WHO Adds 'Disease X' to List of Potential Pandemic Killers

Marcia Frellick

March 12, 2018

At the end of this year's World Health Organization (WHO) list of pathogens that could cause a worldwide pandemic is a mysterious addition: "Disease X."

"Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease," the WHO explains on its website.

The purpose of listing it is to inspire crosscutting research and development (R&D) efforts for well-known diseases that would be relevant for an as-yet-unknown disease, the WHO states. Possible sources of such a disease include a mutation of a known disease, a disease arising through a human-animal interaction, or an act of terror.

Each year, the WHO identifies diseases for which there are no or insufficient countermeasures and that pose a public health risk because of their potential for causing an epidemic. Those diseases become the focus of the work of the R& D blueprint.

One of the scientists advising the WHO committee, John-Arne Rottingen, MD, PhD, of Norway, told the Telegraph,"History tells us that it is likely the next big outbreak will be something we have not seen before. 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."

The blueprint seeks to improve coordination, funding, and communication; accelerate R&D; and develop a response plan that shortens the time from outbreak to the time that vaccines are available for treatment.

The Full List

The other diseases and pathogens prioritized in this year's blueprint are (alphabetically) Crimean-Congo hemorrhagic fever; Ebola and Marburg viruses; Lassa fever; Middle East respiratory syndrome (MERS) coronavirus and severe acute respiratory syndrome (SARS); Nipah and henipavirus diseases; Rift Valley fever; and Zika.

The list is developed by a global team of experts in scientific, medical, and regulatory roles. The roadmaps for each disease will be published for wide dissemination.

Also at this year's blueprint meeting, which was held in February in Geneva, Switzerland, a number of other diseases were considered for the list. According to a WHO statement, they included Arenaviral hemorrhagic fevers other than Lassa fever; Chikungunya; highly pathogenic coronaviral diseases other than MERS and SARS; emergent nonpolio enteroviruses, including EV71 and D68; and severe fever with thrombocytopenia syndrome (SFTS).

"They should be watched carefully and considered again at the next annual review," the WHO said.

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