if an outbreak happens, or if you have a strong flu season like this year. But with this episode zero, I will provide some basics about viruses in birology in general, and that may take a little longer than 15 minutes. And maybe we will also have some future episodes that are longer that cover immunity, vaccine development, or similar general topics. But again, today I'm going to start with some basic things about viruses. So the first question is what are viruses? Viruses are a combination of genetic information that codes for protein and that protein, or several of them encapsulate the nuclear acid that has this genetic information. Often, but not always, viruses also include a lipid layer for protection, but it can just be protein on the outside. And that's the basic building plan of a virus. Of course, this can get much more complicated, but in general, just nuclear acid and protein, those are the most simple viruses. Viruses are very small, usually between 80 to 120 nanometers in diameter, but there's a lot of variation there, and we'll talk a little bit more about very small and very large viruses later. But just to make a comparison in terms of size, a human here is about 80,000 to 100,000 nanometers in diameter. So viruses in comparison are really very small and they're basically invisible, even in a microscope. You can only see them and visualize them within electron microscope. As I mentioned, viruses are usually a combination of genetic material and protein and maybe lipids. And there's this really great quote from Peter Medovar, who was a British biologist, who once said that the virus is a piece of bad news wrapped up in protein. Although I have to say that it can be bad news, but it doesn't have to be, not all viruses are bad, some are actually beneficial and I'll give you some examples later. Viruses were discovered in the end of the 19th century. The first virus that was discovered and described was the Bacchumosaic virus or DMV. Back then it was known already that bacteria could cause infections and disease, but it was also known that they could be removed from liquids via filtration. And the discovery of the Bacchumosaic virus goes back to Dimitri Ivanovsky, who was working on diseases of the Bacchumlands on Crimea. And so he mashed up leaves from disease, the Bacchumlands and then filtered that liquid through porcelain filter and then he put the filtered liquid back onto the Bacchumlands. And they got the disease again, even though the material was filtered and that made it clear to him that the disease he was observing wasn't really caused by bacteria, but by something smaller. And these experiments were repeated a few years later and reproduced by a Martinez Bajorink in the Netherlands. And he basically could show the same that he could filter these mashed up leaves, they choose from these mashed up leaves and still best disease on to new plants with this filtered material. And so he concluded that the battle chain that caused the disease has to be very small and he called the battle chain virus or filterable virus. And virus is a lead in term which basically just means slime or juice or poison and that was basically the beginning of modern virology as a science. Now viruses are not living beings, they're not alive at all. Of course one could argue about that and I think virologists would like to see them as living beings, but they do not fulfill all criteria of life. So first they don't have a metabolism and second they cannot proliferate on their own. They always need a host organism, basically a living organism which they can use for proliferation. So in a way they are the perfect parasite. And this is very different from bacteria which can also cause disease of course, but they don't necessarily need a host. You can grow them in a nutrient rich broth, but that doesn't work with viruses. They really need a living cell, a living organism to proliferate. If you would just put them into a nutrient rich broth or sugar solution, nothing would happen. The viruses basically wouldn't proliferate the need a living cell. Depending on the virus, the living cells may be quite different. So some viruses infect bacteria, some viruses infect archaea, some viruses infect fungi, some infect plants, and then there's plenty of viruses that infect animals, all kinds of different animals, unfortunately including humans. And the idea is that for every species on this planet, for every species of living being, there are at least 10 different viruses that are specific for that species. And that means that there are a lot of different viruses out there, and most of them are actually completely harmless for humans. And there is currently a large effort on going in virulgy to discover and identify all these viruses and map their diversity to get a better idea of how many they are actually out there and which ones we have to be careful about. So viruses can be divided into different groups, usually according to what we call the Baltimore classification, where viruses are classified according to their genome and the properties of their genome. So this classification was introduced by David Baltimore, a virologist who I believe got the Nobel Prize in 1975 for his work on retroviruses and viruses that can cause cancer. Unfortunately, he