An ever-present danger

In spring 2009, there was an outbreak in Mexico of an influenza pandemic that spread unstoppably around the world in just a few weeks. Many people were taken by surprise as they hadn’t imagined that, with all the advances in medicine today, we could still feel so helpless when faced with such a common virus. Yet, scientists had been predicting it for quite some time. When the first edition of this book was published, over a decade ago, by which time that pandemic had started to abate, I was interviewed by some newspapers and repeated the same thing several times: it was indisputable that there would be another pandemic in a few years’ time, and we had better prepare in case the virus that would be circulating then turned out to be more aggressive than A(H1N1), the so-called ‘swine flu’ virus, which was creating so many problems. Such long-term prophecies are easy to make because, if you are wrong, no one remembers, so you don’t get taken to task about it afterwards. But, in this case, it wasn’t prediction but certainty. All the experts I had spoken to or read while writing this book agreed that it was inevitable. Everyone who had sufficiently studied the matter came to the same conclusion: it wasn’t a matter of waiting to see if it would happen but when it would happen.

When I said this, people looked at me not so much with fear as with an amused or incredulous expression. Another alarmist, they must have thought. In the Epilogue of this book, I explain how the publishers of the first version were also surprised when I anticipated the 2009 pandemic some months before it happened. They had an excuse, because they hadn’t experienced an infectious disease of such dimensions, but the attitude should have changed after the A(H1N1) flu, which could be regarded as the first pandemic of the modern era, the first to have attacked a globalized, frontierless world. This should have warned us of what can happen when, faced with the appearance of an unknown virus against which we have no defences, we are obliged to act swiftly in order to avert a possible tragedy. But, even so, the outbreak of COVID-19, the disease caused by the new virus called SARS-CoV-2, caught us unawares.

The responses to this second great twenty-first century world health crisis (in terms of viruses) are very similar to those of the first one, namely confusion, panic and uncertainty. Once again, mismanaged information has sown distrust among the public. Perhaps there is one slight improvement in that many countries have responded faster and have shared important data more efficiently. Despite the doubts and unnecessary delays of the early weeks, protective measures are now being more firmly applied. Yet, there are many issues still to be resolved if we want to be better prepared for future pandemics.

Fortunately, SARS-CoV-2 isn’t the ‘supervirus’ that I talk about later in these pages, but it does raise more logistical problems than any of the flu viruses we’ve seen recently. Although we are still not well enough informed about it, we do know that it spreads very fast (partly because those affected are contagious for a long period without symptoms), and that it has a relatively low mortality rate of probably somewhere near 1 per cent. To give some perspective, this is ten times higher than the 0.1 per cent for seasonal flu but much lower than the 50–80 per cent for Ebola. If we add up these factors, as well as the many uncertainties, there are more than enough reasons to be cautious and to act as fast as possible. It’s true that the symptoms it presents are relatively mild in most cases, but in some, especially for certain groups of the population (for example, elderly people and those with serious illnesses), it can be fatal. This, together with the great ease of contagion, can create very serious problems of global health, which is why it is essential to prevent its spread as soon as possible.

However, although COVID-19 is taking up so much media space, it isn’t the only infectious disease we should be worried about. In terms of health impact, the four big epidemics and pandemics are still influenza, AIDS, malaria and tuberculosis. It’s true that we’ve recently had the biggest Ebola outbreak in history, but it’s still a disease that is restricted to certain areas of the globe. At the same time, we’ve seen how the coronavirus family has gained prominence, and how these microbes are capable of creating worldwide alerts. The first serious illness caused by these viruses was SARS which, though it was seen as a possible long-term risk at the beginning of the century, appears to be fairly well under control for the moment. After SARS, in 2012 there was MERS (Middle East Respiratory Syndrome), but this, too, remained quite localized. It wasn’t until the appearance of the third great coronavirus, SARS-CoV-2, that all the alarms went off.

