“Disease X” threatens our world

Increasingly our attention is being directed to the possibility of the world experiencing another global pandemic possibly much more severe than any we have ever experienced before. Recently the WHO issued a formal warning that some hypothetical "Disease X" could potentially wipe out millions of humans.

"Disease X" identifies not a specific known disease but is rather a WHO construct representing some currently unknown infectious disease that could emerge at any time and cause millions of deaths. According to the WHO, "Disease X" stands for the unknown pathogen underlying a potential world pandemic against which we currently have no defence.

Interestingly enough the WHO announcement of "Disease X" appeared on the 100 year anniversary of the first cases of Spanish Flu that appeared at Fort Riley, Kansas in 1918.

There is little doubt that our world still struggles to fully understand and control a large number of infectious diseases including Ebola, Marburg virus, Lassa Fever, MERS, Zika and Crimean-Congo haemorrhagic fever, Dengue and numerous others.

To this list the WHO has now added "Disease X" in recognition of another deadly pathogen expected to soon emerge and produce a pandemic unlike anything that we have previously seen. In the course of their announcement the WHO also noted that for many of the diseases in their list, as well as many others, there exist few effective drugs or vaccines and that many of the listed diseases could cause a major public health emergency.

From another perspective it is also possible that "Disease X" could be the outcome of a bioterrorist exercise or perhaps even the deliberate dispersal of a state sponsored nerve agent.

The biggest thing about pandemics is that we tend to always be surprised by their appearance. They highlight how little we have learned from our previous encounters with infectious disease outbreaks and how limited are the weapons we can bring to bear in our attempts to control and limit such disasters.

In addition, we continually fail to appreciate the links between the animal world and our health. Of the 400 or so infections that have captured our attention over the last 80 odd years, more than 70% have been zoonotic or animal diseases.

The bacterial and viral world associated with wild and domesticated animals is vast with animal and human contact becoming much greater as our world develops with expanding trade and travel making such contact more likely.

But how safe are we?

Only a month ago a new strain of avian flu (H7N4) emerged in China and infected humans for the first time. The virus jumped from poultry to infect a 68 year old Chinese woman in Eastern China who was hospitalised with severe respiratory symptoms.

H7N9 is now widespread among Chinese poultry but has yet to develop the ability to easily spread to humans. However, there seems little doubt that a large amount of viral evolution is taking place in our world particularly in livestock, birds and wild animals.