passed away in 2025. He was also really a good fly fisherman, but basically he came up with this classification scheme and that classifies viruses according to what their genome is made of. I don't want to go into too much detail here, but there are viruses that have a DNA genome which can be either single stranded or double stranded. So humans also have a DNA genome. These viruses have genome that's made of the same material. Then there are viruses that have an RNA genome. Again, this can also be single stranded or double stranded. And then there are super interesting viruses that have an RNA genome, which they transform into a DNA genome in the host cell and they are called retroviruses and HIV is one of one such a retro virus. Once we talk about the different viruses in the different episodes, they will always specify what type of genetic information the specific virus has. Viruses also come in different shapes and sizes. There are some very small viruses that are just about 40 nanometers in size or even smaller. There are also very large viruses. That's a set to come in very different shapes. A very common and simple shape is basically a virus where the genome is packaged into spherical protein shell, which we typically call an anvilope. And many cases this protein shell has a symmetrical and regular order, almost like a volleyball or a soccer ball. An example for this are becordana viruses, like bolio viruses or rhino viruses, they're pretty small, they're round and they have a symmetric regular order. Then there are other viruses which are also spherical but less symmetrical. An example for that are or the mix of viruses like influenza virus. And they can be spherical but maybe also a little bit X-shaped, sometimes a little bit elongated, sometimes they're a little bit smaller, sometimes they're a little bit bigger so they're not really regular in size and we call this plymorphic. Then there are viruses.
that are filamentous, so really elongated, almost like a worm, and they are called phyloviruses and Ebola viruses in an example for a phylovirus. They still have a very small diameter, but can be 1 to 2 micrometers long, so this is 1000 to 2000 nanometers long, so they are much longer than their thickness in diameter. Viruses then infect bacteria, for example, which we call bacteria "fages", because they eat bacteria, may look like a little moonlander with a head and then some legs, and they really use these legs to attach to the bacteria, and in fact the bacteria, so that's a very interesting shape. Then there are viruses like Robtoviruses that are bullet shaped, and one example is the rabies virus, which also has this bullet shape, and in this case it really fits because of course rabies is a very dangerous virus. What has to be said in general is that not all viruses are problematic, or cause issues, most viruses are actually harmless for humans, and as I mentioned earlier there are even viruses that are beneficial to us. It is important to understand that we have co-evolved with a lot of different viruses, and specifically retroviruses have during our evolution, not just as humans, but even before that as mammals deposited their genome into our genome, and they're not part of our genome. There's a lot of retroviral sequences in our genome, and most of them are not even forming infectious particles anymore. Many of them don't do much, they just tag along as part of our genome when we reproduce. One of these viruses, which ended up in mammalian genomes a long time ago, actually carried a gene for a protein that's called syncedidine. That protein is essential for the formation of the placenta. We basically did the other way around. We hijacked the virus in that case, and there would be no mammals without this virus, because if you wouldn't have that sequence, there would be no placenta, and that would mean there would be no mammals. It's not always the case that only the virus, profits or benefits from the infection. In this case, it was basically the host, us, who profited from the integration event. Viruses can also be used for all kinds of other things. In biotechnology, for example, for the production of recombinant proteins, for gene therapy, but also in agriculture or forestry as an organic bestie site. Backola viruses are one example here. These are large DNA viruses that are completely harmless for humans. They infect and kill moths, and they're used to control apple worms, for example, or insects that damage forests. So there's a lot of different uses for viruses. Also there are more and more bacterial infections with multi-resistant bacteria that are really hard to treat, and because this bacteria resistant to most of the antibiotics that we have at hand. This can, in many cases, end deadly. One new approach to fight these infections now to use bacteria-fages. So viruses that infect and kill bacteria. That's a big development, and the interesting development recently, to basically have bacteria-fages, viruses that infect bacteria to treat these bacteria-infactions. It's a very promising approach that becomes more and more important since we have more and more bacterial resistance, and this is on the rise, so that's an important use for viruses. Finally, viruses are also used to treat cancer, and kill cancer, so