The World Health Organisation (WHO) has added a mysterious affliction — dubbed ‘Disease X’ — to the list of diseases they fear could start a global pandemic in the future.

Image credits: Bruno Glätsch.

Each year, the Geneva-based WHO — tasked with monitoring and safeguarding world health — convenes a high-level meeting of senior scientists, listing diseases that risk prompting a major international public health emergency. Contenders are weighed primarily on their potential to rapidly epidemics of huge proportions, even global pandemics, as well as the real-life damage they have proven capable of.

In previous years, the listing was made up of viruses that had seen outbreaks in recent years, such as Ebola, Zika, Lassa fever, or Sars (severe acute respiratory syndrome). But for the first time the WHO introduces a mysterious condition on the list, dubbed “Disease X“.

Eyes on the horizon

Despite its name, disease X is not spread around by one group of highly-gifted mutant children in both comic and film. In fact, it’s not actually ‘real’ in the strict sense of the word — Disease X is a hypothetical virus. It’s something that could emerge and then go on to cause widespread infection across the globe.

Luckily, for now, it all hinges on that ‘could’. Disease X is a placeholder: a reminder not to get complacent in our fight against would-be pathogens.

“Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease”, the WHO said in a statement.

The statement went on to explain that adding it to the list should help promote and guide “research and development preparedness that is relevant for an unknown Disease X as far as possible.” The mysterious nature of the disease is meant to ensure flexible planning of diagnostics tests and vaccine strategies, so that that they may be applied to a wide range of possible scenarios.

“History tells us that it is likely the next big outbreak will be something we have not seen before”, John-Arne Rottingen, chief executive of the Research Council of Norway and a scientific adviser to the WHO committee, said for The Telegraph.

“We want to see ‘plug and play’ platforms developed which will work for any, or a wide number of diseases; systems that will allow us to create countermeasures at speed.”

Disease X could spring up from a lot of different sources and infect us via innumerable vectors, Mr. Rottingen says, although zoonotic transmission (an animal virus evolving to infect humans) is the most likely. Ebola, salmonella, and HIV are believed to be zoonoses.

In modern times, humans have spread across the face of the planet, inhabiting and shaping virtually all ecosystems. This has also brought us in closer contact and closer contact with more species of animals than ever before, exponentially increasing the likelihood of zoonoses.

“It’s a natural process and it is vital that we are aware and prepare. It is probably the greatest risk,” Mr. Rotingen adds.

Given the rapid development of gene-editing technologies, Disease X could also spring up from human error or malevolence — in which case, having a flexible, widely-applicable plan of action is of paramount importance. Last week’s events showed just how far the reticence of governmental or private actors on using chemical and bio-weapons has decayed, further fanning concerns that Disease X might come from a human laboratory.

Whatever the case may be, the WHO hopes its list will spur governments across the globe to invest more into strengthening local health systems. Primary care systems (local doctors and nurses) are key to safeguarding public health, as they’re our best bet for detecting outbreaks of a new disease early on, and containing it before it spreads.

The WHO says it omitted several groups of diseases, such as hemorrhagic fevers and emergent non-polio enteroviruses from its priority list. However, it also warned that these pathogens still pose a serious risk to public health, and should be “watched carefully”. These classes will be considered for inclusion on next year’s list.