What you need to know about plagues, pandemics and planetary health

You’ve probably heard the word ‘pandemic’ countless times in the last couple of years – and maybe wondered: what does it mean? Have we ever experienced one before? How do infectious diseases start and how do they move around the world? Who identifies them and how are they stopped?

In 2018, I wrote George and the Ship of Time, a fantasy adventure story set in the future. I worked with a huge range of scientists and experts to create a series of essays about their research for the book and asked them to describe what might happen in the future.

One of those essays is by the simply brilliant Dr Mary Dobson, a historian of infectious diseases at Cambridge University – and now it’s more relevant than ever. It’s called ‘Plagues, pandemics and planetary health.’ It’s packed with information and facts, it’s a great read and also, it isn’t scary! Because this essay was written in 2018, it doesn’t include information about the coronavirus but it’s a great way to begin to understand infectious diseases, based on real information.

Our microscopic world

The word ‘plague’ is generally associated with its two main forms – bubonic and pneumonic plague – and outbreaks of both can still occur. When infectious diseases like the plague are widespread, as with the Black Death, they are often described as ‘epidemics’ or ‘pandemics’. Infectious diseases are caused by crafty microscopic undercover agents (micro-organisms), which typically take the form of bacteria, viruses or parasites. Not all micro-organisms are dangerous to humans but, when they are, they can be called ‘pathogens’.

Airborne pathogens can be spread from person to person – for example, by coughing or sneezing. But pathogens can also be water or food-borne, or they can be spread by infected animals and biting insects. There are theories that some disease-causing micro-organisms might originally have come from outer space! 

Since the late 19th century, generations of brilliant scientists have discovered the causes and chains of transmission of many infectious diseases, and it is through this understanding that we can come up with effective solutions to prevent them from spreading across our ever-increasingly interconnected globe.

The influenza pandemic of 1918-19

The so-called ‘Spanish flu’ killed between 50 and 100 million people across the world. There was, at that time, no cure, no vaccine and no understanding of the ‘invisible’ virus responsible. But people soon learned that influenza was a highly contagious disease and that ‘coughs and sneezes spread diseases’. A renewed interest in this historic pandemic (and why this strain of flu was so lethal) has been sparked by the recent scares of avian or ‘bird’ flu and the 2009 ‘swine’ flu pandemic.

The SARS pandemic of 2003

The speed of air travel around the globe has enabled the ever more rapid spread of pandemic diseases. Take, for example, the first major, and previously unknown, pandemic of the 21st century – SARS (severe acute respiratory syndrome). In 2003 SARS ‘jetted’ from China to Hong Kong to Canada, and on to almost every continent, before eventually being contained through public health action coordinated by the World Health Organization (WHO). Luckily, scientists across the world were able to track the progression of the disease, share their findings via the internet, and rapidly identify its cause – a virus intriguingly related to the common cold but far more deadly.

Headline news: Ebola and Zika virus

Scientists have in fact found that many infectious diseases start in rodents, animals such as monkeys and chimpanzees, birds, and even bats, and then ‘jump’ into humans. SARS may well have originated in bats. Ebola, too, probably existed as a virus in bats before emerging as a human disease in the mid-1990s. Shocking scenes of the 2014–15 Ebola epidemic in West Africa were shown by the media, as were the incredible efforts of local and international teams to stop the outbreak. With no vaccine or cure available, thousands of lives were saved by determined healthcare workers who wore protective gear (rather like spacesuits) and tended those affected. Eventually, this frightening and lethal disease was brought to a halt, but scientists are now constantly on the lookout to detect any future outbreaks quickly while they continue to search for a vaccine or cure.

Attention has also been focused on diseases transmitted by the bite of infected mosquitoes. Zika virus was first identified in the 1940s in the Zika Forest in Africa but it was only more recently, when major outbreaks occurred in a number of countries across the globe, that serious concern was raised about its potential risks. As with Ebola, there is yet no known cure: taking sensible precautions – in particular avoiding certain regions and protecting against mosquito bites, is so far the only way to avoid getting Zika virus.

Let’s not forget the old and neglected tropical diseases

There are many severe and, indeed, ancient diseases of the sub-tropical and tropical world. In parts of Africa, in spite of optimistic progress in recent decades, every minute or so a child dies of yet another mosquito-borne disease: malaria. Other, less well-known, diseases are now called ‘neglected tropical diseases’. Some are spread by insects, some by contaminated water, and some are linked to parasitic worms that live inside the human body. Unlike pandemics that threaten the whole world, these diseases are not often headline news but nevertheless deserve attention as they affect the most vulnerable people on the planet who often have limited access to modern medicines and healthcare.

Success stories!

The remarkable eradication of smallpox

But let’s look on the bright side. Thanks to medical science, tremendous progress has been made to identify and combat infectious deadly diseases. Two great success stories are the development of vaccines and life-saving antibiotics. A truly remarkable story is the global eradication of smallpox – one of the most feared of all infectious diseases in the past. There was never a cure for smallpox, but with the introduction of a vaccine, the disease was finally wiped off the face of the Earth by 1980. There is every hope now that another virus – polio – will, through a vaccination programme, be the next major human disease to become history.

Our future: what can you do?

Scientists working in the field of newly emerging infectious diseases are like detectives. Nobody knows when the next epidemic or pandemic will strike, but being prepared and acting fast is vital. In the future, there are fantastic opportunities for you to play a major and ground-breaking role by becoming skilled in human or veterinary medicine, science, nursing, and related fields of healthcare research and practice. The world desperately needs those who have the brains, passion and persistence to come up with new cures, vaccines, diagnostic tests and bright ideas about how to prevent future pandemic threats, or tackle older and neglected diseases of the world’s poorest populations. In short, to become champions for planetary health.