So, are the coronaviruses the latest danger for humanity? Would they deserve a chapter alongside the other four major infectious diseases? Right now, it’s hard to know. Coronaviruses usually come from bats, which act as reservoirs, the places where the viruses survive and reproduce. And it’s highly probable that other strains will end up jumping to humans in areas where there’s more contact with animals (and China is one of the main loci of the problem because of its traditions and lax regulation of public markets where wild animals are sold). But we will need to wait and see whether or not this ends up becoming a major health problem in the coming decades.

As for COVID-19, its impact will depend on how quickly an effective vaccine is found, produced and administered, and on the virus’s ability to keep changing. It seems clear that it’s a big enough threat to be taken seriously, and that it’s going to cause major problems for quite some time. But, the most likely thing is that we will end up getting the better of it, if all goes well. It’s possible that, afterwards, there will still be outbreaks but, in normal circumstances – once a good part of the population has a certain immunity after coming into contact with the virus, and when we have the appropriate complementary tools (vaccine, antivirals, and so on) – it would never cause another pandemic like that of 2020. Nevertheless, this doesn’t mean that we can lower our guard. I must insist that there will be more pandemics, and the danger that one of them will be caused by an even more aggressive virus is always going to be present.

Let’s do our homework

Meanwhile, what can we do? Prepare ourselves for the future. It’s easy to forget the latent problem of pandemics when we’ve just overcome one and, in statistical terms, it’s not very likely that the next one will appear any time soon. But governments have the obligation to plan rapid response measures and, even more important, to instruct the population. Unless people – all the people – participate, we won’t be able to confront infections with any guarantee of success. We’ve already seen this twice in the twenty-first century: when there’s a crisis at the global level, it’s necessary to count on everyone to root out the problem. The conclusions we can draw in 2020 are the same as those reached in 2009. Most importantly: when a new virus appears, rapid, coordinated action is necessary until we understand the extent of the symptoms it’s causing, even if they seem mild at first. And we can only achieve this if we all understand how an infectious disease works and what the real power of microbes is.

Though it may seem excessive, isolating infected populations, encouraging hygiene and avoiding large gatherings of people are highly effective strategies in these situations, especially when it comes to making sure that the disease doesn’t cause its own particular kind of collapse of a country’s health system, which would end up with many collateral victims. This is crucial in the early phases of an epidemic. But it’s also necessary to improve public management of the crisis, which is invariably one of the weak points. And there will always be someone who believes the whole thing is a plot or an exaggeration, but we must manage to ensure that this position remains marginal, and that people listen to those who know what they are talking about. Hence, there needs to be a sound, well-coordinated communication strategy and, if possible, one with a single, reliable source of information (maybe the WHO, or maybe a new body) backed by all the authorities and the media and making the details widely available. And all of us also need to make an effort to learn a bit more about microbes.

SARS and MERS have been warnings of the danger that a microbe from this family could represent in the right conditions, and scientists spoke out loud and clear to announce it. Many people thought they were exaggerating because neither of the two epidemics turned out to be as serious as originally predicted. Now, with millions affected by COVID-19, from Asia to America and everywhere in-between, the fear of being vulnerable to the microbes around us has become generalized. Which position is more correct? Shrugging it off to the point of ignoring the experts’ warnings, or panicking about going outside and breathing air that’s full of invisible killers? The best idea, of course, is to find a middle course.

However, in order to make these kinds of decisions, we need clear information about the present risks of suffering from a serious infection and what we can do to prevent it. It isn’t always easy to obtain this because we are constantly finding clashing opinions in the media, ranging from those announcing an apocalypse to others who believe there is nothing to worry about. Who is right? We must respect viruses and bacteria and understand that we can’t always defeat them, and now, well into the twenty-first century, we also need to know the extent to which it’s possible that a pandemic can cause millions of deaths, as has happened several times throughout history.

A tool for understanding the present and preparing for the future

This is where we scientists can help a little. Popular science books like this can make a humble contribution to general knowledge and, in doing so, gradually ensure that microbes cease to be the great unknowns we only talk about when it’s already too late. Here, you will find some tools offering a better understanding of how infections work and what resources we have for stopping them. This information could be useful in the future, but it has special relevance now when COVID-19 has caused such an upheaval to our way of life. That is the reasoning behind publication of this updated, expanded edition, which includes everything we know so far about coronaviruses.