specifically there's one such virus on the market in the United States, but there's also many different viruses in development as on-cullidic cancer therapies. So in conclusion, viruses are not always the bad guys, but of course very often they can cause disease in humans or domesticated animals in the bite life. And as I mentioned, viruses always need cells to proliferate, and I would like to describe the typical life cycle of a virus when it starts to attach to a host cell and then replicates and then gets released from that host cell. So first the virus has to attach to the cell, and in order to infect it, and that usually happens via the surface proteins of the virus, which typically bind or attach to specific structures on the cell surface of the host cell. And depending on the cell and the virus and the species, the structures that we call receptors can be vastly different. So often they are sugar structures on the cell surface where their proteins can be very different proteins. One example that is now widely known is SARS-Coronavirus II, that has a spike protein on the surface, and with the spike protein it binds to protein on our cell surface, that's called ACE II or an angiotensin converting enzyme II. It's basically the receptors, the virus comes in with its spike protein, it attaches to that protein on the cell surface, and that's how it attaches to our cells. So the virus attaches to the cell surface, and then in the next step the virus has to make it into the cell, and there are multiple ways to achieve that as well. More precisely, more specifically, it's not the virus that has to make it into the cell. It's the genome of the virus, it's genomic information that has to make it into the cell. And as I said, there are multiple ways for viruses to do that, but especially for viruses that infect human cells or animal cells, the cell often does this job for the virus and actively takes it up by a little vesicles that we call endosomes. So again, the virus starts the infection by binding to the cell surface, and then the cell membrane forms an indentation and a small vesicle forms around the virus and the cell actively takes it up. So it's the cell itself that does this, unfortunately. And these vesicles then travel inside the cell, they mature, typically there are pH changes to turn acidic, and in many cases that then causes changes in the virus structure. What then often happens is the virus membrane, so basically the protein and the lipid on the surface, fuses emerges with the vesicle membrane. And then basically the inside of the virus is emptied out into the cell, and that's where the genome was, right, inside the virus. Now the genome that was inside the virus is all of a sudden inside the cell, and that's of course a problem. So there's other pathways how the virus can get into the cell as well, but this one is very common. So as soon as the viral genome is in the cell we have a problem. The cellulam machinery recognizes the genome and it starts to read it and it starts to make viral proteins. And so these new viral proteins then also amplify the viral genome and you get more and more genome and more and more viral proteins. And then new viruses are formed which then usually leave the cell via the cellulam membrane, which is a process that is called viral budding. But there are also other mechanisms for leaving the cell. In some cases the cell just bursts and the new viruses are released. That's very common for viruses that infect bacteria for example, but there's also multiple other pathways for the virus to exit the cell. So in principle the virus high checks the cell, takes over control and transforms the cells, the cell into a virus factory. And that is bad of course because that means a lot of viruses are produced, a lot of new viruses are produced that then go on and infect more cells and the infection continues in our body. That is often what happens but that's not always the case. There are also some viruses that infect the cell and then hide in it often for a very long time. That can lead to persistent or chronic infections and there are a number of ways how viruses can achieve that. The other best viruses are good examples for that. They're really good at this, they enter a cell and then they deposit their DNA genome in the cell nucleus. So it's not becoming part of our genome but it's sitting right there next to our genome, next to our chromosomes and it kind of forms a little extra chromosome. Basically a mini chromosome that's just sitting there for years in the nucleus of the cell. And then this can get reactivated, the virus can get reactivated. For example if we have a lot of stress and then the virus replication starts again and then you get a full blown infection. Retroviruses are similar, they have a similar mechanism but it's a little bit more complicated. So they are RNA viruses and when they enter a cell they transform their genome into DNA and then insert it directly into our genome. So that information that viral genome really becomes part of our genome. But this of course can have terrible consequences as we see with HIV which is one of the viruses that can do that. Some of these persistent or chronic infections can also lead to cancer. The human papilloma virus or HPV is such an example.
