Preparing For Disease X Could Reduce The Likelihood Of Future Pandemics


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

The WHO are searching for Disease X. SimpleB/Shutterstock

The WHO are searching for Disease X. SimpleB/

When a novel disease that can infect humans arises, there is always a “Patient Zero”. For clinicians investigating patients who present with an unusual set of symptoms, it raises the question: could this be “Disease X”?

What is disease x?

According to the World Health Organization (WHO), Disease X is a placeholder name used to represent “the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease.” The idea of naming an as of yet fictitious disease is to increase our preparedness for the next pandemic by researching what’s out there and developing treatments to tackle groups of diseases.



This year, the news and our lives have been dominated by the COVID-19 pandemic which is now the biggest cause of death in the United States, killing more people than cancer or heart disease. When it became known to science, it joined SARS and MERS as another coronavirus for which humankind had never developed a vaccine. Following months of research, development and global collaboration, there are now several vaccines available to prevent COVID-19 or prevent its worst and most fatal symptoms. However, in the time it took to create the vaccine the world had lost over a million people to the disease. The concept of Disease X is to shorten this fatal period by ensuring that the way we live and the medicines we have ready lessen the chances of another deadly disease sweeping the globe.

Outbreaks of Avian Flu have been detected in chicken farms across the globe. David Tadevosian/

where could disease x come from? 

Zoonotic diseases (illnesses which pass from animals to humans) have been responsible for some of the worst epidemics and pandemics in human history. What’s worse is that the way parts of the globe function in society is making it easier for these diseases to find their way into a human host. Habitat degradation is one of the leading causes as when we destroy land inhabited by animals, we force them to relocate, many of which end up living alongside humans.


Rats, bats and insects have all been responsible for passing diseases onto humans, and some of these animals (particularly bats) act as disease reservoirs. This term summarizes any person, animal, plant, soil or substance which is naturally a host for an infectious agent which multiplies within it without causing any significant symptoms for the carrier. These animals become a significant source of disease, passing the illness on to other living things which don’t fare so well when infected.

what diseases do humans catch from animals?

Yellow fever, influenza, rabies and Lyme disease are all examples of disease which has passed from animals to humans, sometimes reaching us via an intermediate host. One theory for the origin of COVID-19 is that it passed from bats to an intermediary host and pangolins, tree shrews and civets have all been the subject of investigations into the source of the disease. At time of writing, we still don’t know which species first passed the coronavirus to humans and it’s possible we may never find out.

Insufficient stocks of personal protective equipments results in the deaths of medical staff across the world during the COVID-19 pandemic. David Herraez Caldaza/

What can we do to prevent pandemics? 

One certainty remains, however, which is that if societies continue to function as they have done in the past, we are putting ourselves at a real and demonstrable risk of more pandemics and a higher death count. Countries such as the United Kingdom suffered greatly when COVID-19 began to spread as insufficient personal protective equipment (PPE) and a shortage of ventilators put both patients and medical staff at risk. By targeting research and development to tackle Disease X we can prepare by ensuring hospitals are sufficiently stocked with life saving equipment.

Farming large quantities of captive animals in small spaces is one practice which allows for the mutation of viruses which could prove pivotal for humankind. Earlier this year a mutation was identified in a small number of minks which some scientists could lessen the efficacy of the vaccine if it were to spread. Fortunately, this mutation is thought to have since died out, but its existence demonstrates how a virus could turn into a dramatically different beast if left to blaze through farmed animals which come into contact with humans.

Habitat degradation and deforestation was the subject of a documentary by wildlife superstar David Attenborough this year. In the documentary, infographics demonstrated how carbon has driven dramatically within the presenters life tims the transmission of the virus, of the new pathogens.

"We are now in a world where new pathogens will come out. And that's what constitutes a threat for humanity.”


e, some of which can be attributed to the degradation of wild spaces which sequester carbon. If we fail to take his message seriously, the same degradation could prove to be the cause of a pandemic even more deadly than COVID-19. Animals need to be able to exist on Earth without coming into close contact with humans if we’re to avoid Disease X and whatever symptoms it brings. After all, it only takes one Patient Zero to launch a global pandemic.

Deforestation increases the likelihood of wild animals entering human settlements. Rich Carey/

"If you go in the forest… you will change the ecology; and insects and rats will leave this place and come to the villages,” said Professor Jean-Jacques Muyembe Tamfum, who helped discover the Ebola virus in 1976 and continues to search for new pathogens, in an interview with CNN. “So, this i