Disease X: The term is very misleading

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It has been nearly more than 5 months since I last wrote a blog piece here all thanks to a busy schedule. There have been too many things that I wish I would have written about. Anyways, thanks to all those readers who enquired if I would still be writing or I have quit. Nope I havent quit. I just took a Mega break.

The latest sensation in the field of infectious disease is something called as "Disease X". This fancy and scary term is talked about in virtually every leading news outlet. After witnessing some of the most discussed Global emergencies such as SARS, MERS and Ebola Disease X is being projected as the next deadly pandemic in the making. So what exactly is Disease X? In its most essential sense, Disease X is a hypothetical infectious agent that is expected to cause a devastating outbreak at a global scale.

According to the WHO, "Represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease". Dr. Anthony Fauci, further clarfies, "As experience has taught us more often than not the thing that is gonna hit us is something that we did not anticipate. Just the way we didn't anticipate Zika, we didn't think there would be an Ebola that would hit cities." Source

Photo 1: Disease X.

In May 2015, the WHO was requested to come up with a plan for identifing potential pathogens of pandemic capabilities and how it could be handled and tackled. The first list tentative list was published on 10th Decembe 2015 based on expert opinions and understanding. This document formed the basis for "List of Blueprint priority diseases". The orignial list of disease priorities included Crimean Congo haemorrhagic fever, Ebola virus disease and Marburg, Lassa fever, MERS and SARS coronavirus diseases, Nipah and Rift Valley fever.

In February 2015, WHO published a objective methodology called as "Methodology for Prioritizing Severe Emerging Diseases for Research and Development", which is aimed at determining what agents should be classified as priority. This is mainly based on factors such as research and understanding already available, pandemic potential, immunity etc. Based on the assessment, a second revision of List of Blueprint priority diseases was released. The agents include

• Crimean-Congo haemorrhagic fever (CCHF)
• Ebola virus disease and Marburg virus disease
• Lassa fever
• Middle East respiratory syndrome coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS)
• Nipah and henipaviral diseases
• Rift Valley fever (RVF)
• Zika
• Disease X

It should be noted that this list is not absolute and is more of a guideline representing where research has to be prioritsed for epidemic/pandemic preparedness. Disease X is an unknown entity. This could be anything that we havent identified yet to cause devastating infection.

Disease X is thus a term given to known unknow that could potentially cause significant problem. In other words, "We have no idea whats on the next in the list". Take into consideration, WHO committee science adviser John-Arne Rottingen says, “It may seem strange to be adding an ‘X,’ but the point is to make sure we prepare and plan flexibly in terms of vaccines and diagnostic tests. 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.”