This week I was speaking to a client and she said to me that she was so relieved that the COVID-19 restrictions were lifting and that things could get back to normal. And she went on to say that, especially with COVID-19, really this was just a once in a hundred-year problem and that she couldn't wait until life went back to normal. And I started thinking to myself, is what she's thinking and saying actually true? And I know that through history, diseases and infections have been periodic and have caused massive problems. And so this week I wanted to focus on a range of different pathogens, bacterial, viral, and also yeast and fungal pathogens as well.
And so today, we're going to be talking about what you should know about pathogens for 2021. And I think that this is particularly important because certainly this year, like no other, it is firmly focused, and for all of us, we've all been affected by SARS-CoV-2 and the impact that this virus is having across the planet. And we've all learned about various aspects of infection control. And whether we have personally adopted these or not, we are aware that they are being applied worldwide to a greater or lesser extent. And so a lot of these practices such as, for example, instead of shaking hands, touching elbows, or washing our hands more frequently, or maybe adopting mask-wearing to minimize our coming into contact with aerosols. All of these are infection control procedures and practices aimed at reducing harm or harm minimization.
But I need to focus on some principles of what a pathogen is because a lot of you might be confused and it is my role as a health communicator to talk to you about what exactly a pathogen is. So we're going to jump straight into this now, and then we're going to end by focusing on a lot of the infection control practices that you should consider adopting and taking advantage of when it is necessary. And we're also going to have a quick trip through history to focus on some of the major pathogen epidemics that have affected humankind throughout history.
But if we define a pathogen as an organism that causes disease to its host, this can be a bacterium, a virus, a yeast, or a fungal cell. And we need to understand that pathogens occupy absolutely every environment across the planet. And they are found in hostile environments growing quite happily on, for example, nuclear waste and even rocks which are found thousands of kilometers beneath the surface. To put this in context, because I really do like word pictures, if you take a liter of seawater, then in that liter of seawater, there are going to be more than 10 billion bacteria and a hundred billion viruses. Now, I don't know if those numbers wrong. That is a hundred billion different viruses. And you might be thinking to yourself, well, that is an astronomical number. But scientists also estimate that the number of viruses on earth is more than 10 billion times the number of stars in the universe.
But the next sentence is the key sentence I want you to take away from today's live stream. Only about one in a billion microbes is a human pathogen. Focus on that. One in a billion microbes. So out of all of the different types of microbes that could potentially cause disease, about 1400 are known to cause disease in humans. And we need to be aware of this, because not all the different bugs out there are dangerous to us. So although pathogens can be dangerous, it is important to understand what makes them cause disease. And so what are some of the classic diseases? Well, obviously for 2020, SARS-CoV-2 causes the COVID-19 disease. It is the virus that causes the disease.
But let's jump into some history as well. And I have to go back to say the Justinian plague in 540 or 541, for example, a hundred million Europeans died. And in fact, this was the cause of the Roman Empire falling. And this was caused by a particular bacterium (Yersinia pestis) that grows in the gut microbiome of fleas. And those fleas grow on rodents, and then those rodents pass the disease on. Think of it. The fall of the Roman Empire was due to a microbiological threat.
And many of you have probably also heard of the Black death. The Black death was also caused by this particular flea-borne bacterium (Yersinia pestis). And it's quite incredible to think that one-third of Europe's population was killed due to the spread of this bacterium through infected fleas and infected rodents.
Now, typical other examples that most people are aware of, of bacterial threats to humankind. Well, obviously anthrax is one well-known term or name that has been linked to biowarfare. But originally this micro-organism, Bacillus anthracis, causes disease in animals. And this can then, unfortunately it has been exploited in warfare, but originally is a serious threat in cattle. Similarly, botulinum. Botulinum toxin has been exploited in the cosmetic industry because pathogens cause disease by producing toxins. And these are, in many cases, quite poisonous. And this botulinum is found in the microorganism called Clostridium botulinum, which occurs when canned goods are improperly canned. And it's a microorganism that doesn't like air and oxygen. So it grows in an anaerobic environment. But you need to be aware that when live microbes colonize a host, they produce toxins and often these are waste products of the microbial cell life cycle.
So what are we going to do? Well obviously, we need to practice, as I said at the start of this live stream, good hand hygiene, good infection control practices. This is the only way that we can limit our exposure and the impact of these illnesses and diseases. Because although they are rare, there are so many microorganisms on the planet. And in fact, in a typical human body, we make up potentially 30 trillion cells. That's 12 zeros. And if you think that a million's got six zeros, 30 trillion, that's a lot of different cells. But in our gut microbiome, there's another 30 trillion microorganisms living there. So essentially our bodies are a constellation of cells and organs with microbes also growing on and in us. And we can't escape that fact and nor do we want to, but we need to be aware that only about 1400 microorganisms are pathogens.
Now, if we look at some of the key takeaways and issues that I want to talk about. Obviously this year in 2020, we can't go past the impact of coronavirus. But remember that there have been three major coronavirus pandemics, and this is the third one. Similarly, influenza, right at the start of the coronavirus pandemic, at the start of 2020, many people were saying, "It's not that serious, or it won't be that serious. After all, we have influenza every year." But we need to appreciate that influenza is also constantly mutating and it's changing the proteins on the surface of the virus. And that then impacts how our immune system responds to that particular influenza.
And we can't go past the fact that there are new emerging yeast-like fungal threats, like Candida auris, which was only discovered and became a problem around about 2009. And that is causing severe problems in hospitals and also in aged care settings. So we really need to be aware of this issue.
But where are we going to go from here? Because the whole point about infection control is to control the risks. And so I want to summarize the key ways to prevent infectious disease. And obviously, number one is to practice good hand hygiene and cough etiquette, because we want to limit the spread of respiratory pathogens and where they end up being deposited on surfaces, leading into the next major way of preventing infectious disease, which is to implement routine, environmental cleaning, and disinfection.
Now, we need to, from time to time, take advantage of PPE and use masks and gloves when necessary. And this could be particularly important when handling blood or even sewage or anything like that. Last week, we were talking about Category 3, or black water events, affecting residential and commercial properties through unexpected storms. That's when you need to take proactive infection control steps.
As well, we need to be aware of the value of exclusions and cohorting of sick people or potentially infectious people. Certainly with the lockdowns that have occurred in various parts of the world, the point of that is to reduce the spread or reduce the time in which an infection spreads through a population.
And this concept of cleaning needs to be incorporated within our daily lives, meaning that infection control principles and practices need to be discussed and planned for. And that is the whole point of education within society and taking advantage of what we have learned through history to minimize the impact of these illnesses on your and my health.
In any case, I look forward to talking to you next week. Have a great week, stay safe and bye for now.
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Janik, E.; Ceremuga, M.; Niemcewicz, M.; Bijak, M. Dangerous Pathogens as a Potential Problem for Public Health. Medicina 2020, 56, 591. https://doi.org/10.3390/medicina56110591
Candida auris: A Drug-resistant Germ That Spreads in Healthcare Facilities | Candida auris | Fungal Diseases | CDC. (2020). Retrieved 16 November 2020, from https://www.cdc.gov/fungal/candida-auris/c-auris-drug-resistant.html
Department of Health | Chapter 8: Infection control. (2020). Retrieved 16 November 2020, from https://www1.health.gov.au/internet/publications/publishing.nsf/Content/cda-cdna-norovirus.htm-l~cda-cdna-norovirus.htm-l-8
When Anthrax-Laced Letters Terrorized the Nation. (2020). Retrieved 16 November 2020, from https://www.history.com/news/anthrax-attacks-terrorism-letters