virus infection, chronic virus infection, persistent virus infection in the end leads to the development of cancer. Another example is the hepatitis B virus that can also basically cause chronic infections that then lead to liver cancer. So just because a virus doesn't abuse the cell right away, as virus factory doesn't mean that it's harmless. And there can be negative consequences in the long run. But for acute virus infections, the virus enters, it takes control, and then, as I explained earlier, forces the cell to make more virus, with the consequence that the cell dies in the end usually. Either because all the resources are used up or because the cell sends the virus and committed suicide, and there's a number of ways for cells to do that. They have innate immune sensors that are able to specifically detect bits and pieces of viruses. And of course, such a cellular suicide stops viral reproduction. If the cell is dead, the cell can make more virus. And that in a way is helpful if the cell recognizes early enough that it is infected. And then of course, there's another possibility, and that is that an immune cell recognizes that the cell is infected and just kills it off. And this mechanism of course also helps to slow down and resolve infections. So just to take a step back, cells are infected, the virus replicates and spreads in the body. And then in the end, the host either dies from the infection or the host recovers. And that's actually much more likely in most cases. But that means either way that this would be a dead end for the virus. Because if the host is dead, that also means the virus can replicate anymore. Or if the host recovers, that means the virus infection is also over. And in order to survive, the virus has to infect the next host, the next person, right? It has to spread. And there are many ways to achieve that. There are many infection and transmission routes that exist that viruses use. And it's very important to point out these differences because the various transmission routes or infection routes make some viruses much more dangerous than others, especially in terms of pandemics. Some viruses can easily be stopped from spreading. Well, for others, it can be super difficult. And that often depends on the transmission routes. So viruses that infect the airways, the respiratory system are often transmitted by respiratory droplets in the aerosols. And those are hard to stop. Just to specify this a little bit, droplets mean larger liquid particles that do not stay in the air for a long time. While aerosols are very tiny liquid particles that can stay in the air for a very long time. Droplets are typically produced when people sneeze or they cough or they talk very loudly or they sing, but aerosols can be produced by just breathing. And if there are viruses in these droplets or aerosols and these droplets or aerosols are inhaled by someone else or they simply land on some of these mucosa surfaces, then the person may get infected. And this spread where the respiratory tract is really hard to stop. That can only be done with masks, like N95 masks, for example. And especially when a virus spreads where these tiny aerosols, it's very hard to stop. With droplets, it's a little bit easier. And so this is transmission route, an infection route that's problematic in terms of new outbreaks and pandemics. It is also possible to get infected via objects. For example, if somebody's infected with a certain virus and touches a cell phone, the virus then lands on the cell phone, then somebody else touches the cell phone. Now that person has the virus on his or her hands and then touches the eyes or the mouth, the face somewhere, then the virus can infect that person too. And we call that transmission via foamites. In this case, foamites basically just mean objects or transmission via objects. Then there's viruses that are transmitted via direct contact between two people or via bodily fluids. There can be transmission via vectors. What is meant by that is viruses that are transmitted via mosquitoes or ticks that bite individuals and and transmit viruses like that. We've also in the past seen transmission of viruses via blood products and donated blood. So there are really many different ways of how viruses can be transmitted. And it's usually specific to that virus. But especially if you talk about viruses with pandemic potential, we're mostly concerned about viruses that spread via the respiratory tract because they're so hard to stop. We often hear about outbreaks with super deadly viruses in the media like Ebola, for example, or Mahabur virus. And people are really afraid of these viruses and worry that there would be a pandemic with Ebola virus or Mahabur virus. Again, because these viruses are so deadly, they have a very high fatality rate. Basically, they kill most people that are infected with them. But they typically spread via direct contact and via bodily fluids. And it's very unlikely that the virus like Ebola will ever cause a pandemic because in the end, it's very easy to stop just by using barriers like gulfs and by using basic hygiene. And so maybe we shouldn't worry too much about these super deadly viruses, except of course, in the case where we had close contact with the virus or with somebody who was infected with the virus. On the other side, we have something like SARS-CoV-2, which actually can be transmitted via aero-source. And that is a virus that is really, really hard to stop. So this is an example of a virus that is a respiratory virus that is transmitted via these tiny aerosols and very, really need to use specific, very good masks like N95 masks to stop the spread of the virus. So those are viruses that I would be really concerned about when it comes to the pandemic. So these transmission routes are really important and allow us to assess how