In the following pages, I’ve tried to fill in the gaps in general knowledge about microbes and to provide readers with a direct account of, and basic data about, such common but, in fact, little understood diseases like flu and AIDS, which are caused by the most important microbes. On some fronts of our struggle against infections, we remain in a tactical draw, with no guarantees that the situation will continue like this indefinitely. On others, we are clearly losing the game. And according to some experts, the situation can get worse at any time and we won’t be able to do anything to prevent it. We shouldn’t even count on our few victories because all the ground we’ve gained could be lost overnight if we are not careful.

Few fields arouse as much fear and incomprehension as microbiology, the study of invisible organisms that are as likely to help us to survive as to wipe us off the face of the Earth. In recent years, we’ve not only seen the spectre of influenza making front-page news; we’ve also learned to live with AIDS – the most significant pandemic our species has suffered for centuries – and to such an extent that many people have lost respect for it. We’ve heard news of the advance of a type of tuberculosis that can’t be cured with any drug, but we think that this is a problem that will never affect us. Thanks to irresponsible media campaigns, we’ve become so scared of vaccines that child health has regressed by several decades. We’ve discovered that a small amount of white powder inside an envelope can keep a whole country terrified for months. We’ve feared that the next war could be fought by throwing deadly bacteria at civilian populations. We’ve seen how the military considered that a disease we believed was eradicated could be more effective than an atomic bomb. And lurking behind all this are always the same culprits: microbes.

We must realize that viruses and bacteria haven’t only shaped the history of humanity, they are also responsible for millions of deaths, although they are not always front-page news. We need to know the subject well enough not to be flummoxed by the inflated reports we find in the media but, at the same time, to know when we have to act quickly. We must be aware of the strategies we have within our reach for combating microorganisms and the extent to which they can protect us. And, above all, we need to put an end to a series of myths and false beliefs that are hindering advances in the area of health. My aim as an educator is to remedy some of these shortcomings.

The book is divided into two parts, which are independent and can be read in the order the reader prefers. In the first, more general part, I will give an account of what microorganisms are and describe some of the historic pandemics that have seriously threatened our survival. The second part focuses on the main infectious diseases we haven’t yet managed to control; namely, what we can rightly call the four great modern plagues: influenza, AIDS, tuberculosis and malaria. They are important because of the number of people they affect around the world, their serious economic and social impact, their aggressiveness and, in some cases, the scant means we still have for fighting them. Some have already spread all over the planet. Others are circumscribed to certain areas, but that doesn’t mean they don’t cause large numbers of casualties. I will assess how far we are from defeating them and the risks of seeing them turning into tragedies beyond our control. I will also discuss, in particular, the gravity of the present pandemic and how it’s expected to evolve.

In this book, I want to raise several questions that I believe are necessary. Does our future depend on microorganisms? Why do antibiotics stop being effective? How much longer will they serve us? Will an AIDS vaccine ever be found? Or a cure? Why are we so afraid of influenza coming from animals, like bird or swine flu? Could a flu epidemic today wipe out half the world’s population? Do we have the means to stop dangerous infections before they spread? Should we fear an attack with biological weapons? Are we immune to infectious diseases that have been eradicated? What can we do to avoid being infected? Can vaccines cause autism? We will now move on to delve into the fascinating world of viruses and bacteria in order to find the answers.

I don’t think anyone would doubt today that infectious diseases are a global problem. They start in one corner of the planet, but our lifestyle helps them to spread like wildfire. Pandemics are still frequent, and we must learn from every episode so we can do better next time. These are problems we can’t ignore. I hope this book will help readers to see what it means to share the planet with all these invisible enemies and that, at the end of the day, we will be able to find together that much-needed point between alarm and caution which will allow us to survive as a species for many more millennia.