easily an outbreak can be stopped to a certain degree. There are a few more epidemiological terms that I would like to explain. One of these terms is that they are not or basic reproductive number. This number tells us to how many people an infected person will pass on the infection. It basically tells us how fast the virus will spread and how easy an outbreak can be stopped. One virus that is extremely infectious, just to give you an example here, is the measles virus. Missles virus has an R0 of 11 to 18. So that means on average, one measles infected person infects 11 to 18 other people if they are not vaccinated, if they don't have immunity. And that's a large number of people and that's why measles is actually so hard to stop. And that's why we have such a big issue right now with measles outbreaks. Influencer, so seasonal influenza on the other side has a relatively low R0. It's only about 1.5. So reproductive number of about 1.5, which means that it's much easier to stop. And that also explains why there was so little influenza circulation during the COVID-19 pandemic because of all the travel restrictions and the masking and the social distancing. And that had really a huge impact on influenza transmission. And there are not a reproductive number of influenza is lower, much lower than that for SARS-CoV-2. So it was harder to stop SARS-CoV-2. But as I said, there was a huge impact on influenza transmission during the pandemic. So there are not this also pretty important and provides an idea of how easily a virus can be stopped. Also, if there are not this below one, the virus will disappear by itself and then outbreak will just end by itself. Because if one infected person infects less than one person, there are few and fewer infections over time and the virus will just disappear. Then there are the terms case fatality rate and infection fatality rate. So case fatality rate is the number of deaths per number of detected infections. So if I have 100 infected people and 50 of them die, I have a case fatality rate of 50%. And that's also super important number, especially when there is an outbreak within new virus because it tells us how severe the infections are and how big the problem is. The issue is the case fatality rate is that it's based on detected cases. But many viruses also cause asymptomatic infections or milder infections that might not be diagnosed because maybe not enough PCRs are available, not enough tests are available. And this was the case in the beginning with SARS-CoV-2, for example. And so it might be hard to figure out the actual number of infections. However, this can be done via serology studies. To basically look at how many people developed antibodies to the virus and that also captures asymptomatic cases or cases that were not diagnosed. And if we do that with that data, we can calculate what we call the infection fatality rate. And that's the number of deaths in relation to the true number of infections.
And for many viruses, because there is asymptomatic infections and mild undetected infections, the infection fatality rate is often much lower than the case fatality rate. Another important term is the incubation time. That's the time from between the exposure when the actual infection starts to the time when the first symptoms occur. And this time interval can be pretty long. So for rabies, for example, this can take weeks or months. And with other viruses, this can be pretty short. For example, in flants of viruses, for inflants of viruses, the incubation time is about 24 to 48 hours. So in one case, weeks to month, and in another case, just a few hours, right? And when we stink about the incubation time, we also have to keep in mind that in some cases, people can already pass on the virus during that incubation time. That's, for example, the case with SARS-CoV-2. And that means that people can spread the virus already before they even know that they are sick. And that makes it much easier for the virus to spread, right? If you can only spread the virus and pass on the virus once you're sick, it's much easier to stop because once you're sick, you know that you're sick. You might self-isolate. And then you might not infect anybody, right? But if you don't know that you're sick, then that is much harder to do. And unfortunately, as I said, that's the case with SARS-CoV-2. There are a few more germs that are used often and that I would like to explain. One term is emerging viruses. What does that mean? That means viruses that did not cause issues in the past, but that are starting to cause issues and start to cause trouble. Then we also have the term of re-emerging viruses. Those are viruses that we had on the control in the past, but we are now losing control over them again. And measles viruses, one such example. If you go back a little bit in history, in North America and in Europe, they were not really an issue, but now we have relatively large outbreaks again. And that important term is so Nordic infection and so Nordic viruses. What is meant here are viruses that usually circulate in animals, but then jump over the species barrier and start to infect humans. So basically a virus is transmitted from an animal to a human in this case. And that's important because this is how almost all of the pandemic started. Then there is the term epidemic, which means a large outbreak that is restricted to a certain population or to a certain area. And then we have the term pandemic, which means the infection of a large number of people across a large geographic area, often globally. It doesn't have to be globally, but usually a very large geographical area is involved often more than one continent. So those are a few of the important definitions that people should have heard of. Now I also wanted to say a little bit about outbreaks and pandemics. The reality is outbreaks with new viruses have monoregular bases. If you look back at the last 30 years, we had countless outbreaks, which also got media attention with outbreaks in the emergence of the handra virus, deeper virus, different even influenza virus strains, SARS-Coronavirus 1 in 2003. Ebola showed up on a regular basis. We had a C-curvirus outbreak. We had yellow fever. We had hunter viruses. We had lots of fever, and bugs more recently. Also, Bolio came back even in New York City a few years ago, Marburg virus, and so on and so forth. These things happen constantly, basically. But most of these outbreaks actually don't have larger consequences. Of course, people who are infected in these outbreaks, for them that's terrible. And of course, also people who are close to the outbreak area can be affected. But most of these outbreaks do not lead to pandemics. They are not the problem for the global population. The two pandemics that occurred in the last 30 years, were the H1N1 influenza pandemic in 2009. So there was swine flu, and the COVID-19 pandemic of 2019 and 2020. But compared to the rate of outbreaks, that's actually not a lot of pandemics, right? Because there's a lot of these outbreaks, and most of them don't seem to have larger consequences. If people are interested in all of these outbreaks, you can register for a mail server that's called "Bromat Mail". I'll provide the link here in the description for the podcast. And if you sign up there, you can get frequent updates on what actually happens in real time with reports from doctors and scientists around the globe about outbreaks and specifically sonotic infections. You may get nightmares from reading these events, but it also shows that most of these outbreaks are inconsequential for the global population. If you look back at the last approximately 100 years, we had six pandemics, which sounds little when considering these numerous outbreaks that we see all the time. We had an H1N1 influenza pandemic in 1918 that was also called Spanish flu, and that had a huge impact. It killed between 20 to 100 million people, depending on the studies, the estimates. We had another influenza pandemic in 1957 with the H2N2 subtype with about 2 to 3 million deaths. Then another influenza pandemic in 1968, in this case with the H3N2 subtype and also about 2 to 3 million deaths. Then in 1981, 1982, the HIV pandemic started, and that's still ongoing, with about 42 million deaths so far. In 2009, we had another influenza pandemic, which was caused by the H1N1 subtype and swine flu strain, and that caused about 250,000 to 300,000 deaths. And then of course, we had the 2019, 2020 COVID-19 pandemic that was caused by SARS-CoV-N2. And here the official death count is around 7 million, but estimates based on excess mortality point to around 30 million deaths, so that's not a small number. Where are these viruses coming from that caused these pandemics? Here we have to come back to these sonotic infections. In principle, all these viruses come from animals and started to infect humans at some point. And this was the case for all the four influenza pandemics in the last approximately 100 years. This was the case for HIV, and it was very likely also the case for SARS-CoV-N2 in COVID-19. Of course, we already have a lot of viruses that circulate in humans, and that cause a lot of issues, like measles virus, for example, or different herpes viruses, or rhino viruses and so on and so forth. Again, many of these actually cause huge issues, but the problem is if a new virus chumps into humans from animals, there's a big difference here. And the difference is that there is no immunity against these new viruses in the human population because the virus hasn't circulated in humans before. And so if a new virus chumps, there's no immunity, and that allows the virus to really burn through the human population, and that's basically causing a pandemic. And this is in contrast to viruses that already circulate, were a large proportion of the human population actually has immunity to certainly extent. And there are also often vaccines available against these viruses that already circulate in humans that can provide protection. So these sonotic infections are really the big problem in terms of pandemics. So if you look at the number of these reported outbreaks with sonotic viruses, we see that they are increasing, and there are several different reasons for that. So the first reason is a relatively trivial one. Of course, we're now much better in detecting and diagnosing new infections. If you go back 50 or 70 years, and there was an infection with a new virus, let's say in rural Nigeria, and the outbreak didn't really spread, there may have been some reports about this, and this might have been called a tropical fever, and probably there was not much of an investigation, and usually nobody found out, but what actually caused it. So it wouldn't be reported in a way that this is a new outbreak with a new virus. Nowadays, it's much easier to identify these things, and the media would report it, and this is likely one of the reasons why we hear more about these outbreaks. On the other side, there is likely also a real increase in sonotic infections and outbreaks. There are more and more people on this planet, and with an increase in the population size, the chances of somebody getting infected with a sonotic virus increases as well. Also, more people means we need more livestock to produce more food, and that means that the interface between humans and animals increases, and that leads to a higher risk as well. So more people and more livestock, more animals means that there's a bigger interface, and the bigger the interface between humans and animals is, the higher is the chance of a virus jumping and causing an outbreak. Another point is risks through climate change.
This mostly has to do with vectors, so mosquitoes and ticks that spread disease and spread virus infections. Many of them need warmer climate to survive, and because of climate change, some species, like for example the Asian tiger mosquito, increase their range into temperate climates, that happens in Europe, that happens in North America, and they bring viruses with them, viruses like dengue or chikungunya virus, which previously have not been an issue in these regions. Another example here is the Hioloma tick, that's a tick species that typically is found in warmer climates, but now spreads north in Eurasia, and that tick can carry the Crimean Congo-Hemeragic fever virus, and basically climate change is expanding the range of this tick, and with the tick, it's also expanding the range of the virus. Climate change can of course also lead to changes in human behavior, and maybe microbes can survive better in certain areas when the climate changes, and it's not completely yet, which other surprises climate change will bring in terms of infectious diseases. That's something that really needs to be monitored, and I hope you are not in for too many bad surprises there. Another problematic point is destruction of natural habitats. Just as an example, if you have a potentially problematic virus, that only exists deep in the rainforest in the Amazon region, where nobody ever comes in contact with the virus, it's actually not an issue, right? Because if nobody gets infected, there is no problem. But if the forest is cut down to produce farmland, and people settle there, then all of a sudden there might be contact between humans and the virus, and that could of course create an issue. The final problem of the final issue that might lead to more of these infections, or at least to spread of these infections, is the interconnectivity of the world, of the modern world. If you go back 100 or 150 years, it wasn't so easy for a virus to cross the Atlantic, for example, right? That would have been by ship, that took a long time, a week or longer, and with some luck, the virus would have burned itself out on the ship before the ship actually arrived the other side of the Atlantic. And day, that's a very different story. With air travel, you can get from any place aid, to any place beyond this planet within 24 hours. So just as an example, you can get infected in Mongolia with a new virus, and be in New York City before you even get sick. And that makes it also much harder to stop these outbreaks from going jubilant becoming a pandemic. So this connectivity combined with an increased risk of sonotic infections, of course, increases the risk for future pandemics. I believe you need to be prepared for that, and we will certainly talk more in future episodes about pandemic preparedness. We will also talk about different types of viruses, we'll talk about specific risks, but I think that was it for today, with an introduction about virology, epidemiology, outbreaks and pandemics. As mentioned, we'll try to get one episode online every week in the future, usually shorter than the one today, maybe around 15 minutes. But we may also have some longer ones about immunity and vaccines, for example. If you have any comments or questions or suggestions, please write an email to
[email protected]. Just to explain the name a little bit, I know this is a little bit hard to understand, but a podcast viacstad basically is the producing company that does this with me. And viacstad translates into workshop in German. And so these are the guys who helped me to produce the podcast and that's the email address. I'll also put the email address into the notes, so that's easier to understand. A
[email protected]. We'll likely also have Q&A episodes every now and then, so if people sending questions can actually address them, talk about the questions. And I will also try to add sources and links to the literature for each episode in the comments section. So thanks for listening in and until next week, bye! If you're enjoying the podcast and would like to support our work, visit us on Steady. You'll find the link in the show notes. And don't forget to follow and leave a review on your favorite podcast app. [Music] Podcast viacstad.
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